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19-1810; Rev 1; 1/02
KIT ATION EVALU ILABLE AVA
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
General Description Features
o Dual, High-Efficiency, Synchronous-Rectified Step-Down Converters o Thin, Small (1mm High) QFN Package o Step-Up Converter for Backup Battery o Main Power Adjustable from +1.25V to +5.5V Over 2A Load Current Up to 95% Efficiency o Core Power Adjustable from 1V to 5V Internal Switches Up to 1.5A Load Current Up to 91% Efficiency o Automatic Main Battery Switchover o 100% (max) Duty Cycle o Up to 1.25MHz Switching Frequency o Input Voltage Range from +2.7V to +28V o Four Low-Voltage Detectors o 170A Quiescent Current o 8A Shutdown Current o Digital Soft-Start o Independent Shutdown Inputs
MAX1774
The MAX1774 is a complete power-supply solution for PDAs and other hand-held devices. It integrates two high-efficiency step-down converters, a boost converter for backup battery regulation, and four voltage detectors in a small 32-pin QFN or 28-pin QSOP package. The MAX1774 accepts inputs from +2.7V to +28V and provides an adjustable main output from 1.25V to 5.5V at over 2A. The secondary core converter delivers an adjustable voltage from 1V to 5V and can deliver up to 1.5A. Both the main and core regulators have separate shutdown inputs. When the AC adapter power is removed, an external Pchannel MOSFET switches input to the main battery. When the main battery is low, the backup step-up converter sustains the main output voltage. When the backup battery can no longer deliver the required load, the system shuts down safely to prevent damage. Four onboard voltage detectors monitor the status of the AC adapter power, main battery, and backup battery. The MAX1774 evaluation kit is available to help reduce design time.
________________________Applications
Hand-Held Computers PDAs Internet Access Tablets POS Terminals Subnotebooks
Pin Configurations
BKUP N.C. LXC
LBO INS N.C.
Ordering Information
PART MAX1774EEI MAX1774EMJ TEMP RANGE -40C to +85C -40C to +85C PIN-PACKAGE 28 QSOP 32 7mm x 7mm QFN
TOP VIEW
GND
SHDNC
SHDNM
32
31
30
29
28
27
26
25
GND
MDRV PGNDC PGND NDRV CVL IN PDRV CVH
1 2 3 4 5 6 7 8 10 11 12 13 14 15 16
24 23 22 21
ACO INC GND FBC CSCS+ FBM N.C.
BACKUP BATTERY MAIN BATTERY AC ADAPTER
Functional Diagram
MAIN (+3.3V)
MAX1774
20 19 18 17
MAX1774
CORE (+1.8V) AC OK LOW MAIN BATTERY DEAD MAIN BATTERY
GND
GND
9
BKOFF
LXB
LXB2
REF
BIN
DBI
ACI
LBI
32 7mm x 7mm QFN
Pin Configurations continued at end of data sheet. 1
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
ABSOLUTE MAXIMUM RATINGS
IN, SHDNM, MDRV, DBI, LBI, ACI, CVH to GND .......................................................-0.3V to +30V IN to CVH, PDRV ......................................................-0.3V to +6V BIN to CS-.................................................................-0.3V to +6V LXB to GND ................................................-0.3V to (VBIN+ 0.7V) PDRV to GND..................................(VCVH - 0.3V) to (VIN + 0.3V) All Other Pins to GND...............................................-0.3V to +6V PGND to GND .......................................................-0.3V to +0.3V Continuous Power Dissipation 28-Pin QSOP (derate 10.8mW/C above +70C)........860mW 32-Pin QFN (derate 23.2mW/C above +70C) ........1860mW Operating Temperature .......................................-40C to +85C Storage Temperature.........................................-65C to +150C Temperature (soldering, 10s) ..........................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(Figure 1, VIN = VINS +12V, VINC = VCS- = VCS+ = +3.3V, VCORE = +1.8V, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Input Voltage Input Quiescent Supply Current CS- Quiescent Supply Current Core Regulator Quiescent Supply Current Backup Mode BIN Quiescent Supply Current IN Shutdown Supply Current MAIN REGULATOR Main Output Voltage Adjust Range FBM Regulation Threshold FBM Input Current Current-Limit Threshold Minimum Current-Limit Threshold Valley Current Threshold Zero Current Threshold PDRV, NDRV Gate Drive Resistance CS- to CVL Switch Resistance PDRV, NDRV Dead Time VFBM IFBM V(CS+ - CS-) = 0 to +60mV, VIN = +3.5V to +28V VFBM = +1.3V VCS+ - VCSVCS+ - VCSVCS+ - VCSVCS+ - VCSVCS- = +3.3V, IPDRV, INDRV = 50mA ICVL = 50mA 1.25 1.21 -0.1 60 5 40 0 80 15 50 5 2 4.5 50 1.25 5.5 1.29 0.1 100 25 60 15 5.5 9.5 V V A mV mV mV mV ns SYMBOL VIN IIN ICSIINC VFBM = +1.5V, VFBC = +1.5V, V SHDNM = V SHDNC = +3.3V VFBM = +1.5V, VFBC = +1.5V, V SHDNM = V SHDNC = +3.3V VFBM = +1.5V, VFBC = +1.5V, V SHDNM = V SHDNC = +3.3V VBIN = +3.3V, CS- open VFBM = +1.5V, V SHDNM = +3.3V, V BKOFF = +1.5V, SHDNC = GND SHDNM = SHDNC = GND CONDITIONS MIN 2.7 18 110 60 TYP MAX 28 40 220 105 UNITS V A A A
IBIN
60 8
105 40
A A
2
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
ELECTRICAL CHARACTERISTICS (continued)
(Figure 1, VIN = VINS = +12V, VINC = VCS- = VCS+ = +3.3V, VCORE = +1.8V, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Maximum Duty Cycle Minimum On-Time Minimum Off-Time CORE REGULATOR Input Voltage Range INC Undervoltage Lockout Core Output Voltage Adjust Range Maximum Core Load Current FBC Regulation Threshold FBC Input Current Dropout Voltage LXC Leakage Current LXC P-Channel, N-Channel OnResistance LXC P-Channel Current Limit LXC P-Channel Minimum Current LXC N-Channel Valley Current LXC N-Channel Zero-Crossing Current LXC Dead Time Max Duty Cycle Minimum On-Time Minimum Off-Time BACKUP REGULATOR Backup Battery Input Voltage LXB N-Channel On-Resistance LXB Current Limit LXB Leakage Current BIN Leakage Current BIN, CS- Switch Resistance BIN Switch Zero-Crossing Threshold LXB Maximum On-Time Zero Crossing Detector Timeout IBIN VLXB = +5.5V, VFBM = +1.3V VBIN = +5.5V, CS- = BKOFF = SHDNC = SHDNM = GND VCS- = +3.3V, BKOFF = GND, SHDNM = CVL VBIN = +2.5V, BKOFF = SHDNC = SHDNM = CVL 2.8 7.5 17 5.6 40 VBBATT VCS- = +3.3V, ILXB = 50mA 200 0.9 1.9 350 5.5 3.5 600 1 1 15 35 9.2 V mA A A mV s s 100 170 170 400 400 690 690 ICLC 1200 100 900 40 ILXC VFBC IFBC VCORE = 1.8V (Note 1) VINC = +2.5 to +5.5V, I O U T C = 0 to 200mA VFBC = +1.3V IOUTC = 400mA VINC = +5.5V, V L X C = 0 to +5.5V -10 0.25 1800 250 1400 110 50 VINC VINC rising VINC falling 2.6 2.40 2.30 1.0 1 0.97 -0.1 0.1 1.5 1.0 1.03 0.1 0.25 10 0.5 3000 400 2400 170 2.47 2.37 5.5 2.55 2.45 5.0 V V V A V A V A mA mA mA mA ns % ns ns SYMBOL CONDITIONS MIN 100 200 200 400 400 650 650 TYP MAX UNITS % ns ns
MAX1774
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3
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
ELECTRICAL CHARACTERISTICS (continued)
(Figure 1, VIN = VINS = +12V, VINC = VCS- = VCS+ = +3.3V, VCORE = +1.8V, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER REFERENCE Reference Voltage Reference Load Regulation Reference Line Regulation Reference Sink Current CVL, CVH REGULATORS CVL Output Voltage CVL Switchover Threshold VCVL ICVL = 50mA, VCS- = 0 ICVL = 50mA, VCS- = +3.3V CS- rising, hysteresis = 100mV typical VIN = +4V, ICVH = 25mA CVH Output Voltage VCVH VIN = +12V, ICVH = 50mA CVH Switchover Threshold CVL Undervoltage Lockout LOW-VOLTAGE COMPARATORS Backup Regulator Shutdown Threshold BKOFF Input Bias Current LBI Threshold DBI Threshold BKUP Low-Input Threshold LBI, DBI Input Leakage Current LBO, BKUP, ACO, MDRV Output Low LBO, BKUP, ACO, MDRV Output Leakage Current ACI Threshold ACI Input Leakage Current INS Input Leakage Current LOGIC INPUTS SHDNM, SHDNC Input Low Voltage SHDNM, SHDNC Input High Voltage 2.0 0.4 V V VLBI = VDBI = +1.3V ISINK = 1mA VLBI = +1.3V, VACI = +12V, V ACO = V LBO = V BKUP = +5.5V, V MDRV = +28V VACI - VINS, ACI falling VACI = +1.3V VINS = +3.3V 1.5 0.22 VLBI VDBI V BKOFF V BKOFF rising V BKOFF falling V BKOFF = +5.5V VLBI falling, hysteresis = 50mV typical VDBI falling, hysteresis = 50mV typical 1.17 1.17 0.4 100 0.4 1.0 0.35 100 10 1.20 1.20 0.51 0.46 0.55 0.50 0.59 0.54 1 1.23 1.23 V A V V V nA V A V nA A VIN VIN rising, hysteresis = 350mV typ VCVL rising VCVL falling 2.40 2.30 2.40 2.6 2.8 3.2 2.47 VIN 3.4 VIN 4.2 5.5 2.47 2.37 2.55 2.45 2.55 VIN 2.8 V VIN 3.7 V V 3.1 V V VREF IREF = 0 to 50A VCS- = +2.5V to +5.5V, IREF = 50A 10 1.23 1.25 1.27 10 5 V mV mV A SYMBOL CONDITIONS MIN TYP MAX UNITS
4
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
ELECTRICAL CHARACTERISTICS (continued)
(Figure 1, VIN = VINS = +12V, VINC = VCS- = VCS+ = +3.3V, VCORE = +1.8V, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER SHDNM, SHDNC Input Low Current SHDNC Input High Current SHDNM Input High Current SYMBOL CONDITIONS SHDNM = SHDNC = GND V SHDNC = +5.5V V SHDNM = +5V 2 MIN -1 TYP MAX 1 5 25 UNITS A A A
MAX1774
ELECTRICAL CHARACTERISTICS
(Figure 1, VIN = VINS = +12V, VINC = VCS- = VCS+ = +3.3V, VCORE = +1.8V, TA = -40C to +85C, unless otherwise noted.) (Note 2)
PARAMETER Input Voltage Input Quiescent Supply Current CS- Quiescent Supply Current Core Regulator Quiescent Supply Current Backup Mode BIN Quiescent Supply Current IN Shutdown Supply Current MAIN REGULATOR Main Output Voltage Adjust Range FBM Regulation Threshold FBM Input Current Current-Limit Threshold Minimum Current-Limit Threshold Valley Current Threshold Zero Current Threshold PDRV, NDRV Gate Drive Resistance CS- to CVL Switch Resistance Maximum Duty Cycle Minimum On-Time Minimum Off-Time VFBM IFBM V(CS+ - CS-) = 0 to +60mV, VIN = +3.5V to +28V VFBM = +1.3V VCS+ - VCSVCS+ - VCSVCS+ - VCSVCS+ - VCSVCS- = +3.3V, IPDRV, INDRV = 50mA ICVL = 50mA 100 200 200 650 650 1.25 1.21 -0.1 60 5 40 0 5.5 1.29 0.1 100 25 60 15 5.5 9.5 V V A mV mV mV mV % ns ns SYMBOL VIN IIN ICSIINC VFBM = +1.5V, VFBC = +1.5V, V SHDNM = V SHDNC = +3.3V VFBM = +1.5V, VFBC = +1.5V, V SHDNM = V SHDNC = +3.3V VFBM = +1.5V, VFBC = +1.5V, V SHDNM = V SHDNC = +3.3V VBIN = +3.3V, CS- open VFBM = +1.5V, V SHDNM = +3.3V, V BKOFF = +1.5V, SHDNC = GND SHDNM = SHDNC = GND CONDITIONS MIN 2.7 MAX 28 40 220 105 UNITS V A A A
IBIN
110 40
A A
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5
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
ELECTRICAL CHARACTERISTICS (continued)
(Figure 1, VIN = VINS = +12V, VINC = VCS+ = VCS- = +3.3V, VCORE = +1.8V, TA = -40C to +85C, unless otherwise noted.) (Note 2)
PARAMETER CORE REGULATOR Input Voltage Range INC Undervoltage Lockout Core Output Voltage Adjust Range Maximum Core Load Current FBC Regulation Threshold FBC Input Current Dropout Voltage LXC Leakage Current LXC P-Channel, N-Channel On-Resistance LXC P-Channel Current Limit LXC P-Channel Minimum Current LXC N-Channel Valley Current LXC N-Channel Zero-Crossing Current Max Duty Cycle Minimum On-Time Minimum Off-Time BACKUP REGULATOR Backup Battery Input Voltage LXB N-Channel On Resistance LXB Current Limit LXB Leakage Current BIN Leakage Current BIN, CS- Switch Resistance BIN Switch Zero-Crossing Threshold LXB Maximum On-Time REFERENCE Reference Voltage Reference Load Regulation Reference Line Regulation Reference Sink Current VREF IREF = 0 to 50A VCS- = +2.5V to +5.5V, IREF = 50A 10 1.220 1.275 10 5 V mV mV A IBIN VLXB = +5.5V, VFBM = +1.3V VBIN = +5.5V, CS- = BKOFF = SHDNC = SHDNM = GND VCS- = +3.3V, BKOFF = GND, SHDNC = CVL VBIN = +2.5V, BKOFF = SHDNC = SHDNM = CVL 2.8 VBBATT VCS- = +3.3V, ILXB = 50mA 200 0.9 5.5 3.5 600 1 1 15 35 9.2 V mA A A mV s 1200 100 880 40 100 160 170 700 690 ILXC VFBC IFBC VCORE = 1.8V (Note 1) VINC = +2.5 to +5.5V, IOUTC = 0 to 200mA VFBC = +1.3V IOUTC = 400mA VINC = +5.5V, VLXC = 0 to +5.5V -10 VINC VINC rising VINC falling 2.6 2.39 2.29 1.0 1 0.97 -0.1 1.03 0.1 0.25 10 0.5 3010 420 2450 170 5.5 2.55 2.45 5.0 V V V A V A V A mA mA mA mA % ns ns SYMBOL CONDITIONS MIN MAX UNITS
6
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
ELECTRICAL CHARACTERISTICS (continued)
(Figure 1, VIN = VINS = +12V, VINC = VCS+ = VCS- = +3.3V, VCORE = +1.8V, TA = -40C to +85C, unless otherwise noted.) (Note 2)
PARAMETER CVL, CVH REGULATORS CVL Output Voltage CVL Switchover Threshold VCVL ICVL = 50mA, VCS- = 0 VCS- rising, hysteresis = 100mV typical VIN = +4V, ICVH = 25mA CVH Output Voltage VCVH VIN = +12V, ICVH = 50mA CVL Undervoltage Lockout LOW-VOLTAGE COMPARATORS Backup Regulator Shutdown Threshold BKOFF Input Bias Current LBI Threshold DBI Threshold BKUP Low-Input Threshold LBI, DBI Input Leakage Current LBO, BKUP, ACO, MDRV Output Low LBO, BKUP, ACO, MDRV Output Leakage Current ACI Threshold ACI Input Leakage Current MAIN Input Leakage Current LOGIC INPUTS SHDNM, SHDNC Input Low Voltage SHDNM, SHDNC Input High Voltage SHDNM, SHDNC Input Low Current SHDNC Input High Current SHDNM Input High Current SHDNM = SHDNC = GND V SHDNC = +5.5V V SHDNM = +28V 2.0 -1 1 5 25 VLBI, VDBI = +28V ISINK = 1mA VLBI = +1.3V, VACI = VIN = +12V, VACO = V LBO = V BKUP = +5.5V, V MDRV = +28V VACI - VINS, ACI falling VACI = +1.3V VINS = +3.3V VLBI VDBI V BKOFF V BKOFF rising V BKOFF falling V BKOFF = +5.5V VLBI falling, hysteresis = 50mV typical VDBI falling, hysteresis = 50mV typical 1.17 1.17 0.4 100 0.4 1.0 0.5 100 10 0.51 0.46 0.59 0.54 1 1.23 1.23 A V V V nA V A V nA A V VCVL rising VCVL falling 2.40 2.30 VIN - 3.65 2.57 2.47 V 2.6 2.40 3.1 2.55 VIN - 2.8 V V V SYMBOL CONDITIONS MIN MAX UNITS
MAX1774
0.4
V V A A A
Note 1: This parameter is guaranteed based on the LXC P-channel current limit and the LXC N-channel valley current. Note 2: Specifications to -40C are guaranteed by design and not production tested.
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7
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
Typical Operating Characteristics
(Circuit of Figure 1, VIN = +5V, VINC = +3.3V, TA = +25C, unless otherwise noted.)
MAIN EFFICIENCY vs. LOAD
MAX1774-01
CORE EFFICIENCY vs. LOAD
MAX1774-02
BACKUP EFFICIENCY vs. LOAD
90 80 VBBATT = +2.5V VBBATT = +1.0V
MAX1774-03
100 90 80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 1 10 100 LOAD (mA) 1000 VIN = +18V VMAIN = 3.3V VIN = +3.3V VIN = +5V
100 90 80 EFFICIENCY (%) VIN = +2.7V VIN = +3.3V VIN = +5V
100
VIN = +12V VIN = +15V
60 50 40 30 20 10 0 VCORE = 1.8V
EFFICIENCY (%)
70
70 60 50 40 30 20 10 0 VMAIN = 3.3V 0.01 0.1 1 LOAD (mA) 10 100 VBBATT = +0.8V
10,000
1
10 LOAD (mA)
100
1000
VREF ACCURACY vs. TEMPERATURE
MAX1774-04
REFERENCE LOAD REGULATION
-0.2 -0.4 VREF ACCURACY (%) -0.6 -0.8 -1.0 -1.2 -1.4 -1.6
MAX1774-05
2.0 1.5 VREF ACCURACY (%) 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 -40 -20 0 60 40 TEMPERATURE (C) 20 80
0
-1.8 -2.0 100 0 10 20 30 40 IREF (A) 50 60 70 80
MAIN SWITCHING WAVEFORMS (LIGHT LOAD 100mA)
MAX1774-06
MAIN SWITCHING WAVEFORMS (HEAVY LOAD 1A)
5V 0 40mV 20mV 0 -20mV 500mA ILI 500mA/div 0 VMAIN (AC-COUPLED) 20mV/div 20mV 0 -20mV 1500mA 1000mA IL1 500mA/div 500mA 0 5s/div VMAIN (AC-COUPLED) 20mV/div LX 5V/div
MAX1774-07
4V 0
LX 5V/div
5s/div
8
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VIN = +5V, VINC = +3.3V, TA = +25C, unless otherwise noted.)
CORE SWITCHING WAVEFORMS (LIGHT LOAD 50mA)
MAX1774-08
CORE SWITCHING WAVEFORMS (HEAVY LOAD 500mA)
MAX1774-09
4V 2V LXC 0 20mV 2V/div
3.3V 0 500mA 0
LX 2V/div
IL2 500mA/div VCORE (AC-COUPLED) 20mV/div
0 -20mV 500mA 0
VCORE (AC-COUPLED) 20mV/div L2 500mA/div
1s/div
2s/div
MAIN LINE-TRANSIENT RESPONSE
MAX1774-10
CORE LINE-TRANSIENT RESPONSE
MAX1774-11
12V 10V 5V 0 50mV
VIN 5V/div
VINC 2V 2V/div 0
4V
VMAIN (AC-COUPLED) 50mV/div
VCORE (AC-COUPLED) 50mV/div
-50mV
100s/div
1s/div
MAIN LOAD-TRANSIENT RESPONSE
MAX1774-12
MAIN LOAD-TRANSIENT RESPONSE 50mA TO 500mA
1000mA 500mA 0 IMAIN 500mA/div
MAX1774-13
500mA 0
IMAIN 500mA/div
20mV VMAIN (AC-COUPLED) -20mV 20mV/div 0 10mV 0 -10mV VMAIN (AC-COUPLED) 10mV/div
100s/div
100s/div
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9
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VIN = +5V, VINC = +3.3V, TA = +25C, unless otherwise noted.)
TURN-ON RESPONSE
5V VSHDN 5V/div 0 VMAIN VCORE
MAX1774-14
BACKUP SWITCHOVER RESPONSE
MAX1774-15
3V 2V 1V 0 400A INPUT CURRENT 200A 0
VOUT 1V/div
VBKUP 5V/div IBBATT 50mA/div VBIN 10mV/div VMAIN 10mV/div 5s/div
INPUT CURRENT 200mA/div
100s/div
Pin Description
PIN QSOP 1 2 3 QFN 30 31 32 NAME SHDNM SHDNC BKUP FUNCTION Shutdown for Main Regulator. Low voltage on SHDNM shuts off the main output. For normal operation, connect SHDNM to IN. Shutdown for Core Regulator. Low voltage on SHDNC shuts off the core output. For normal operation, connect SHDNC to CVL. Open-Drain Backup Input/Output. The device is in backup mode when BKUP is low. BKUP can be externally pulled low to place the device in backup mode. Open-Drain Drive Output. MDRV goes low when the ACI voltage drops below the main voltage plus 220mV and device is not in backup. Connect MDRV to the gate of the main battery P-channel MOSFET to switch the battery to IN when the AC adapter voltage is not present. Power Ground for the Core Converter. Connect all grounds together close to the IC. Power Ground. Ground for NDRV and core output synchronous rectifier. Connect all grounds together close to the IC. N-Channel Drive Output. Drives the main output synchronous-rectifier MOSFET. NDRV swings between CVL and PGND. Low-Side Bypass. CVL is the output of an internal LDO regulator. This is the internal power supply for the device control circuitry as well as the N-channel driver. Bypass CVL with a 1.0F or greater capacitor to GND. When CS- is above the CVL switchover threshold (2.47V), CVL is powered from the main output. Power Supply Input P-Channel Drive Output. Drives the main output high-side MOSFET switch. PDRV swings between IN and CVH. The voltage at CVH is regulated at VIN - 4.2V unless the input voltage is less than 5.5V. High-Side Drive Bypass. This is the low-side of the P-channel driver output. Bypass with a 1.0F capacitor or greater to IN. When the input voltage is less than 5.5V, CVH is switched to PGND. Backup Converter Switching Node. Connect an inductor from LXB to the backup battery and a Schottky diode to BIN to complete the backup converter. In backup mode, this step-up converter powers the main output from the backup battery through BIN.
4 5 6 7
1 2 3 4
MDRV PGNDC PGND NDRV
8
5
CVL
9 10 11
6 7 8
IN PDRV CVH
12
9
LXB
10
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
Pin Description (continued)
MAX1774
PIN QSOP -- 13 QFN 10 11 NAME LXB2 BIN FUNCTION Backup Converter Switching Node. Connect LXB2 to LXB as close to the IC as possible. Backup Battery Input. Connect BIN to the output of the backup boost regulator. Bypass BIN with a 10F or greater capacitor to GND. When the MAX1774 is in backup mode, BIN powers the main output. Backup Disable Input. Driving BKOFF below +0.5V disables the backup mode. In backup mode, the device enters shutdown when this pin is pulled low. BKOFF can be driven from a digital signal or can be used as a low battery detector to disable the backup converter when the backup battery is low. AC Adapter Low-Voltage Detect Input. Connect to adapter DC input. When the voltage at ACI falls below the voltage at INS plus +0.22V, ACO asserts. Dead Battery Input. Connect DBI to the main battery through a resistive voltage-divider. When DBI drops below +1.20V, no AC adapter is connected (ACO is low, but main output still available), BKUP asserts. Low-Battery Input. Connect LBI to the main battery through a resistive voltage-divider. When the voltage at LBI drops below +1.20V, LBO asserts. Reference Voltage Output. Bypass REF to GND with a 0.22F or greater capacitor. No Connection. Not Internally Connected. Main Output Feedback. Connect FBM to a resistive voltage-divider to set main output voltage between +1.25V to +5.5V. Main Regulator High-Side Current-Sense Input. Connect the sense resistor between CS+ and CS-. This voltage is used to set the current limit and to turn off the synchronous rectifier when the inductor current approaches zero. Main Regulator Low-Side Current-Sense Input. Connect CS- to the main output. Core Output Feedback. Connect FBC to a resistive voltage-divider to set core output between +1.0V to +5.0V. Analog Ground Core Supply Input Low AC Output. Open drain ACO asserts when ACI falls below the main output voltage plus 0.22V. Open-Drain Low-Battery Output. LBO asserts when LBI falls below +1.20V. Power-Supply Input Voltage Sense Input. Connect INS to the power-supply input voltage. Core Converter Switching Node
14
12
BKOFF
15 16 17 18 -- 19
13 14 15 16 17, 25, 29 18
ACI DBI LBI REF N.C. FBM
20 21 22 23 24 25 26 27 28
19 20 21 22 23 24 26 27 28
CS+ CSFBC GND INC ACO LBO INS LXC
Detailed Description
The MAX1774 dual step-down DC-DC converter is designed to power PDA, palmtop, and subnotebook computers. Normally, these devices require two separate power supplies-one for the processor and another higher voltage supply for the peripheral circuitry. The MAX1774 provides an adjustable +1.25V to +5.5V main output designed to power the peripheral circuitry of PDAs and similar devices. The main output delivers up to 2A output current. The lower voltage core converter has an adjustable +1.0V to +5.0V output, providing up to 1.5A output current. Both regulators utilize a proprietary regulation scheme allowing PWM operation at
medium to heavy loads, and automatically switch to pulse skipping at light loads for improved efficiency. Under low-battery conditions, the MAX1774 enters backup mode, making use of a low-voltage backup battery and a step-up regulator to power the output. Figure 1 is the MAX1774 typical application circuit.
Operating Modes for the Step-Down Converters
When delivering low output currents, the MAX1774 operates in discontinuous conduction mode. Current through the inductor starts at zero, rises as high as the minimum current limit (IMIN), then ramps down to zero during
11
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
NOTE: FOR INPUT VOLTAGES TO 28V SEE FIGURE 4 AND FIGURE 5 2.7V TO 5.5V 2.7V V IN_AC TO 5.5V MAIN BATTERY D1 NSD03A10 C5 1F NDS356AP R4 MDRV DBI R2 ACI LBI R3 1M PDRV N1 NDRV P2 FDS8928A L1 5H IN INS CVH C6 10F
P1 R1
RCS
MAIN CMAIN 47F 1.25V TO 5.5V
MAX1774
PGND
ON OFF ON OFF
SHDNM SHDNC BIN
CS+ CS-
C1 10F
D2 EP05Q 03L L3 22H
R10 LXB FBM LXB2(QFN ONLY) R11 BKOFF R5 1M ACO R6 1M C4 0.22F REF GND PGNDC BKUP INC L2 5.4H LXC R8 FBC R9 C7 1F CORE 1.0V TO CCORE 5.5V 22F LBO R7 1M
BACKUP BATTERY 0.9V TO 5.5V C2 10F
CVL C3 1F
Figure 1. Typical Application Circuit For Low-Input Voltage Applications
each cycle (see Typical Operating Characteristics). The switch waveform may exhibit ringing, which occurs at the resonant frequency of the inductor and stray capacitance, due to the residual energy trapped in the core when the rectifier MOSFET turns off. This ringing is normal and does not degrade circuit performance. When delivering medium-to-high output currents, the MAX1774 operates in PWM continuous-conduction mode. In this mode, current always flows through the inductor and never ramps to zero. The control circuit
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adjusts the switch duty cycle to maintain regulation without exceeding the peak switching current set by the current-sense resistor.
100% Duty Cycle and Dropout
The MAX1774 operates with a duty cycle up to 100%, extending the input voltage range by turning the MOSFET on continuously when the supply voltage approaches the output voltage. This services the load when conventional switching regulators with less than
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
TOFFMIN VMIN CS+ CSVVALLEY FB REF R NON VO NSW S Q TONMIN PON PON VIN PSW
VCLM
S
Q
R VZERO NONOVERLAP PROTECTION
Figure 2. Simplified Control System Block Diagram
100% duty cycle fail. Dropout voltage is defined as the difference between the input and output voltages when the input is low enough for the output to drop out of regulation. Dropout depends on the MOSFET drain-tosource on-resistance, current-sense resistor, and inductor series resistance, and is proportional to the load current: VDROPOUT = IOUT [RDS(ON) + RSENSE + RL]
Regulation Control Scheme
The MAX1774 has a unique operating scheme that allows PWM operation at medium and high current, automatically switching to pulse-skipping mode at lower currents to improve light-load efficiency. Figure 2 shows a simplified block diagram. Under medium and heavy load operation, the inductor current is continuous and the part operates in PWM mode. In this mode, depending on the duty cycle, either the minimum on-time or the minimum off-time sets the switching frequency. The duty cycle is approximately the output voltage divided by the input voltage. If the duty cycle is less than 50%, the minimum on-time controls the frequency, and the frequency is approximately f 2.5MHz D, where D is the duty cycle. If the duty cycle is greater than 50%, the minimum off-time sets the frequency, and the frequency is approximately f 2.5MHz (1 - D).
In both cases, the error comparator regulates the voltage. For low duty cycles (<50%), the P-channel MOSFET is turned on for the minimum on-time, causing fixed-on-time operation. During the MOSFET on-time, the output voltage rises. Once the MOSFET is turned off, the voltage drops to the regulation threshold, when another cycle is initiated. For high duty cycles (>50%), the MOSFET remains off for the minimum off-time, causing fixed-off-time operation. In this case, the MOSFET remains on until the output voltage rises to the regulation threshold. Then the MOSFET turns off for the minimum off-time, initiating another cycle. By switching between fixed-on-time and fixed-off-time operation, the MAX1774 can operate at high input-output ratios and still operate up to 100% duty cycle for low dropout. When operating from fixed-on-time operation, the minimum output voltage is regulated, but in fixed-off-time operation, the maximum output voltage is regulated. Thus, as the input voltage drops below approximately twice the output voltage, a decrease in line regulation can be expected. The drop in voltage is approximately VDROP VRIPPLE. At light output loads, the inductor current is discontinuous, causing the MAX1774 to operate at lower frequencies, reducing the MOSFET gate drive and switching losses. In discontinuous mode, under most circumstances, the on-time will be a fixed minimum on-time of 400ns.
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13
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
The MAX1774 features four separate current-limit threshold detectors and a watchdog timer for each of its step-down converters. In addition to the more common peak-current detector and zero-crossing detector, each converter also provides a valley-current detector, and a minimum-current detector. The valley-current detector is used to force the inductor current to drop to a lower level after hitting peak current before allowing the Pchannel MOSFET to turn on. This is a safeguard against inductor current significantly overshooting above the peak current when the inductor discharges too slowly when VOUT/L is small. The minimum-current detector ensures that a minimum current is built up in the inductor before turning off the P-channel MOSFET. This helps the inductor to charge the output near dropout when the dl/dt is small (because (VIN - VOUT) / L is small) to avoid multiple pulses and low efficiency. This feature, however, is disabled during dropout and light-load conditions where the inductor current may take too long to reach the minimum current value. A watchdog timer overrides the minimum current after the P-channel MOSFET has been on for longer than about 10s. eliminating the need for an external Schottky diode. Current sensing is internal to the device, eliminating the need for an external sense resistor. The maximum and minimum current limits are sensed through the P-channel MOSFET, while the valley current and zero-crossing current are sensed through the N-channel MOSFET. The core output voltage is measured at FBC through a resistive voltage-divider. This divider can be adjusted to set the output voltage level (see Setting the Output Voltages). The core input can be supplied from the main regulator or an external supply that does not exceed +5.5V (see High-Voltage Configuration and Low-Voltage Configuration sections). The core converter can be shut down independent of the main converter by driving SHDNC low. If the main converter output is supplying power to the core and is shut down, SHDNM controls both outputs. In this configuration, the core converter continues to operate when the MAX1774 is in backup mode.
MAX1774
Voltage Monitors and Battery Switchover
The MAX1774 offers voltage monitors ACI, LBI, DBI, and BKOFF that drive corresponding outputs to indicate low-voltage conditions. The AC adapter low-voltage detect input, ACI, is typically connected to the output of an AC-to-DC converter. When the voltage at ACI drops below the INS sense input plus 0.22V, the low AC output, ACO, is asserted. Figure 3 shows a simplified block diagram. The low and dead battery monitors (LBI and DBI) monitor the voltage at MAIN_BATT through a resistive voltage-divider. When the voltage at LBI falls below +1.20V, the low-battery output flag, LBO, is asserted. When both VIN_AC and MAIN_BATT are present, the MAX1774 chooses one of the two supplies determined by ACI. To facilitate this, the MAX1774 provides an open-drain MOSFET driver output (MDRV). This drives an external P-channel MOSFET used to switch the MAX1774 from the AC input to the battery. MDRV goes low when ACO is low, the main battery is not dead, and the MAX1774 is not in backup mode. The MAX1774 enters backup mode when the voltage at DBI is below +1.20V and VIN_AC is not present to the board. Under these conditions, the BKUP output is asserted (low), and the device utilizes its boost converter and a low-voltage backup battery to supply the main output. The BKUP pin can be driven low externally, forcing the MAX1774 to enter backup mode. If the voltage at BKOFF is less than 0.5V, the backup converter is disabled. BKOFF can be driven from a digital signal, or can be used as a low-battery detector to disable the backup converter when the backup battery is low.
Main Step-Down Converter
The main step-down converter features adjustable +1.25V to +5.5V output delivering up to 2A from a +2.7V to +28V input (see Setting the Output Voltages ). The use of external MOSFETs and current-sense resistor maximizes design flexibility. The MAX1774 offers a synchronous-rectifier MOSFET driver that improves efficiency by eliminating losses through a diode. The two MOSFET drive outputs, PDRV and NDRV, control these external MOSFETs. The output swing of these outputs is limited to reduce power consumption by limiting the amount of injected gate charge (see Internal Linear Regulators section for details). Current-limit detection for all main converter current limits is sensed through a small-sense resistor at the converters' output (see Setting the Current Limit section ). Driving the SHDNM pin low puts the main converter in a low-power shutdown mode. The core regulator, low-voltage detectors, and backup converter are still functional when the main converter is in shutdown. When the MAX1774 enters backup mode, the main converter and its current sensor are shut off.
Core Step-Down Converter
The core step-down converter produces a +1.0V to +5.0V output from a +2.6V to +5.5V input. The low-voltage input allows the use of internal power MOSFETs, taking advantage of their low RDS(ON), improving efficiency and reducing board space. Like the main converter, the core regulator makes use of a synchronousrectifying N-channel MOSFET, improving efficiency and
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
LBO LBO LBI 1.2V MDRV MDRV DBI 1.2V BKUP ACI INS NOAC 0.22V BKOFF 0.5V BKUP MODE ACO DBO BKUP
BIN
CS- (MAIN OUT)
CS+ MAIN RDY RDY REF CVL EN FB SOFT-START SHDNM SHDNC LXB2 (QFN ONLY) LXB BACKUP BOOST PGND FB MAX1774 EN CORE BUCK ON ON NDRV MAIN BUCK CVH CS- CS+ IN PDRV CVH
CVL REF
PGND
INC
LXC
FB PGNDC GND
FBM
FBC
Figure 3. Simplified Block Diagram
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15
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
Place 1M pullup resistors from the main output to ACO, LBO, and BKUP. Use a 1M pullup resistor from MDRV to IN. When not in backup mode, the backup regulator is isolated from the main output by an internal switch. When the MAX1774 is in backup mode, the main converter is disabled, and the output of the backup regulator is connected to the main output. The core converter is still operable while in backup mode. The backup step-up converter cannot drive the typical main load current. The load at main must be reduced before entering backup mode. If BKUP is de-asserted (goes high), the MAX1774 exits backup mode and resumes operation from the main battery or the AC adapter input. If BKOFF goes low, or the backup battery discharges where it cannot sustain the main output load, the backup converter shuts off. To restart the main converter, apply power to VIN_AC or MAIN_BATT. The backup converter uses an external Schottky diode and internal power NMOS switch. Since this converter shares the same output as the main buck converter, it shares the same feedback network. This automatically sets the backup converter output voltage to that of the main converter. The backup converter generates an output between +1.25V and +5.5V from a +0.9V to +5.5V input, and provides a load current up to 20mA. When the MAX1774 is in backup mode, the main current- sense circuit is turned off to conserve power. When the output is out of regulation, the maximum inductor current limit and zero-current detectors regulate switching. The N-channel MOSFET is turned on until the maximum inductor current limit is reached, and shuts off until the inductor current reaches zero. When the output is within regulation, switching is controlled by the maximum pulse width, LXB, switch current limit, zero crossing, and the feedback voltage.
MAX1774
Reference
The MAX1774 has a trimmed internal +1.25V reference at REF. REF can source no more than 50A. Bypass REF to GND with a 0.22F capacitor.
Design Procedure
Low-Voltage Configuration
To improve efficiency and conserve board space, the core regulator operates from low input voltages, taking advantage of internal low-voltage, low-on-resistance MOSFETs. When the input voltage remains below 5.5V, run the core converter directly from the input by connecting INC to IN (Figure 1). This configuration takes advantage of the core's low-voltage design and improves efficiency.
High-Voltage Configuration
For input voltages greater than 5.5V, cascade the main and core converters by connecting INC to the main output voltage (Figure 4). In this configuration, the core converter is powered from the main output. Ensure that the main output can simultaneously supply its load and the core input current.
Backup Converter Configuration
The MAX1774 provides a backup step-up converter to power the device and provide the main output voltage when other power fails. The backup converter operates from a +0.9V to +5.5V battery. For most rechargeable batteries, such as NiCd or NiMH, the simple circuit of Figure 5 can be used to recharge the backup battery. In this circuit, the backup battery is charged through R1 and D10. Consult the battery manufacturer for charging requirements. To prevent the backup battery from overdischarging, connect a resistive voltagedivider from the backup battery to BKOFF. Resistor values can be calculated through the following equation: R12 = R13 [(VBU / V BKOFF) - 1] where V BKOFF = 0.5V, and VBU is the minimum acceptable backup battery voltage. Choose R13 to be less than 150k.
Internal Linear Regulators
There are two internal linear regulators in the MAX1774. A high-voltage linear regulator accepts inputs up to +28V, reducing it to +2.8V at CVL to provide power to the MAX1774. If the voltage at CS- is greater than +2.47V, CVL is switched to CS-, allowing it to be driven from the main converter, improving efficiency. CVL supplies the internal bias to the IC and power for the NDRV gate driver. The CVH regulator output provides the low-side voltage for the main regulator's PDRV output. The voltage at CVH is regulated at 4.2V below VIN to limit the voltage swing on PDRV, reducing gate charge and improving efficiency (Figure 3).
16
Setting the Output Voltages
The main output voltage is set from +1.25V and +5.5V with two external resistors connected as a voltagedivider to FBM (Figure 1). Resistor values can be calculated by the following equation: R10 = R11 [(VOUTM / VFBM) - 1] where VFBM = +1.25V. Choose R11 to be 40k or less. The core regulator output is adjustable from +1.0V to +5.0V through two external resistors connected as a
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
2.7V TO 28V VIN_AC D1 NSD03A10 C5 1F IN R4 MDRV DBI PDRV R2 N1 LBI R3 NDRV P2 FDS8928A L1 5H RCS MAIN CMAIN 47F ACI INS CVH C6 10F MAIN BATTERY 2.7V TO 20V
NDS356AP
P1 1M R1
2.6V TO 5.5V
MAX1774
PGND ON SHDNM SHDNC BIN CS+ CS-
OFF ON OFF C1 10F D2 EP05 Q03L L3 22H BKOFF C2 10F C3 1F C4 0.22F REF GND PGNDC CVL
R10 LXB LXB2 (QFN ONLY) FBM R11 R5 1M ACO R6 1M LBO R7 1M BKUP INC C7 1F L2 5.4H LXC R8 FBC R9 CORE
BACKUP BATTERY 0.9V TO 5.5V
1.0V CCORE TO 22F 5.5V
Figure 4. Typical Application Circuit (Cascaded)
voltage-divider to FBC (Figure 1). Resistor values can be calculated with the following equation: R8 = R9 [(VOUTC / VFBC) - 1] where VFBC = +1.0V. Choose R9 to be 30k or less.
RCS = VCLM / (1.3 IOUT) where VCLM = 80mV is the current-sense threshold, and IOUT is the current delivered to the output. The core and backup converter current limits are set internally and cannot be modified. Careful layout of the current-sense signal traces is imperative. Place RCS as close to the MAX1774 as possible. The two traces should have matching length and width, be as far as possible from noisy switching sig17
Setting the Current Limit
The main regulator current limit is set externally through a small current-sense resistor, R CS (Figure 1). The value of RCS can be calculated with the following equation:
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
2.7V TO 28V VIN_AC MAIN BATTERY 2.7V TO 20V D1 NSD03A10 C5 IN P1 R1 MDRV DBI PDRV R2 N1 LBI ACI R3 1M PGND R12 OFF ON OFF BIN C1 10F D2 EP05 Q03L L3 22H BACKUP BATTERY 0.9V TO 5.5V C2 10F C3 REF C4 0.22F GND PGNDC L2 LXC R8 FBC R9 CCORE 22F BKUP INC C7 1F CORE 1.0V TO 5.5V R10 LXB FBM LXB2 (QFN ONLY) R11 R13 BKOFF ACO CVL LBO R7 1M R6 1M R5 1M SHDNC ON SHDNM CS+ CSNDRV P2 FDS8928A L1 10H RCS MAIN CMAIN 47F 2.6V TO 5.5V R4 INS CVH C6 10F
NDS356AP
MAX1774
Figure 5. Typical Application Circuit (with Recharge)
nals, and be close together to improve noise rejection. These traces should be used for current-sense signal routing only and should not carry any load current. Refer to the MAX1774 evaluation kit for layout examples.
divider string (R1, R2, and R3) in Figure 1 according to the following equations: R1 = (R2 + R3) [(VBD / VTH) - 1] R2 = R3 [(VBL / VBD) - 1] where VBL is the low battery voltage, VBD is the dead battery voltage, and VTH = +1.20V. Choose R3 to be less than 250k.
Setting the Voltage Monitor Levels
The low battery and dead battery detector trip points can be set by adjusting the resistor values of the
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
Inductor Selection
The essential parameters for inductor selection are inductance and current rating. The MAX1774 operates with a wide range of inductance values. Calculate the inductance value for either CORE or MAIN, LMIN : L(MIN) = (VIN - VOUT) (tON(MIN) / lRIPPLE) where tONMIN is typically 400ns, and lRIPPLE is the continuous conduction peak-to-peak lRIPPLE current. In continuous conduction, lRIPPLE should be chosen to be 30% of the maximum load current. With high inductor values, the MAX1774 begins continuous-conduction operation at a lower fraction of full load (see Detailed Description). The inductor's saturation current must be greater than the peak switching current to prevent core saturation. Saturation occurs when the inductor's magnetic flux density reaches the maximum level the core can support and inductance starts to fall. The inductor heating current rating must be greater than the maximum load current to prevent overheating. For optimum efficiency, the inductor series resistance should be less than the current-sense resistance. Also, ensure that the tantalum capacitors' surge-current ratings exceed the startup inrush and peak switching currents. The input filter capacitor reduces peak currents drawn from the power source and reduces noise and voltage ripple at IN, caused by the circuit's switching. Use a low-ESR capacitor. Two smaller value low-ESR capacitors can be connected in parallel if necessary. Choose input capacitors with working voltage ratings higher than the maximum input voltage.
MAX1774
MOSFET Selection
The MAX1774 drives an external enhancement-mode Pchannel MOSFET and a synchronous-rectifier N-channel MOSFET. When selecting the MOSFETs, important parameters to consider are on-resistance (RDS(ON)), maximum drain-to-source voltage (V DS(MAX) ), maximum gate-to-source voltage (V GS(MAX) ), and minimum threshold voltage (VTH(MIN)).
Chip Information
TRANSISTOR COUNT: 4545 PROCESS: BiCMOS
Capacitor Selection
Choose the output filter capacitors to service input and output ripple current with acceptable voltage ripple. ESR in the output capacitor is a major contributor to output ripple. For the main converter, low-ESR capacitors such as polymer or ceramic capacitors are recommended. For the core converter, choosing a low-ESR tantalum capacitor with enough ESR to generate about 1% ripple voltage across the output is helpful in ensuring stability. Voltage ripple is the sum of contributions from ESR and the capacitor value: VRIPPLE VRIPPLE,ESR + VRIPPLE,C For tantalum capacitors, the ripple is determined mostly by the ESR. Voltage ripple due to ESR is: VRIPPLE,ESR (RESR) IRIPPLE For ceramic capacitors, the ripple is mostly due to the capacitance. The ripple due to the capacitance is approximately: VRIPPLE,C L IRIPPLE2COUT VOUT where VOUT is the average output voltage. These equations are suitable for initial capacitor selection. Final values should be set by testing a prototype or evaluation kit. When using tantalum capacitors, use good soldering practices to prevent excessive heat from damaging the devices and increasing their ESR.
Pin Configurations (continued)
TOP VIEW
SHDNM 1 SHDNC 2 BKUP 3 MDRV 4 PGNDC 5 PGND 6 NDRV 7 CVL 8 IN 9 PDRV 10 CVH 11 LXB 12 BIN 13 BKOFF 14 28 LXC 27 INS 26 LBO 25 ACO 24 INC
MAX1774
23 GND 22 FBC 21 CS20 CS+ 19 FBM 18 REF 17 LBI 16 DBI 15 ACI
28 QSOP
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19
Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover MAX1774
Package Information
QFN 28, 32,44, 48L.EPS
20
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Dual, High-Efficiency, Step-Down Converter with Backup Battery Switchover
Package Information (continued)
QSOP.EPS
MAX1774
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
21 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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