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19-3474; Rev 0; 10/04
Silicon Oscillator with Low-Power Frequency Switching
General Description
The MAX7377 dual-speed silicon oscillator with reset is a replacement for ceramic resonators, crystals, crystal oscillator modules, and discrete reset circuits. The device provides the primary and secondary clock source for microcontrollers in 3V, 3.3V, and 5V applications. The MAX7377 features a factory-programmed high-speed oscillator, a 32.768kHz oscillator, and a clock selector input. The clock output can be switched at any time between the high-speed clock and the 32.768kHz clock for low-power operation. Switchover is synchronized internally to provide glitch-free clock switching. Unlike typical crystal and ceramic resonator oscillator circuits, the MAX7377 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 MAX7377 is a good choice for demanding home appliance, industrial, and automotive environments. The MAX7377 is available in factory-programmed frequencies from 32.768kHz to 10MHz. See Table 1 for standard frequencies and contact the factory for custom frequencies. The MAX7377 is available in a 5-pin SOT23 package. Refer to the MAX7383 data sheet for frequencies 10MHz. The MAX7377 standard operating temperature range is -40C to +125C. See the Applications Information section for the extended operating temperature range. 2.7V to 5.5V Operation Accurate High-Speed 600kHz to 10MHz Oscillator Accurate Low-Speed 32kHz Oscillator Glitch-Free Switch Between High Speed and Low Speed at Any Time 10mA Clock-Output Drive Capability 2% Initial Accuracy 50ppm/C Temperature Coefficient 50% Duty Cycle 5ns Output Rise and Fall Time Low Jitter: 160ps(P-P) at 8MHz (No PLL) 3mA Fast-Mode Operating Current (8MHz) 13A Slow-Mode Operating Current (32kHz) -40C to +125C Temperature Range
Features
MAX7377
Ordering Information
PART MAX7377AX_ _-T TEMP RANGE -40C to +125C PIN-PACKAGE 5 SOT23-5
The first two letters are AX. See Table 1 at the end of the data sheet for the two-letter code.
Applications
White Goods Handheld Products Automotive Portable Equipment Consumer Products Microcontroller Systems Appliances and Controls
TOP VIEW
CLOCK 1 5 E.C.
Pin Configuration
GND 2
MAX7377
SPEED 3
4
VCC
Typical Application Circuit appears at end of data sheet.
SOT23
________________________________________________________________ Maxim Integrated Products
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Silicon Oscillator with Low-Power Frequency Switching MAX7377
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) 5-Pin SOT23 (derate 7.1mW/C above +70C) ...................571mW (U5 - 2) 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, TA = -40C to +125C, unless otherwise noted. Typical values are at VCC = 5V and TA = +25C.) (Note 1)
PARAMETER Operating Supply Voltage Operating Supply Current LOGIC INPUT (SPEED) Input High Voltage Input Low Voltage Input Current CLOCK OUTPUT VCC = 4.5V, ISOURCE = 9mA Output High Voltage VOH VCC = 2.7V, ISOURCE = 2.5mA Output Low Voltage Initial Fast CLOCK Frequency Accuracy VOL fFCLOCK VCC = 4.5V, ISINK = 20mA VCC = 2.7V, ISINK = 10mA VCC = 5V, TA = +25C (Note 2) VCC = 2.7V to 5.5V, TA = +25C -2 -4 VCC - 0.4 V VCC - 0.4 0.4 0.4 +2 +4 V % VIH VIL IIN 0.7 x VCC 0.3 x VCC 2 V V A SYMBOL VCC ICC fCLOCK = 8MHz, no load fCLOCK = 32.768kHz, no load CONDITIONS MIN 2.7 3 13 TYP MAX 5.5 5 25 UNITS V mA A
2
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Silicon Oscillator with Low-Power Frequency Switching
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 2.7V to 5.5V, TA = -40C to +125C, unless otherwise noted. Typical values are at VCC = 5V and TA = +25C.) (Note 1)
PARAMETER Fast CLOCK Frequency Temperature Sensitivity Initial Slow CLOCK Frequency Accuracy Slow CLOCK Frequency Temperature Sensitivity CLOCK Output Duty Cycle CLOCK Output Jitter CLOCK Output Rise Time CLOCK Output Fall Time Startup Delay Output Undervoltage Lockout Output Undervoltage Lockout Hysteresis UVLO VTHYS tR tF Observation of 8MHz output for 20s using a 500MHz oscilloscope 10% to 90% 90% to 10% VCC rising from 0 to 5V in 1s VCC rising TA = +25C TA = -40C to +125C 2.15 2.05 45 fSCLOCK SYMBOL (Note 3) VCC = 5V, TA = +25C (Note 2) VCC = 2.7V to 5.5V, TA = +25C (Note 3) 43 32.440 31.785 50 50 160 5 5 100 2.2 2.25 2.35 CONDITIONS MIN TYP 50 32.768 MAX 325 33.096 33.751 325 57 UNITS ppm/oC kHz ppm/oC % psP-P ns ns s V mV
MAX7377
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 Table 1. Note 3: Guaranteed by design. Not production tested.
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Silicon Oscillator with Low-Power Frequency Switching MAX7377
Typical Operating Characteristics
(VCC = 5V, TA = +25C, unless otherwise noted.)
DUTY CYCLE vs. TEMPERATURE
MAX7377 toc01
DUTY CYCLE vs. TEMPERATURE
MAX7377 toc02
DUTY CYCLE vs. SUPPLY VOLTAGE
54 53 DUTY CYCLE (%) 52 51 50 49 48 47 46 45 CLOCK = 32kHz
MAX7377 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
CLOCK = 4MHz
-55
-30
-5
20
45
70
95
120
4.3
4.6
4.9
5.2
5.5
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
DUTY CYCLE vs. SUPPLY VOLTAGE
MAX7377 toc04
SUPPLY CURRENT vs. TEMPERATURE
MAX7377 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 = 4MHz
MAX7377 toc06
55 54 53 DUTY CYCLE (%) 52 51 50 49 48 47 46 45
CLOCK = 4MHz
14.0 CLOCK = 32kHz 13.5 SUPPLY CURRENT (A) 13.0 12.5 12.0 11.5 11.0 10.5 10.0
1.5
4.3
4.6
4.9
5.2
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
MAX7377 toc07
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7377 toc08
FREQUENCY vs. SUPPLY VOLTAGE
34.5 34.0 FREQUENCY (kHz) 33.5 33.0 32.5 32.0 31.5 31.0 30.5 30.0 CLOCK = 32kHz
MAX7377 toc09
30 CLOCK = 32kHz 25 SUPPLY CURRENT (A) 20 15 10 5 0 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
35.0
CLOCK = 4MHz
5.5
4.3
4.6
4.9
5.2
5.5
4.3
4.6
4.9
5.2
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
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Silicon Oscillator with Low-Power Frequency Switching MAX7377
Typical Operating Characteristics (continued)
(VCC = 5V, TA = +25C, unless otherwise noted.)
FREQUENCY vs. SUPPLY VOLTAGE
MAX7377 toc10
FREQUENCY vs. TEMPERATURE
MAX7377 toc11
FREQUENCY vs. TEMPERATURE
4.08 4.06 FREQUENCY (MHz) 4.04 4.02 4.00 3.98 3.96 3.94 3.92 3.90 CLOCK = 4MHz
MAX7377 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
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
4.3
4.6
4.9
5.2
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)
MAX7377 toc13
CLOCK OUTPUT WAVEFORM (CL = 50pF)
MAX7377 toc14
CLOCK OUTPUT WAVEFORM (CL = 100pF)
MAX7377 toc15
CLOCK
CLOCK
CLOCK
f = 4MHz, CL = 10pF 40ns/div
f = 4MHz, CL = 50pF 40ns/div
f = 4MHz, CL = 100pF 40ns/div
HIGH-SPEED TO LOW-SPEED TRANSITION
MAX7377 toc16
HIGH-SPEED TO LOW-SPEED TRANSITION (EXPANDED SCALE)
MAX7377 toc17
20s/div
400ns/div
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Silicon Oscillator with Low-Power Frequency Switching MAX7377
Typical Operating Characteristics (continued)
(VCC = 5V, TA = +25C, unless otherwise noted.)
LOW-SPEED TO HIGH-SPEED TRANSITION
MAX7377 toc18
LOW-SPEED TO HIGH-SPEED TRANSISTION (EXPANDED SCALE)
MAX7377 toc19
CLOCK
SPEED
20s/div
400ns/div
Pin Description
PIN 1 2 3 4 5 NAME CLOCK GND SPEED VCC E.C. Push-Pull Clock Output Ground Clock-Speed Select Input. Drive SPEED low to select the 32kHz fixed frequency. Drive SPEED high to select factory-trimmed frequency. Positive Supply Voltage. Bypass VCC to GND with a 0.1F capacitor. Must be Externally Connected to VCC FUNCTION
Detailed Description
The MAX7377 is a dual-speed clock generator for microcontrollers (Cs) and UARTs in 3V, 3.3V, and 5V applications. (Figure 1). The MAX7377 is a replacement for two crystal oscillator modules, crystals, or ceramic resonators. The high-speed clock frequency is factory trimmed to specific values. A variety of popular standard frequencies are available. The low-speed clock frequency is fixed at 32.768kHz (Table 1). No external components are required for setting or adjusting the frequency.
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.
Clock-Speed Select Input
The MAX7377 uses a 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 can 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
Supply Voltage
The MAX7377 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.
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Silicon Oscillator with Low-Power Frequency Switching
VCC
Output Jitter
The MAX7377's jitter performance is given in the Electrical Characteristics table as a peak-to-peak value obtained by observing the output of the MAX7377 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 MAX7377 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.
MAX7377
MAX7377
600kHz TO 10MHz (HF OSCILLATOR)
POR
SPEED LOGIC MUX CLOCK
Initial Power-Up and Operation
32kHz (LF OSCILLATOR)
An internal power-up reset disables the oscillator until VCC has risen above 2.2V. The clock then starts up within 30s (typ) at the frequency determined by the SPEED pin.
Extended Temperature Operation
The MAX7377 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.
Figure 1. Functional Diagram
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.
Power-Supply Considerations
The MAX7377 operates with a 2.7V and 5.5V powersupply voltage. Good power-supply decoupling is needed to maintain the power-supply rejection performance of the MAX7377. Bypass VCC to GND with a 0.1F surface-mount ceramic capacitor. Mount the bypass capacitor as close to the device as possible. If possible, mount the MAX7377 close to the microcontroller's decoupling capacitor so that additional decoupling is not required. A larger value bypass capacitor is recommended if the MAX7377 is to operate with a large capacitive load. Use a bypass capacitor value of at least 1000 times that of the output load capacitance.
Applications Information
Interfacing to a Microcontroller Clock Input
The MAX7377 clock output is a push-pull, CMOS, logic output that directly drives any microprocessor (P) or C clock input. There are no impedance-matching issues when using the MAX7377. The MAX7377 is not sensitive to its position on the board and does not need to be placed right next to the P. Refer to the microcontroller data sheet for clock-input compatibility with external clock signals. The MAX7377 requires no biasing components or load capacitance. When using the MAX7377 to retrofit a crystal oscillator, remove all biasing components from the oscillator input.
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Silicon Oscillator with Low-Power Frequency Switching MAX7377
Typical Application Circuit
SUPPLY VOLTAGE
Table 1. Standard Frequencies
SUFFIX MG OK QT QW RD RH TP STANDARD FREQUENCY (MHz) 1 1.8432 3.39545 3.6864 4 4.1943 8
VCC E.C.
OSC1 CLOCK OSC2 C
For all other reset threshold options, contact factory.
MAX7377
SPEED
I/O PORT
Table 2. Standard Part Numbers
PART MAX7377AXMG MAX7377AXOK MAX7377AXQT MAX7377AXQW MAX7377AXRD MAX7377AXRH MAX7377AXTP PIN-PACKAGE 5 SOT23 5 SOT23 5 SOT23 5 SOT23 5 SOT23 5 SOT23 5 SOT23 FREQUENCY (Hz) 1M 1.8432M 3.39545M 3.6864M 4M 4.1943M 8M TOP MARK AENE AEND AEMY AEMZ AENA AENB AENC
Chip Information
TRANSISTOR COUNT: 2027 PROCESS: BiCMOS
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Silicon Oscillator with Low-Power Frequency Switching
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.)
SOT-23 5L .EPS
MAX7377
PACKAGE OUTLINE, SOT-23, 5L
21-0057
E
1
1
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 _____________________ 9 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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