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19-2165; Rev 0; 10/01
MAX1813 Evaluation Kit
General Description
The MAX1813 evaluation kit (EV kit) demonstrates the high-power, dynamically adjustable notebook CPU application circuit. This DC-DC converter steps down high-voltage batteries and/or AC adapters, generating a precision, low-voltage CPU core VCC rail. The MAX1813 EV kit meets the Intel mobile CPU's transient voltage specification (IMVP-II/Coppermine), using voltage positioning to minimize the output-capacitor requirements. The MAX1813 has an internal multiplexer which accepts three unique 5-bit VID DAC codes corresponding to performance, battery, and suspend modes. Precision slew-rate control provides "just-intime" arrival at the new DAC setting, minimizing surge currents to and from the battery. This fully assembled and tested circuit board provides a digitally adjustable 0.6V to 2.0V output from a 7V to 24V battery input range. It delivers up to 22A output current. The EV kit operates at 300kHz switching frequency and has superior line- and load-transient response.
Features
o High Speed, Accuracy, and Efficiency o IMVP-II/Coppermine/AMD Compatible o Voltage-Positioned Output o Low Output-Capacitor Count (6) o Fast-Response Quick-PWMTM Architecture o 7V to 24V Input Voltage Range o 0.925V to 2.0V Output Voltage Range (Coppermine/AMD, 5-Bit DAC) o 0.6V to 1.75V Output Voltage Range (IMVP-II, 5-Bit DAC) o 22A Load-Current Capability o 300kHz Switching Frequency o Power Good (PGOOD) Indicator o 28-Pin QSOP Package o Low-Profile Components o Fully Assembled and Tested
Evaluates: MAX1813
Ordering Information
PART MAX1813EVKIT TEMP. RANGE 0C to +70C IC PACKAGE 28 QSOP
Component List
DESIGNATION QTY DESCRIPTION 10F, 25V ceramic capacitors (1812) Taiyo Yuden TMK432BJ106KM TDK C4532X5R1E106M 220F, 2.5V, 15m low-ESR specialty polymer capacitors Panasonic EEFUE0E221R 10F, 6.3V X5R ceramic capacitor (1210) Taiyo Yuden JMK325BJ106MN TDK C3216X5R0J106M 0.1F ceramic capacitor (0805) 0.22F, 16V X5R ceramic capacitors (0805) Taiyo Yuden EMK212BJ224KG DESIGNATION C14 QTY 1 DESCRIPTION 47pF ceramic capacitor (0805) 1F, 10V X5R ceramic capacitor (0805) Taiyo Yuden LMK212BJ105KG TDK C2012X5R105M 1000pF ceramic capacitors (0805) 4700pF ceramic capacitors (0805) Not installed 5A Schottky diode Central Semiconductor CMSH5-40 100mA Schottky diode Central Semiconductor CMPSH-3
C1-C4, C20
5
C15
1
C5, C6, C7, C10, C13, C16
6
C18, C27 C17, C19, C23, C24, C25 C21, C22, C26 D1
2 5 0 1
C8 C9 C11, C12
1 1 2
D2
1
Quick-PWM is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 1
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.
MAX1813 Evaluation Kit Evaluates: MAX1813
Component List (continued)
DESIGNATION D3 QTY 1 DESCRIPTION 200mA Switching diode Central Semiconductor CMPD2838 Scope probe connector Berg Electronics 33JR135-1 4-pin headers 3-pin header 2-pin headers Not installed 0.68H power inductor Toko EH125C-R60N or Sumida CEP125 #4712-T011 or Sumida CDEP134H-0R6 or Panasonic ETQP6F0R6BFA N-channel MOSFETs (SO-8) International Rectifier IRF7811W International Rectifier IRF7811 N-channel MOSFETs (SO-8) International Rectifier IRF7822 Fairchild FDS7764A 20 5% resistor (0805) 100k 5% resistors (0805) Not installed (short PC trace) (0805) 100 5% resistors (0805) 0.0015 5% 1W resistor (2512) Panasonic ERJM1WTJ1M5U 10k 5% resistors (0805) 51.1k 1% resistor (0805) 20k 5% resistor (0805) 300k 5% resistor (0805) 200k 5% resistor (0805) Not installed (0805) 150k 5% resistor (0805) Not installed (2512) DIP-8 dip switch MAX1813EEI (28-QSOP) SUPPLIER Central Semiconductor Fairchild International Rectifier Panasonic Sumida Taiyo Yuden TDK Toko DESIGNATION None None None None None QTY 12 4 1 1 1 DESCRIPTION Shunts Rubber bumpers 3M SJ-5007, Mouser 517-SJ5007BK or equivalent MAX1813 PC board MAX1813 data sheet MAX1813 EV kit data sheet
J1 JU1, JU2 JU8 JUA0-JUA4, JUB0-JUB4 JU3, JU4, JU5, JU6
1 2 1 10 0
Component Suppliers
PHONE 516-435-1110 408-721-2181 310-322-3331 714-373-7939 708-956-0666 408-573-4150 847-390-4373 408-432-8281 FAX 516-435-1824 408-721-1635 310-322-3332 714-373-7183 708-956-0702 408-573-4159 847-390-4428 408-943-9790
L1
1
N1, N2
2
N3, N4, N5 R1 R2-R6, R9, R22-R27 R7 R8, R11 R12 R13, R28 R14 R15 R16 R17 R18, R19 R20 R29 SW1 U1
3 1 13 0 2 1 2 1 1 1 1 0 1 1 1 1
Recommended Equipment
* 7V to 24V, >30W power supply, battery, or notebook AC adapter * DC bias power supply, 5V at 100mA * Dummy load capable of sinking 22A * Digital multimeter (DMM) * 100MHz dual-trace oscilloscope
Quick Start
1) Ensure that the circuit is connected correctly to the supplies and dummy load prior to applying any power. 2) Set switches SW1-A (SHDN) and SW1-C (ZMODE) to the ON position, and SW1-B (SKIP) to the OFF position. This configures the EV kit for fixed-frequency PWM-mode operation. The DAC code settings (D4-D0) are set for 1.30V output for the impedancemode configuration through jumpers JUB4, JUB2, and JUB1, and to 1.15V output for the logic mode configuration through installed jumpers JUA4, JUA1, and JUA0 (CODE = 1, JU8 pins 1 and 2). 3) Turn on the battery power before turning on the 5V bias power; otherwise, the output UVLO timer will time out, and the FAULT latch will be set, disabling the regulator until 5V power is cycled or shutdown is toggled.
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MAX1813 Evaluation Kit
4) Observe the 1.30V output voltage with the DMM and/or oscilloscope. Look at the LX switching-node and MOSFET gate-drive signals while varying the load current. 5) Toggle the ZMODE switch, and observe the output voltage transition to the new 1.15V setting. Note: When driving ZMODE with the dip switch, the transition may take longer than expected due to switch bounce. kit is configured for operation in the impedance mode with jumpers JUB0-JUB4 set for 1.30V output (Table 1). While in the impedance mode, changing jumpers JUB0-JUB4 does not immediately change the output voltage setting. SHDN, ZMODE, SUS, or VBIAS must be cycled to sample the new jumper settings. Refer to the MAX1813 data sheet for more information. 4) Install jumpers JU1 and JU2 (suspend-mode configuration: SW1-D ON, SUS = high). As shipped, the EV kit is configured for operation in the suspend mode with jumpers JU1 and JU2 set for 0.85V output (Table 2). In the suspend mode, change the output voltage during operation by installing and removing jumpers JU1 and JU2. Refer to the MAX1813 data sheet for more information.
Evaluates: MAX1813
Detailed Description
This 22A buck-regulator design is optimized for a 300kHz frequency and output voltage settings around 1.15V to 1.3V. At VOUT = 1.3V, inductor ripple is approximately 30%.
Setting the Output Voltage
The MAX1813 has a unique internal multiplexer that can select one of three different VID DAC code settings for different processor states. Depending on the logic level at SUS (SW1-D), the suspend mode multiplexer selects the VID DAC code settings from either the ZMODE multiplexer, or the S0/S1 (JU1, JU2) input decoder. The output voltage can be digitally set from 0.925V to 2.0V (Table 1, CODE = 0, JU8 pins 2 and 3) or from 0.6V to 1.75V (Table 1, CODE = 1, JU8 pins 1 and 2) from the D0-D4 pins, and from 0.6V to 0.975V (Table 2) from S0/S1 pins. There are four different ways of setting the output voltage: 1) Drive the external VID0-VID4 inputs (no jumpers installed). Set the output voltage by driving the VID0-VID4 with open-drain drivers (pullup resistors are included on the board) or 3V/5V CMOS output logic levels. The internal multiplexer must be in the logic-mode configuration (ZMODE = low, SUS = low) 2) Install jumpers JUA0-JUA4 (logic-mode configuration: SW1-C OFF, ZMODE = low, and SW-D OFF, SUS = low). When JUA0-JUA4 are not installed, the MAX1813's D0-D4 inputs are at logic 1 (connected to VCC). When JUA0-JUA4 are installed, D0-D4 inputs are at logic 0 (connected to GND). In the logic-mode configuration, change the output voltage during operation by installing and removing jumpers JUA0-JUA4. As shipped, the EV kit is configured for operation in the logic mode with jumpers JUA0-JUA4 set for 1.15V output (Table 1). 3) Install jumpers JUB0-JUB4 (impedance-mode configuration: SW1-C ON, ZMODE = high, and SW1-D OFF, SUS = low). When JUB0-JUB4 are not installed, a 100k resistor is in series with each of the D0-D4 inputs, making it a logic 1. When JUB0-JUB4 are installed, the 100k resistors are shorted, making D0-D4 logic 0. As shipped, the EV
Dynamic Output Voltage Transition Experiment
Observe the output voltage transition between: 1) 0.85V and 1.15V by setting SW1-C OFF (ZMODE = low) and toggling SW1-D (SUS) position between ON and OFF. 2) 1.15V and 1.30V by toggling the SW1-C (ZMODE) position between ON and OFF (SW1-D OFF, SUS = low). 3) 0.85V and 1.30V by setting SW1-C ON (ZMODE = high) and toggling SW1-D (SUS) position between ON and OFF. This is the worst-case transition and should complete within 100s. This EV kit is set to transition the output voltage at 8.8mV/s. Alter the speed of the transition by changing resistor R14 (51.1k). Longer-than-expected transitions maybe observed due to switch bounce (SW1). To eliminate switch bounce, set SW1-D (SUS) to the OFF position, and drive the SUS pin (TP2) with a function generator. During the voltage transition, watch the inductor current by looking across R12 with a differential scope probe or by inserting a current probe in series with the inductor. Observe the low, well-controlled inductor current that accompanies the voltage transition. The same slew rate and controlled inductor current are used during shutdown and start up, resulting in well-controlled currents into and out of the battery (input source).
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3
MAX1813 Evaluation Kit Evaluates: MAX1813
Table 1. MAX1813 Output Voltage Adjustment Settings
D4 JUA4 JUB4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D3 JUA3 JUB3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D2 JUA2 JUB2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D1 JUA1 JUB1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D0 JUA0 JUB0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 OUTPUT VOLTAGE CODE = 0 (JU8 PINS 2 AND 3) 2.000V 1.950V 1.900V 1.850V 1.800V 1.750V 1.700V 1.650V 1.600V 1.550V 1.500V 1.450V 1.400V 1.350V 1.300V NO CPU* 1.275V 1.250V 1.225V 1.200V 1.175V 1.150V 1.125V 1.100V 1.075V 1.050V 1.025V 1.000V 0.975V 0.950V 0.925V NO CPU* OUTPUT VOLTAGE CODE = 1 (JU8 PINS 1 AND 2) 1.750V 1.700V 1.650V 1.600V 1.550V 1.500V 1.450V 1.400V 1.350V 1.300V 1.250V 1.200V 1.150V 1.100V 1.050V 1.000V 0.975V 0.950V 0.925V 0.900V 0.875V 0.850V 0.825V 0.800V 0.775V 0.750V 0.725V 0.700V 0.675V 0.650V 0.625V 0.600V
*In the no-CPU state, DH and DL are held low and the slew-rate controller is set for 0.425V.
4
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MAX1813 Evaluation Kit
There are two other methods to create an output voltage transition. Select D0-D4 logic mode by setting the ZMODE switch to the OFF position (SW1-C). Then either manually change the JUA0-JUA4 jumpers to a new VID code setting (Table 1), or remove all jumpers and drive the VID0-VID4 PC board test points externally to the desired code settings.
Evaluates: MAX1813
Table 2. Output Voltage Adjustment Settings, Suspend Mode
SHUNT LOCATION JU2 1, 2 1, 2 1, 2 1, 2 1, 3 1, 3 1, 3 1, 3 Not installed Not installed Not installed Not installed 1, 4 1, 4 1, 4 1, 4 SHUNT LOCATION JU1 1, 2 1, 3 Not installed 1, 4 1, 2 1, 3 Not installed 1, 4 1, 2 1, 3 Not installed 1, 4 1, 2 1, 3 Not installed 1, 4 S1 PIN GND GND GND GND REF REF REF REF OPEN OPEN OPEN OPEN VCC VCC VCC VCC S0 PIN GND REF OPEN VCC GND REF OPEN VCC GND REF OPEN VCC GND REF OPEN VCC OUTPUT VOLTAGE 0.975V 0.950V 0.925V 0.900V 0.875V 0.850V 0.825V 0.800V 0.775V 0.750V 0.725V 0.700V 0.675V 0.650V 0.625V 0.600V
Load-Transient Experiment
One interesting experiment is to subject the output to large, fast-load transients and observe the output with an oscilloscope. This necessitates careful instrumentation of the output, using the supplied scope-probe jack. Accurate measurement of output ripple and load-transient response invariably requires that ground clip leads be completely avoided and that the probe be removed to expose the GND shield, so the probe can be plugged directly into the jack. Otherwise, EMI and noise pickup will corrupt the waveforms. Most benchtop electronic loads intended for powersupply testing lack the ability to subject the DC-DC converter to ultra-fast load transients. Emulating the supply current di/dt at the CPU VCORE pins requires at least 10A/s load transients. One easy method for generating such an abusive load transient is to solder a power MOSFET directly across the scope-probe jack. Then drive its gate with a strong pulse generator at a low duty cycle (10% or less) to minimize heat stress in the MOSFET. Vary the high-level output voltage of the pulse generator to vary the load current. To determine the load current, one might expect to insert a meter in the load path, but this method is prohibited here by the need for low resistance and inductance in the path of the dummy load MOSFET. There are two easy alternative methods of determining how much load current a particular pulse-generator amplitude is causing. The first and best is to observe the inductor current with a calibrated AC current probe,
such as a Tektronix AM503 or by looking across R12 with a differential probe. In the buck topology, the load current is equal to the average value of the inductor current. The second method is to put on a static dummy load and measure the battery current. Then connect the MOSFET dummy load at 100% duty momentarily and adjust the gate-drive signal until the battery current rises to the appropriate level (the MOSFET load must be well heat-sinked for this to work without causing smoke and flames).
Table 3. Switch SW1-A/SW1-B Functions (SHDN, SKIP)
SW1-A OFF SW1-B X CONNECTION SKIP, SHDN connected to GND through R15 and R17 EFFECT Shutdown mode, VOUT = 0V Output enabled. SKIP mode operation. Allows automatic PWM/PFM switchover for pulse skipping at light-load for highest efficiency. Refer to the Forced PWM Mode section in the MAX1813 data sheet for more information. Output enabled. Low-noise mode. Forced fixed-frequency PWM operation. Recommended for output voltage transitions.
ON
ON
SKIP, SHDN connected to VCC through R15
ON
OFF
SKIP, SHDN connected to +2V through R15 and divider R16/R17
_______________________________________________________________________________________
5
MAX1813 Evaluation Kit Evaluates: MAX1813
Table 4. Switch SW1-C/SW1-D Functions (ZMODE, SUS for IMVP II, Code = 1)
SW1-C ON OFF X SW1-D OFF OFF ON CONNECTION ZMODE connected to VCC, SUS connected to GND ZMODE connected to GND, SUS connected to GND SUS connected to VCC INTERNAL MULTIPLEXER Impedance Mode Logic Mode Suspend Mode
Table 5. Jumpers JU3/JU4/JU5 Functions (Switching-Frequency Selection)
SHUNT LOCATION JU3 Installed Not Installed Not Installed Not Installed JU4 Not Installed Installed Not Installed Not Installed JU5 Not Installed Not Installed Installed Not Installed TON PIN Connected to VCC Connected to REF Connected to GND Floating FREQUENCY (kHz) 200 550 1000 300 (as shipped)
IMPORTANT: Don't change the operating frequency without first recalculating component values. The frequency has a significant effect on the inductor peak current, MOSFET heating, preferred inductor value, PFM/PWM switchover point, output noise, efficiency, and other critical parameters.
Table 6. Jumper JU6 Functions (Fixed/Adjustable Current-Limit Selection)
SHUNT POSITION ON ILIM PIN Connected to VCC Connected to an external resistor divider, R18/R19. Refer to the Pin Description ILIM section in the MAX1813 data sheet for more information. CURRENT-LIMIT THRESHOLD 50mV (default)
OFF
Adjustable between 50mV to 200mV.
6
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MAX1813 Evaluation Kit Evaluates: MAX1813
Table 7. Troubleshooting Guide
SYMPTOM Circuit won't start when power is applied. POSSIBLE PROBLEM Power-supply sequencing: 5V bias supply was applied before battery voltage. Output overvoltage due to shorted high-side MOSFET Output overvoltage due to load recovery overshoot Output overload condition Broken connection, bad MOSFET, or other catastrophic problem On-time pulses are erratic or have unexpected changes in period. SOLUTION Cycle SW1-A SHDN. Replace the MOSFET. Reduce the inductor value, raise the switching frequency, or add more output capacitance. Remove excessive load. Troubleshoot the power stage. Are the DH and DL gate-drive signals present? Is the 2V VREF present? Add a bulk electrolytic bypass capacitor across the benchtop power supply, or substitute a real battery. Observe the gate-source voltage of N3/N4/N5 during the low-to-high LX node transition (this requires careful instrumentation). Is the gate voltage being pulled above 1.5V, causing N3/N4/N5 to turn on? Use a smaller low-side MOSFET or add a BST resistor (R7). Use a smaller/faster high-side MOSFET or add more heatsinking.
Circuit won't start when +5V bias supply cycled.
VBATT power source has poor impedance characteristic.
Excessive EMI, poor efficiency at high input voltages.
Gate-drain capacitance of N3/N4/N5 is causing shoot-through cross-conduction.
Poor efficiency at high input voltages, N1/N2 get hot.
N1/N2 has excessive gate capacitance.
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7
Evaluates: MAX1813
MAX1813 Evaluation Kit
Figure 1. MAX1813 EV Kit Schematic
VCC C11 0.22F R1 20 VDD 21 D4 D3 D2 D1 BST 123 28 C9 0.1F LX TP1 3 SKP/SDN DL 123 C5 220F 2.5V 123 123 C7 220F 2.5V C13 220F 2.5V C26 OPEN GND C27 1000pF R11 100 VCC C18 1000pF R4 100k PGOOD VCC R12 1.5m R29 OPEN 4 TIME 2 R8 100 16 4 4 4 N3 D1 N4 N5 R14 51.1k 1% C14 47pF 6 CC VPCS R20 150k 11 REF FB 5 5678 5678 5678 C6 220F 2.5V C10 220F 2.5V 27 L1 0.68H D3 VOUT C16 220F 2.5V C8 10F 6.3V VDD 321 4 4 J1 SCOPE JACK D0 DH 26 N1 N2 D2 CMPSH-3 5678 8765 C15 1F R7 SHORT (PC TRACE) V+ VBATT 22 23 24 25 TP3 19 ZMODE 1 +5V VBIAS C21 OPEN C22 OPEN VDD C1 10F 25V C2 10F 25V C3 10F 25V C4 10F 25V C20 10F 25V D4 D3 D2 D1 D0 R13 10k R15 20k
8
U1 MAX1813
JU4 550kHz FLOAT = 300kHz 10 TON CODE 20 JU8 1 2 3 VCC JU5 1MHz R18 OPEN JU6 12 ILIM GND 14 PGOOD 13 C12 0.22F VCC 7 S0 TP2 SUS S1 PGND 15 18 R28 10k VCC SW1-D R27 SUS 100k VCC 2 4 JU2 3 1 8 2 R19 OPEN 4 JU1 1
VBATT 7V TO 24V
VCC
6
3
SW1-A SHDN
8
SW1-C ZMODE
R27 100k
1
7
2
R16 300k
SW1-B SKIP
R17 200k
REF 2V
VCC
JU3 200kHz
REF
REF
3
_______________________________________________________________________________________
REF
VCC R26 100k C25 4700pF R2 100k D4 JUA4 VID4
JUB4
VCC R25 100k C24 4700pF R3 100k D3 JUA3 VID3
Figure 1. MAX1813 EV Kit Schematic (continued)
JUB3 VCC R24 100k C23 4700pF VID2 JUA2 R5 100k D2 JUB2 VCC R23 100k VID1 JUA1 C19 4700pF JUB1 R6 100k D1 VCC R22 100k VID0 JUA0 C17 4700pF JUB0 R9 100k D0
Evaluates: MAX1813
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MAX1813 Evaluation Kit
9
MAX1813 Evaluation Kit Evaluates: MAX1813
1.0"
1.0"
Figure 2. MAX1813 EV Kit Component Placement Guide--Top Silkscreen
Figure 3. MAX1813 EV Kit PC Board Layout--Component Side
1.0"
1.0"
Figure 4. MAX1813 EV Kit PC Board Layout--Ground Layer 2
Figure 5. MAX1813 EV Kit PC Board Layout--Ground Layer 3
10
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MAX1813 Evaluation Kit Evaluates: MAX1813
1.0"
1.0"
Figure 6. MAX1813 EV Kit PC Board Layout--Solder Side
Figure 7. MAX1813 EV Kit Component Placement Guide -- Bottom Silkscreen
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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