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19-3697; Rev 0; 4/05
3-Pin Silicon Oscillator
General Description
The MAX7381 is a silicon oscillator intended as a low-cost improvement to ceramic resonators, crystals, and crystal oscillator modules as the clock source for microcontrollers and UARTs in 3V, 3.3V, and 5V applications. The MAX7381 is an integrated oscillator, supplied at specific frequencies, just like crystals and resonators, and with a rail-to-rail, 50%, duty-cycle square-wave output. The oscillator frequency is generated directly without the use of a phase-locked loop (PLL). No additional components are required for setting or adjusting the frequency. Unlike typical crystal and ceramic resonator oscillator circuits, the MAX7381 is resistant to vibration and EMI. The high output-drive current and absence of high-impedance nodes make the oscillator invulnerable to dirty or humid operating conditions. With a wide operating temperature range as standard, the oscillator is a good choice for demanding appliance and automotive environments. The MAX7381 is available with frequencies in the 10MHz to 16MHz range. The MAX7381 is offered in a space-saving 3-pin SC70 package. All ICs are guaranteed to operate over the -55C to +135C temperature range and specified from the -40C to +125C temperature range. 2.7V to 5.5V Operation Factory-Trimmed Oscillator (10MHz to 16MHz) No External Components Required 10mA Output-Drive Current 2% Initial Accuracy 100ppm/C Temperature Drift Fast Startup Time: 5s 40% to 60% Maximum Duty Cycle 5ns Output Rise/Fall Time Very-Low-EMI Susceptibility (No High-Impedance Nodes) No PLL Low Jitter: 180psP-P at 16MHz -40C to +125C Temperature Range
Features
MAX7381
Applications
White Goods Automotive Appliances and Controls Handheld Products Portable Equipment Microcontroller Systems
PART MAX7381AXR106-T MAX7381AXR126-T MAX7381AXR146-T MAX7381AXR166-T
Ordering Information
TEMP RANGE -40C to +125C -40C to +125C -40C to +125C -40C to +125C PIN-PACKAGE 3 SC70-3 3 SC70-3 3 SC70-3 3 SC70-3
Typical Operating Circuit
2.7V TO 5.5V
The MAX7381 is available in factory-set frequencies from 10MHz to 16MHz. There are four standard versions 10MHz, 12MHz, 14MHz, and 16MHz, shown in the Selector Guide) with a required order increment of 2.5K. Nonstandard frequencies are also available with a required order increment of 10K. For nonstandard versions, contact factory for availability and ordering information. All versions are available in tape and reel only. Refer to the MAX7375 data sheet for output frequencies below 10MHz.
V+ CLOCK
OSC1
MAX7381
C GND
OSC2
Selector Guide appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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3-Pin Silicon Oscillator MAX7381
ABSOLUTE MAXIMUM RATINGS
V+ to GND .............................................................-0.3V to +6.0V CLK to GND..................................................-0.3V to (V+ + 0.3V) CLK Current .....................................................................50mA Continuous Power Dissipation (TA = + 70C) 3-Pin SC70 (derate 2.9mW/C over +70C) ..............235.3mW Functional Temperature Range .........................-55C to +135C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C 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
(V+ = 2.7V to 5.5V, TA = -40C to +125C, unless otherwise noted. Typical values are at V+ = 5V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Operating Supply Voltage Operating Supply Current SYMBOL V+ I+ MAX7381AXR126 MAX7381AXR166 V+ 2.7V, ISOURCE = 2.5mA Output High Voltage VOH V+ 4.5V, ISOURCE = 9mA Output Low Voltage On-Resistance VOL V+ 2.7V, ISINK = 10mA V+ 4.5V, ISINK = 20mA VIN = 3V (typ value at TA = +25C) VIN = 5V (typ value at TA = +25C) V+ = 5.0V, TA = +25C V+ = 2.7V to 5.5V, TA = +25C MAX7381AXR_ _ _ MAX7381AXR_ _ _ -2% -5% -350 40 100 50 180 5 5 5 0.11 0.095 V+ 0.4 V V+ 0.4 0.4 0.4 0.17 0.15 +2% MHz +3% +300 60 ppm/C % psP-P ns ns s V CONDITIONS MIN 2.7 3.7 4.8 TYP MAX 5.5 4.75 6.50 UNITS V mA
Initial CLOCK Frequency (Note 2)
fCLOCK
CLOCK Frequency Temperature Sensitivity Duty Cycle Output Jitter Output Rise Time Output Fall Time Startup Time tR tF
TA = -40C to +125C, (Note 3) (Note 3) Observation for 20s using a 12GHz oscilloscope (MAX7381AXR166)
Note 1: All parameters tested at TA = +25C. Specifications over temperature are guaranteed by design and characterization. Note 2: Typical frequencies are nominal values. Note 3: Guaranteed by design and characterization. Not production tested.
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3-Pin Silicon Oscillator MAX7381
Typical Operating Characteristics
(V+ = 5V, CL = 10pF, 16MHz output, TA = +25C, unless otherwise noted.)
DUTY CYCLE vs. TEMPERATURE
MAX7381 toc01
DUTY CYCLE vs. SUPPLY VOLTAGE
MAX7381 toc02
SUPPLY CURRENT vs. TEMPERATURE
V+ = 5V 5 SUPPLY CURRENT (mA) 4 3 2 1 0 V+ = 2.7V V+ = 3.3V
MAX7381 toc03 MAX7381 toc09 MAX7381 toc06
55 54 53 DUTY CYCLE (%) 52 51 50 49 48 47 46 45
55
6
53 DUTY CYCLE (%)
51
49
47
45 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7381 toc04
FREQUENCY vs. SUPPLY VOLTAGE
MAX7381 toc05
FREQUENCY vs. TEMPERATURE
1.035 1.025 NORMALIZED FREQUENCY 1.015 1.005 0.995 0.985 0.975
6 5 SUPPLY CURRENT (mA) 4 3 2 1 0 2.5 3.0 3.5 4.0 4.5 5.0
1.010 1.005 NORMALIZED FREQUENCY 1.000 0.995 0.990 0.985 0.980
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY CURRENT vs. FREQUENCY
MAX7381 toc07
SETTLING TIME FROM START
MAX7381 toc08
CLOCK OUTPUT WAVEFORM WITH CL = 10pF
6 5 SUPPLY CURRENT (mA) 4 3 2 1 V+ = 5V 0 10 11 12 13 14 15
CLOCK 2V/div
CLOCK 1V/div
V+ 2V/div V+ = 3.3V 16 20ns/div V+ = 3.3V
100ns/div
FREQUENCY (MHz)
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3-Pin Silicon Oscillator MAX7381
Typical Operating Characteristics (continued)
(V+ = 5V, CL = 10pF, 16MHz output, TA = +25C, unless otherwise noted.)
CLOCK OUTPUT WAVEFORM WITH CL = 50pF
MAX7381 toc10
CLOCK OUTPUT WAVEFORM WITH CL = 100pF
MAX7381 toc11
CLOCK 1V/div V+ = 3.3V V+ = 3.3V
CLOCK 1V/div
20ns/div
20ns/div
Detailed Description
The MAX7381 is a replacement for ceramic resonators, crystals, and crystal-oscillator modules as the clock source for microcontrollers and UARTs in 3V, 3.3V, and 5V applications. The MAX7381 is an integrated oscillator, supplied at specific frequencies just like crystals and resonators. A variety of popular standard frequencies are available. No external components are required for setting or adjusting the frequency.
PIN 1 NAME V+
Pin Description
FUNCTION Positive Supply Voltage. Bypass V+ to GND with a 0.1F surface-mount ceramic capacitor. Clock Output. CLOCK is a pushpull output. Ground
2 3
CLOCK GND
Supply Voltages
The MAX7381 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. Operation outside this range is not guaranteed. See the Absolute Maximum Ratings for limit values of power-supply and pin voltages.
are approximately proportional to the period of the output frequency of the device. The jitter performance of all clock sources degrades in the presence of mechanical and electrical interference. The MAX7381 is relatively immune to vibration, shock, and EMI influences, and thus provides a considerably more robust clock source than crystal- or ceramicresonator-based oscillator circuits.
Oscillator
The clock output is a push-pull configuration and is capable of driving a ground-connected 1k load or a positive-supply-connected 500 load to within 400mV of either supply rail. The clock output remains stable over the full operating voltage range. A typical startup characteristic is shown in the Typical Operating Characteristics section.
Applications Information
Interfacing to a Microcontroller Clock Input
The MAX7381 clock output is a push-pull, CMOS, logic output, which directly drives any microprocessor (P) or microcontroller (C) clock input. There are no impedance-matching issues when using the MAX7381. Operate the MAX7381 and microcontroller (or other clock-input device) from the same supply voltage. Refer to the microcontroller data sheet for clock-input compatibility with external clock signals.
Output Jitter
The MAX7381's jitter performance is given in the Electrical Characteristics table as a peak-to-peak value obtained by observing the output of the MAX7381 for 20s with a 500MHz oscilloscope. Jitter measurements
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3-Pin Silicon Oscillator
The MAX7381 requires no biasing components or load capacitance. When using the MAX7381 to retrofit a crystal oscillator, remove all biasing components from the oscillator input.
MAX7381
Chip Information
PROCESS: BiCMOS
Startup Performance
The MAX7381 oscillator output stabilizes within a few cycles of operation after V+ rises to a sufficient voltage to start the oscillator, typically 1.65V at +25C. Use a reset or similar voltage-detection circuit to disable devices connected to the MAX7381 until 20s after the voltage on V+ has risen above 2.7V.
Selector Guide
PART MAX7381AXR106 MAX7381AXR126 MAX7381AXR146 MAX7381AXR166 FREQUENCY (MHz) 10 12 14 16 TOP MARK APE APG ARC APH
Power-Supply Considerations
The MAX7381 operates with power-supply voltages in the 2.7V to 5.5V range. Power-supply decoupling is needed to maintain the power-supply rejection performance of the MAX7381. Use a 0.1F surface-mount ceramic capacitor connected between V+ and GND and mounted as close to the device as possible. If possible, mount the MAX7381 close to the microcontroller's decoupling capacitor so that additional decoupling is not required. A larger value bypass capacitor is recommended if the MAX7381 is driving a large capacitive load. Use a bypass capacitor value of at least 1000 times the output-load capacitance.
Pin Configuration
TOP VIEW
V+ 1
MAX7381
CLOCK 2
3 GND
SC70
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3-Pin Silicon Oscillator MAX7381
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.)
PACKAGE OUTLINE, 3L SC70
21-0075
C
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 _____________________ 6 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
SC70, 3L.EPS

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