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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
-55°C to +135°C temperature range and specified from
the -40°C to +125°C temperature range.
Applications
White Goods
Automotive
Appliances and Controls
Handheld Products
Portable Equipment
Microcontroller Systems
Features
♦ 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: 5µs
♦ 40% to 60% Maximum Duty Cycle
♦ 5ns Output Rise/Fall Time
♦ Very-Low-EMI Susceptibility (No High-Impedance
Nodes)
♦ No PLL
♦ Low Jitter: 180ps
P-P
at 16MHz
♦ -40°C to +125°C Temperature Range
MAX7381
3-Pin Silicon Oscillator
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-3697; Rev 0; 4/05
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.
PART TEMP RANGE
PIN-PACKAGE
MAX7381AXR106-T -40°C to +125°C 3 SC70-3
MAX7381AXR126-T -40°C to +125°C 3 SC70-3
MAX7381AXR146-T -40°C to +125°C 3 SC70-3
MAX7381AXR166-T -40°C to +125°C 3 SC70-3
Typical Operating Circuit
Selector Guide appears at end of data sheet.
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.
2.7V TO 5.5V
V+
CLOCK
OSC1
MAX7381
GND
µC
OSC2
MAX7381
3-Pin Silicon Oscillator
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
V+ to GND .............................................................-0.3V to +6.0V
CLK to GND..................................................-0.3V to (V+ + 0.3V)
CLK Current .....................................................................±50mA
Continuous Power Dissipation (T
A
= + 70°C)
3-Pin SC70 (derate 2.9mW/°C over +70°C)..............235.3mW
Functional Temperature Range .........................-55°C to +135°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(V+ = 2.7V to 5.5V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at V+ = 5V, TA= +25°C, unless otherwise
noted.) (Note 1)
PARAMETER
CONDITIONS
UNITS
Operating Supply Voltage V+ 2.7 5.5 V
MAX7381AXR126 3.7
Operating Supply Current I+
MAX7381AXR166 4.8
mA
V+ ≥ 2.7V, I
SOURCE
= 2.5mA
V+ -
0.4
Output High Voltage V
OH
V+ ≥ 4.5V, I
SOURCE
= 9mA
V+ -
0.4
V
V+ ≥ 2.7V, I
SINK
= 10mA 0.4
Output Low Voltage V
OL
V+ ≥ 4.5V, I
SINK
= 20mA 0.4
V
VIN = 3V (typ value at TA = +25°C)
On-Resistance
V
IN
= 5V (typ value at TA = +25°C)
Ω
V+ = 5.0V,
T
A
= +25°C
Initial CLOCK Frequency
(Note 2)
f
CLOCK
V+ = 2.7V to 5.5V,
T
A
= +25°C
MHz
CLOCK Frequency Temperature
Sensitivity
T
A
= - 40°C to + 125°C , (Note 3)
ppm/°C
Duty Cycle (Note 3) 40 50 60 %
Output Jitter
Observation for 20s using a 12GHz
oscilloscope (MAX7381AXR166)
psP-
P
Output Rise Time t
R
5ns
Output Fall Time t
F
5ns
Startup Time 5µs
Note 1: All parameters tested at TA= +25°C. 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.
SYMBOL
MIN TYP MAX
4.75
6.50
0.11 0.17
0.095 0.15
MAX7381AXR_ _ _ -2% +2%
MAX7381AXR_ _ _ -5% +3%
-350 100 +300
180
MAX7381
3-Pin Silicon Oscillator
_______________________________________________________________________________________ 3
DUTY CYCLE vs. TEMPERATURE
MAX7381 toc01
TEMPERATURE (°C)
DUTY CYCLE (%)
1109565 80-10 5 20 35 50-25
46
47
48
49
50
51
52
53
54
55
45
-40 125
DUTY CYCLE vs. SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
5.0
4.54.03.53.0
47
49
51
53
55
45
2.5 5.5
MAX7381 toc02
DUTY CYCLE (%)
SUPPLY CURRENT vs. TEMPERATURE
MAX7381 toc03
SUPPLY CURRENT (mA)
1
2
3
4
5
6
0
TEMPERATURE (
°C)
1109565 80-10 5 20 35 50-25-40 125
V+ = 5V
V+ = 3.3V
V+ = 2.7V
SUPPLY VOLTAGE (V)
5.0
4.54.03.53.02.5 5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7381 toc04
SUPPLY CURRENT (mA)
1
2
3
4
5
6
0
SUPPLY VOLTAGE (V)
5.0
4.54.03.53.02.5 5.5
FREQUENCY vs. SUPPLY VOLTAGE
MAX7381 toc05
NORMALIZED FREQUENCY
0.985
0.990
0.995
1.000
1.005
1.010
0.980
FREQUENCY vs. TEMPERATURE
MAX7381 toc06
NORMALIZED FREQUENCY
0.985
0.995
1.005
1.015
1.025
1.035
0.975
TEMPERATURE (
°C)
1109565 80-10 5 20 35 50-25-40 125
FREQUENCY (MHz)
15
1413121110 16
SUPPLY CURRENT vs. FREQUENCY
MAX7381 toc07
SUPPLY CURRENT (mA)
1
2
3
4
5
6
0
V+ = 5V
Typical Operating Characteristics
(V+ = 5V, CL= 10pF, 16MHz output, TA= +25°C, unless otherwise noted.)
SETTLING TIME FROM START
MAX7381 toc08
CLOCK
2V/div
V+
2V/div
100ns/div
V+ = 3.3V
CLOCK OUTPUT WAVEFORM
WITH C
L
= 10pF
MAX7381 toc09
CLOCK
1V/div
20ns/div
V+ = 3.3V
MAX7381
3-Pin Silicon Oscillator
4 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V+ = 5V, CL= 10pF, 16MHz output, TA= +25°C, unless otherwise noted.)
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.
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.
Oscillator
The clock output is a push-pull configuration and is
capable of driving a ground-connected 1kΩ load or a
positive-supply-connected 500Ω 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.
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
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.
Applications Information
Interfacing to a Microcontroller
Clock Input
The MAX7381 clock output is a push-pull, CMOS, logic
output, which directly drives any microprocessor (µP)
or microcontroller (µC) 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.
Pin Description
PIN NAME FUNCTION
1V+
Positive Supply Voltage. Bypass V+
to GND with a 0.1µF surface-mount
ceramic capacitor.
2
Clock Output. CLOCK is a pushpull output.
3 GND Ground
CLOCK OUTPUT WAVEFORM
WITH C
= 50pF
L
MAX7381 toc10
V+ = 3.3V
20ns/div
CLOCK
1V/div
CLOCK OUTPUT WAVEFORM
WITH C
= 100pF
L
20ns/div
MAX7381 toc11
V+ = 3.3V
CLOCK
CLOCK
1V/div
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.
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 +25°C. Use a
reset or similar voltage-detection circuit to disable
devices connected to the MAX7381 until 20µs after the
voltage on V+ has risen above 2.7V.
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 0.1µF 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.
MAX7381
3-Pin Silicon Oscillator
_______________________________________________________________________________________ 5
PART
MAX7381AXR106 10 APE
MAX7381AXR126 12 APG
MAX7381AXR146 14 ARC
MAX7381AXR166 16 APH
Selector Guide
Chip Information
PROCESS: BiCMOS
CLOCK
1
3
GND
V+
MAX7381
SC70
TOP VIEW
2
Pin Configuration
FREQUENCY (MHz) TOP MARK
MAX7381
3-Pin Silicon Oscillator
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
© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
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
.)
SC70, 3L.EPS
PACKAGE OUTLINE, 3L SC70
21-0075
1
1
C
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