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19-3350; Rev 0; 7/04
Silicon Oscillator with Low-Power Frequency Switching and Reset Output
General Description
The MAX7378 dual-speed silicon oscillator with reset, is a replacement for ceramic resonators, crystals, crystaloscillator modules, and discrete reset circuits. The MAX7378 provides the primary and secondary clock source and reset function for microcontrollers in 3V, 3.3V, and 5V applications. The MAX7378 features a factory-programmed high-speed oscillator, a 32.768kHz oscillator, a clock selector input, and a microprocessor (P) power-on-reset (POR) supervisor. The clock output can be switched at any time between the high-speed clock and the 32.768kHz clock for lowpower operation. Switchover is synchronized internally to provide glitch-free clock switching. Unlike typical crystal and ceramic resonator oscillator circuits, the MAX7378 is resistant to vibration and EMI. The high-output-drive current and absence of highimpedance nodes make the oscillator less susceptible to dirty or humid operating conditions. With a wide operating temperature range as standard, the MAX7378 is a good choice for demanding home appliance, industrial, and automotive environments. The MAX7378 is available in an 8-pin MAX(R) package. Refer to the MAX7384 data sheet for frequencies 10MHz. The MAX7378 standard operating temperature range is -40C to +125C. See the Applications Information section for the extended operating temperature range.
Features
2.7V to 5.5V Operation Accurate High-Speed Oscillator: 600kHz to 10MHz Accurate Low-Speed 32kHz Oscillator Glitch-Free Switch Between High Speed and Low Speed at Any Time Reset Output Holds the C in Reset for 100s After Clock Startup 10mA Clock-Output Drive Capability 2% Initial Accuracy 50ppm/C Temperature Coefficient 50% 7% Output Duty Cycle 5ns Output Rise and Fall Time Low Jitter: 160ps (Peak-to-Peak) at 8MHz 2.4mA Fast-Mode Operating Current (8MHz) 11A Slow-Mode Operating Current (32kHz) -40C to +125C Temperature Range
MAX7378
Ordering Information
PART MAX7378A _ _ _ MAX7378B _ _ _ TEMP RANGE -40oC to +125oC -40oC to +125oC RESET OUTPUT Active high push-pull Active low push-pull PINPACKAGE 8 MAX 8 MAX 8 MAX
Applications
White Goods Automotive Consumer Products Appliances and Controls Handheld Products Portable Equipment Microcontroller (C) Systems
MAX7378C _ _ _ -40oC to +125oC Open drain
Standard version is shown in bold. The first letter after the part number designates the reset output option. Insert the letter corresponding to the desired reset threshold level from Table 1 in the next position. Insert the two-letter code from Table 2 in the remaining two positions for the desired frequency range. See Table 3 for standard part numbers.
Typical Application Circuit
SUPPLY VOLTAGE
VCC ENABLE
VL CLOCK
OSC1 OSC2
Pin Configuration appears at end of data sheet.
MAX7378
RST/RST
RST I/O PORT SPEED
C
MAX is a registered 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.
Silicon Oscillator with Low-Power Frequency Switching and Reset Output MAX7378
ABSOLUTE MAXIMUM RATINGS
VCC to GND .............................................................-0.3V to +6V All Other Pins to GND ................................-0.3V to (VCC + 0.3V) CLOCK Current ................................................................10mA Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 4.5mW/C above +70C)....362mW (U8-1) Operating Temperature Range .........................-40C to +135C Junction Temperature .....................................................+150C Storage Temperature Range.............................-60C to +150C Lead 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
(VCC = 2.7V to 5.5V, VL = VCC, TA = -40C to +125C, unless otherwise noted. Typical values are at VCC = 5V, TA = +25C.) (Note 1)
PARAMETER Operating Supply Voltage Logic Output Supply Voltage Operating Supply Current Shutdown Current LOGIC INPUT (SPEED, ENABLE) Input High Voltage Input Low Voltage Input Current CLOCK OUTPUT VL = 4.5V, ISOURCE = 9mA Output High Voltage VOH VL = 2.7V, ISOURCE = 2.5mA Output Low Voltage Initial Fast CLOCK Frequency Accuracy Fast CLOCK Frequency Temperature Sensitivity Initial Slow CLOCK Frequency Accuracy Slow CLOCK Frequency Temperature Sensitivity fSCLOCK VOL fFCLOCK VL = 4.5V, ISINK = 20mA VL = 2.7V, ISINK = 10mA VCC = 5V, TA = +25C (Note 2) VCC = 2.7V to 5.5V, TA = +25C (Note 3) VCC = 5V, TA = +25C VCC = 2.7V to 5.5V, TA = +25C (Note 3) 32.440 31.785 50 -2 -4 50 32.768 VL 0.4 V VL 0.4 0.4 0.4 +2 +4 325 33.096 33.751 325 V % ppm/oC kHz ppm/oC VIH VIL IIN 0.7 x VCC 0.3 x VCC 2 V V A SYMBOL VCC VL ICC + IL ICC + IL ISHDN Must be connected to VCC fCLOCK = 8MHz, no load fCLOCK = 32.768kHz, no load ENABLE = 0V; ICC + IL CONDITIONS MIN 2.7 2.7 2.4 11 3.0 TYP MAX 5.5 5.5 5.5 25 7.5 UNITS V V mA A A
2
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Silicon Oscillator with Low-Power Frequency Switching and Reset Output
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 2.7V to 5.5V, VL = VCC, TA = -40C to +125C, unless otherwise noted. Typical values are at VCC = 5V, TA = +25C.) (Note 1)
PARAMETER CLOCK Output Duty Cycle CLOCK Output Jitter CLOCK Output Rise Time CLOCK Output Fall Time RST/RST OUTPUT TA = +25C Reset Threshold VTH+ VCC rising TA = -40C to +125C Reset Hysteresis POR Delay Output High Voltage Output Low Voltage VOH VOL VTHYS VHYST = {(VTH+) - ( VTH-)}/(VTH-) x 100% VCC rising from 0V to (VTH +200mV) in 1s VL = 4.5V, ISOURCE = 9mA VL = 2.7V, ISOURCE = 2.5mA VL = 4.5V, ISINK = 20mA VL = 2.7V, ISINK = 10mA VL - 0.4 VL - 0.4 0.4 0.4 VTH 1.5% VTH 5% 2.0 100 VTH + 1.5% V VTH + 5% % s V V tR tF Observation of 8MHz output for 20s using a 500MHz oscilloscope 10% to 90% 90% to 10% SYMBOL CONDITIONS MIN 43 TYP 50 160 5 5 MAX 57 UNITS % psP-P ns ns
MAX7378
Note 1: All parameters are tested at TA = +25C. Specifications over temperature are guaranteed by design. Note 2: The frequency is determined by part number selection. See the Ordering Information. Note 3: Guaranteed by design. Not production tested.
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Silicon Oscillator with Low-Power Frequency Switching and Reset Output MAX7378
Typical Operating Characteristics
(VCC = VL = 5V, TA = +25C, unless otherwise noted.)
DUTY CYCLE vs. TEMPERATURE
MAX7378 toc01
DUTY CYCLE vs. TEMPERATURE
MAX7378 toc02
DUTY CYCLE vs. SUPPLY VOLTAGE
54 53 DUTY CYCLE (%) 52 51 50 49 48
MAX7378 toc03
55 54 53 DUTY CYCLE (%) 52 51 50 49 48 47 46 45 -55 -30 -5 20 45 70 95 120 TEMPERATURE (C) CLOCK = 32kHz
55 54 53 DUTY CYCLE (%) 52 51 50 49 48 47 46 45 -55 -30 -5 20 45 70 95 120 TEMPERATURE (C) CLOCK = 4MHz
55
47 46 45 4.3 4.6
CLOCK = 32kHz
4.9
5.2
5.5
SUPPLY VOLTAGE (V)
DUTY CYCLE vs. SUPPLY VOLTAGE
MAX7378 toc04
SUPPLY CURRENT vs. TEMPERATURE
MAX7378 toc05
SUPPLY CURRENT vs. TEMPERATURE
1.4 1.3 SUPPLY CURRENT (mA) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 CLOCK = 4 MHz
MAX7378 toc06
55 54 53 DUTY CYCLE (%) 52 51 50 49 48 47 46 45 4.3 4.6 4.9 5.2 CLOCK = 4MHz
14.0 13.5 SUPPLY CURRENT (A) 13.0 12.5 12.0 11.5 11.0 CLOCK = 32kHz 10.5 10.0
1.5
5.5
-55
-30
-5
20
45
70
95
120
-55
-30
-5
20
45
70
95
120
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
TEMPERATURE (C)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7378 toc07
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7378 toc08
FREQUENCY vs. SUPPLY VOLTAGE
34.5 34.0 FREQUENCY (kHz) 33.5 33.0 32.5 32.0 31.5 31.0 CLOCK = 32kHz
MAX7378 toc09
14 13 SUPPLY CURRENT (A) 12 11 10 9 CLOCK = 32kHz 8 4.3 4.6 4.9 5.2
1.5 1.4 1.3 SUPPLY CURRENT (mA) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 CLOCK = 4MHz 4.3 4.6 4.9 5.2
35.0
30.5 30.0 5.5 4.3 4.6 4.9 5.2 5.5
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
4
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Silicon Oscillator with Low-Power Frequency Switching and Reset Output MAX7378
Typical Operating Characteristics (continued)
(VCC = VL = 5V, TA = +25C, unless otherwise noted.)
FREQUENCY vs. SUPPLY VOLTAGE
MAX7378 toc10
FREQUENCY vs. TEMPERATURE
MAX7378 toc11
FREQUENCY vs. TEMPERATURE
4.08 4.06 FREQUENCY (MHz) 4.04 4.02 4.00 3.98 3.96
MAX7378 toc12
4.10 4.08 4.06 FREQUENCY (MHz) 4.04 4.02 4.00 3.98 3.96 3.94 3.92 3.90 4.3 4.6 4.9 5.2 CLOCK = 4MHz
33.0 32.9 32.8 FREQUENCY (kHz) 32.7 32.6 32.5 32.4 32.3 32.2 32.1 32.0 CLOCK = 32kHz
4.10
3.94 3.92 3.90
CLOCK = 4MHz
5.5
-55
-30
-5
20
45
70
95
120
-55
-30
-5
20
45
70
95
120
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
TEMPERATURE (C)
CLOCK OUTPUT WAVEFORM (CL = 10pF)
MAX7378 toc13
CLOCK OUTPUT WAVEFORM (CL = 50pF)
MAX7378 toc14
CLOCK OUTPUT WAVEFORM (CL = 100pF)
MAX7378 toc15
F = 4MHz, CL = 10pF 40ns/div
F = 4MHz, CL = 50pF 40ns/div
F = 4MHz, CL = 100pF 40ns/div
MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD
MAXIMUM TRANSIENT DURATION (s)
MAX7378 toc16
HIGH-SPEED TO LOW-SPEED TRANSITION
MAX7378 toc17
HIGH-SPEED TO LOW-SPEED TRANSITION (EXPANDED SCALE)
MAX7378 toc18
1000
RESET OCCURS ABOVE THE CURVE 100 CLOCK CLOCK
SPEED RESET = 4.29V 10 0 200 400 600 800 1000 20s/div RESET THRESHOLD OVERDRIVE (mV) 400s/div
SPEED
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Silicon Oscillator with Low-Power Frequency Switching and Reset Output MAX7378
Typical Operating Characteristics (continued)
(VCC = VL = 5V, TA = +25C, unless otherwise noted.)
LOW-SPEED TO HIGH-SPEED TRANSITION
MAX7378 toc19
LOW-SPEED TO HIGH-SPEED TRANSITION (EXPANDED SCALE)
MAX7378 toc20
CLOCK
CLOCK
SPEED
SPEED
20s/div
400s/div
Pin Description
PIN 1 2 3 4 5 6 7 8 NAME VCC VL SPEED RST CLOCK GND ENABLE N. C. FUNCTION Positive Supply Voltage. Bypass VCC to GND with a 0.1F capacitor. Output Supply Voltage. Connect VL to VCC. Bypass VL to GND with a 0.1F capacitor. Clock Speed-Select Input. Drive SPEED low to select the 32kHz fixed frequency. Drive SPEED high to select factory-trimmed frequency. Reset Output. See the RST Reset Output Options section for more details. Push-Pull Clock Output Ground Active-High Clock Enable Input. See the ENABLE Input section for more details. No Connect. No internal connection.
Detailed Description
The MAX7378 is a dual-speed clock generator with integrated reset for microcontrollers and UARTs in 3V, 3.3V, and 5V applications (Figure 1). The MAX7378 is a replacement for two crystal-oscillator modules, crystals, or ceramic resonators and a system-reset IC. The highspeed clock frequency is factory trimmed to specific values. A variety of popular standard frequencies are available (Table 2). The low-speed clock frequency is fixed at 32.768kHz (Figure 1). No external components are required for setting or adjusting the frequency.
Supply Voltage
The MAX7378 has been designed for use in systems with nominal supply voltages of 3V, 3.3V, or 5V and is specified for operation with supply voltages in the 2.7V to 5.5V range. See the Absolute Maximum Ratings section for limit values of power-supply and pin voltages.
Oscillator
The clock output is a push-pull configuration and is capable of driving a ground-connected 500 or a positive-supply connected 250 load to within 400mV of either supply rail. The clock output remains stable over the full operating voltage range and does not generate short output cycles when switching between high- and low-speed modes. A typical startup characteristic is shown in the Typical Operating Characteristics.
6
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Silicon Oscillator with Low-Power Frequency Switching and Reset Output
Applications Information
VCC VL
MAX7378
Interfacing to a Microcontroller Clock Input
The MAX7378 clock output is a push-pull, CMOS logic output that directly drives any P or C clock input. There are no impedance-matching issues when using the MAX7378. The MAX7378 is not sensitive to its position on the board and does not need to be placed right next to the P. Connect the MAX7378 VL pin and C (or other clock-input device) to the same supply voltage level. Refer to the C data sheet for clock-input compatibility with external clock signals. The MAX7378 requires no biasing components or load capacitance. When using the MAX7378 to retrofit a crystal oscillator, remove all biasing components from the oscillator input.
MAX7378 32kHz (LF OSCILLATOR)
POR
RST/RST
SPEED LOGIC ENABLE MUX CLOCK
RST Reset Output Options
600kHz TO 10MHz (HF OSCILLATOR)
Figure 1. Functional Diagram
The MAX7378 is available with three reset output stage options: push-pull with active-low output, push-pull with active-high output, and open drain with active-low output. The RST output is asserted when the monitored input (VCC) drops below the internal VTH- threshold and remains asserted for 100s after the monitored input exceeds the internal VTH+ threshold. The open-drain RST output requires an external pullup resistor.
ENABLE Input
The MAX7378 has an active-high enable input that controls the clock and reset outputs. The clock output is driven high when disabled. The reset asserts when disabled (low for active-low reset, high for active-high reset). Drive ENABLE low to disable the clock output on the next rising edge. Drive ENABLE high to activate the clock output.
Output Jitter
The MAX7378's jitter performance is given in the Electrical Characteristics table as a peak-to-peak value obtained by observing the output of the MAX7378 for 20s with a 500MHz oscilloscope. Jitter values are approximately proportional to the period of the output frequency of the device. Thus, a 4MHz part has approximately twice the jitter value of an 8MHz part. The jitter performance of clock sources degrades in the presence of mechanical and electrical interference. The MAX7378 is relatively immune to vibration, shock, and EMI influences, and thus provides a considerably more robust clock source than crystal or ceramic resonator-based oscillator circuits.
Clock-Speed Select Input
The MAX7378 uses logic input pin, SPEED, to set clock speed. Take this pin low to select slow clock speed (nominally 32.768kHz) or high to select full clock speed. The SPEED input may be strapped to VCC or to GND to select fast or slow clock speed, or connected to a logic output (such as a processor port) used to change clock speed on the fly. If the SPEED input is connected to a processor port that powers up in the input condition, connect a pullup or pulldown resistor to the SPEED input to set the clock to the preferred speed on power-up. The leakage current through the resistor into the SPEED input is very low, so a resistor value as high as 500k may be used.
Initial Power-Up and Operation
An intial power-up reset holds the reset output active for 100s (typ). However, the clock starts up within 30s (typ) at the frequency determined by the SPEED pin.
Power-Supply Brownout
The RST output is asserted whenever VCC drops below the specified threshold level. The action of VCC dropping below the reset threshold and then rising back above the threshold asserts RST and starts a normal
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7
Silicon Oscillator with Low-Power Frequency Switching and Reset Output
power-on reset cycle. The MAX7378 reset circuit features internal hysteresis that creates two trip points: one for rising supply voltage and one for falling supply voltage. The standard threshold values (see Table 1) are the trip points for rising supply voltage. The trip point for falling supply voltage is calculated by subtracting the hysteresis value from the rising supply trip point. The hysteresis prevents the reset output from oscillating (chattering) when VCC is near the voltage threshold. The reset circuit is immune to short transient VCC drops (see Maximum Transient Duration vs. Reset Threshold in the Typical Operating Characteristics).
MAX7378
Power-Supply Considerations
The MAX7378 operates with a 2.7V and 5.5V powersupply voltage. There are two power-supply pins, VCC and VL. V CC provides the main power input to the device and VL supplies the clock and reset output circuits. Good power-supply decoupling is needed to maintain the power-supply rejection performance of the MAX7378. Bypass both V CC and VL to GND with a 0.1F surface-mount ceramic capacitor. Mount the bypassing capacitors as close to the device as possible. If possible, mount the MAX7378 close to the C's decoupling capacitor so that additional decoupling is not required. A larger value bypass capacitor is recommended if the MAX7378 is to operate with a large capacitive load. Use a bypass capacitor value of at least 1000 times that of the output load capacitance. Note: VL must be equal to VCC.
Extended Temperature Operation
The MAX7378 was tested to +135C during product characterization and shown to function normally at this temperature (see the Typical Operating Characteristics). However, production test and qualification is only performed from -40C to +125C at this time. Contact the factory if operation outside this range is required.
Table 1. Standard Reset Threshold Levels
SUFFIX R RESET THRESHOLD (V) 2.57
Pin Configuration
TOP VIEW
VCC VL SPEED RST 1 2 3 4 8 N.C. ENABLE GND CLOCK
M 4.29 For all other reset threshold options, contact the factory.
MAX7378
7 6 5
Table 2. Standard Frequencies
SUFFIX MG OK QT QW RD RH STANDARD FREQUENCY (MHz) 1 1.8432 3.39545 3.6864 4 4.1943
MAX
TP 8 For all other frequency options, contact the factory.
8
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Silicon Oscillator with Low-Power Frequency Switching and Reset Output MAX7378
Table 3. Standard Part Numbers
PART MAX7378CRMG MAX7378CROK MAX7378CRQT MAX7378CRQW MAX7378CRRD MAX7378CRRH MAX7378CRTP MAX7378CMMG MAX7378CMOK MAX7378CMQT MAX7378CMQW MAX7378CMRD MAX7378CMRH MAX7378CMTP PIN-PACKAGE 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX 8 MAX RESET OUTPUT TYPE Open drain Open drain Open drain Open drain Open drain Open drain Open drain Open drain Open drain Open drain Open drain Open drain Open drain Open drain RESET THRESHOLD (V) 2.57 2.57 2.57 2.57 2.57 2.57 2.57 4.29 4.29 4.29 4.29 4.29 4.29 4.29 FREQUENCY (MHZ) 1 1.8432 3.39545 3.6864 4 4.1943 8 1 1.8432 3.39545 3.6864 4 4.1943 8
Chip Information
TRANSISTOR COUNT: 2027 PROCESS: BiCMOS
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9
Silicon Oscillator with Low-Power Frequency Switching and Reset Output MAX7378
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
4X S
8
8
INCHES DIM A A1 A2 b MIN 0.002 0.030 MAX 0.043 0.006 0.037
MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95
y 0.500.1
E
H
0.60.1
c D e E H L
1
1
0.60.1
S
D
BOTTOM VIEW
0.014 0.010 0.007 0.005 0.120 0.116 0.0256 BSC 0.120 0.116 0.198 0.188 0.026 0.016 6 0 0.0207 BSC
0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.5250 BSC
TOP VIEW
A2
A1
A
c e b L
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL DOCUMENT CONTROL NO. REV.
21-0036
1 1
J
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.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
8LUMAXD.EPS

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