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 microcon-
trollers and UARTs in 3V, 3.3V, and 5V applications.
The MAX7381 is an integrated oscillator, supplied at spe-
cific 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 compo-
nents are required for setting or adjusting the frequency.
Unlike typical crystal and ceramic resonator oscillator cir-
cuits, the MAX7381 is resistant to vibration and EMI. The
high output-drive current and absence of high-imped-
ance nodes make the oscillator invulnerable to dirty or
humid operating conditions. With a wide operating tem-
perature range as standard, the oscillator is a good
choice for demanding appliance and automotive environ-
ments. 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.
♦
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
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
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
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
µC
GND
OSC2
Selector Guide appears at end of data sheet.
________________________________________________________________
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.
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 (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
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, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at V+ = 5V, T
A
= +25°C, unless otherwise
noted.) (Note 1)
PARAMETER
Operating Supply Voltage
Operating Supply Current
SYMBOL
V+
I+
MAX7381AXR126
MAX7381AXR166
V+
≥
2.7V, I
SOURCE
= 2.5mA
Output High Voltage
V
OH
V+
≥
4.5V, I
SOURCE
= 9mA
Output Low Voltage
On-Resistance
V
OL
V+
≥
2.7V, I
SINK
= 10mA
V+
≥
4.5V, I
SINK
= 20mA
V
IN
= 3V (typ value at T
A
= +25°C)
V
IN
= 5V (typ value at T
A
= +25°C)
V+ = 5.0V,
T
A
= +25°C
V+ = 2.7V to 5.5V,
T
A
= +25°C
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
%
ps
P
-
P
ns
ns
µs
V
Ω
CONDITIONS
MIN
2.7
3.7
4.8
TYP
MAX
5.5
4.75
6.50
UNITS
V
mA
Initial CLOCK Frequency
(Note 2)
f
CLOCK
CLOCK Frequency Temperature
Sensitivity
Duty Cycle
Output Jitter
Output Rise Time
Output Fall Time
Startup Time
t
R
t
F
T
A
= -40°C to +125°C, (Note 3)
(Note 3)
Observation for 20s using a 12GHz
oscilloscope (MAX7381AXR166)
Note 1:
All parameters tested at T
A
= +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.
2
_______________________________________________________________________________________
3-Pin Silicon Oscillator
MAX7381
Typical Operating Characteristics
(V+ = 5V, C
L
= 10pF, 16MHz output, T
A
= +25°C, 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 C
L
= 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)
_______________________________________________________________________________________
3
3-Pin Silicon Oscillator
MAX7381
Typical Operating Characteristics (continued)
(V+ = 5V, C
L
= 10pF, 16MHz output, T
A
= +25°C, unless otherwise noted.)
CLOCK OUTPUT WAVEFORM
WITH C
L
= 50pF
MAX7381 toc10
CLOCK OUTPUT WAVEFORM
WITH C
L
= 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 oscilla-
tor, supplied at specific frequencies just like crystals
and resonators. A variety of popular standard frequen-
cies 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 0.1µF surface-mount
ceramic capacitor.
Clock Output. CLOCK is a push-
pull 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 guar-
anteed. 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.
are approximately proportional to the period of the out-
put 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 ceramic-
resonator-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 imped-
ance-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
4
_______________________________________________________________________________________
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 +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.
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 perfor-
mance 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 pos-
sible, 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 out-
put-load capacitance.
Pin Configuration
TOP VIEW
V+ 1
MAX7381
CLOCK 2
3 GND
SC70
_______________________________________________________________________________________
5
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