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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 -40°C to +125°C. See the Applications
Information section for the extended operating temperature range.
Applications
White Goods Handheld Products
Automotive Portable Equipment
Consumer Products Microcontroller Systems
Appliances and Controls
Features
♦ 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)
♦ 13µA Slow-Mode Operating Current (32kHz)
♦ -40°C to +125°C Temperature Range
MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
________________________________________________________________ Maxim Integrated Products 1
Pin Configuration
Ordering Information
19-3474; Rev 0; 10/04
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.
The first two letters are AX. See Table 1 at the end of the data
sheet for the two-letter code.
PART TEMP RANGE PIN-PACKAGE
M AX7377AX _ _- T -40°C to +125°C5 SOT23-5
Typical Application Circuit appears at end of data sheet.
TOP VIEW
15E.C.CLOCK
MAX7377
2
GND
SPEED
34
SOT23
V
CC
Page 2
MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC= 2.7V to 5.5V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at VCC= 5V and TA = +25°C.) (Note 1)
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.
VCCto GND .............................................................-0.3V to +6V
All Other Pins to GND ................................-0.3V to (V
CC
+ 0.3V)
CLOCK Current ................................................................±10mA
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SOT23
(derate 7.1mW/°C above +70°C) ...................571mW (U5 - 2)
Operating Temperature Range .........................-40°C to +135°C
Junction Temperature .....................................................+150°C
Storage Temperature Range.............................-60°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETER
CONDITIONS
UNITS
Operating Supply Voltage V
CC
2.7 5.5 V
f
CLOCK
= 8MHz, no load 3 5 mA
Operating Supply Current I
CC
f
CLOCK
= 32.768kHz, no load 13 25 µA
LOGIC INPUT (SPEED)
Input High Voltage V
IH
0.7 x
V
Input Low Voltage V
IL
0.3 x
V
Input Current I
IN
2µA
CLOCK OUTPUT
VCC = 4.5V, I
SOURCE
= 9mA
V
CC
- 0.4
Output High Voltage V
OH
VCC = 2.7V, I
SOURCE
= 2.5mA
V
CC
- 0.4
V
VCC = 4.5V, I
SINK
= 20mA 0.4
Output Low Voltage V
OL
VCC = 2.7V, I
SINK
= 10mA 0.4
V
VCC = 5V, TA = +25°C (Note 2) -2 +2
Initial Fast CLOCK Frequency
Accuracy
VCC = 2.7V to 5.5V, TA = +25°C -4 +4
%
SYMBOL
MIN TYP MAX
V
CC
f
FCLOCK
V
CC
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MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
_______________________________________________________________________________________ 3
Note 1: All parameters are tested at TA= +25°C. 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.
ELECTRICAL CHARACTERISTICS (continued)
(VCC= 2.7V to 5.5V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at VCC= 5V and TA = +25°C.) (Note 1)
PARAMETER
CONDITIONS
UNITS
Fast CLOCK Frequency
Temperature Sensitivity
(Note 3)
ppm/oC
VCC = 5V, TA = +25°C (Note 2)
Initial Slow CLOCK Frequency
Accuracy
VCC = 2.7V to 5.5V, TA = +25°C
kHz
Slow CLOCK Frequency
Temperature Sensitivity
(Note 3)
ppm/oC
CLOCK Output Duty Cycle 43 50 57 %
CLOCK Output Jitter
Observation of 8MHz output for 20s using a
500MHz oscilloscope
ps
P-P
CLOCK Output Rise Time t
R
10% to 90% 5 ns
CLOCK Output Fall Time t
F
90% to 10% 5 ns
Startup Delay VCC rising from 0 to 5V in 1µs
µs
TA = +25°C
2.2
Output Undervoltage Lockout UVLO VCC rising
T
A
= -40°C to +125°C
V
Output Undervoltage Lockout
Hysteresis
V
THYS
45 mV
SYMBOL
f
SCLOCK
MIN TYP MAX
±50 ±325
32.440 32.768 33.096
31.785 33.751
±50 ±325
160
100
2.15
2.05 2.35
2.25
Page 4
MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
4 _______________________________________________________________________________________
DUTY CYCLE vs. TEMPERATURE
MAX7377 toc01
TEMPERATURE (°C)
DUTY CYCLE (%)
1209545 70-5 20-30
46
47
48
49
50
51
52
53
54
55
45
-55
CLOCK = 32kHz
DUTY CYCLE vs. TEMPERATURE
MAX7377 toc02
TEMPERATURE (°C)
DUTY CYCLE (%)
1209545 70-5 20-30
46
47
48
49
50
51
52
53
54
55
45
-55
CLOCK = 4MHz
DUTY CYCLE vs. SUPPLY VOLTAGE
MAX7377 toc03
SUPPLY VOLTAGE (V)
DUTY CYCLE (%)
5.24.94.6
46
47
48
49
50
51
52
53
54
55
45
4.3 5.5
CLOCK = 32kHz
DUTY CYCLE vs. SUPPLY VOLTAGE
MAX7377 toc04
SUPPLY VOLTAGE (V)
DUTY CYCLE (%)
5.24.94.6
46
47
48
49
50
51
52
53
54
55
45
4.3 5.5
CLOCK = 4MHz
SUPPLY CURRENT vs. TEMPERATURE
MAX7377 toc05
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
1209545 70-5 20-30
10.5
11.0
11.5
12.0
12.5
13.0
13.5
14.0
10.0
-55
CLOCK = 32kHz
SUPPLY CURRENT vs. TEMPERATURE
MAX7377 toc06
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
1209545 70-5 20-30
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
0.5
-55
CLOCK = 4MHz
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7377 toc07
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
5.24.94.6
0
5
10
15
20
25
30
4.3 5.5
CLOCK = 32kHz
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7377 toc08
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.24.94.6
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
0.5
4.3 5.5
CLOCK = 4MHz
FREQUENCY vs. SUPPLY VOLTAGE
MAX7377 toc09
SUPPLY VOLTAGE (V)
FREQUENCY (kHz)
5.24.94.6
30.5
31.0
31.5
32.0
32.5
33.0
33.5
34.0
34.5
35.0
30.0
4.3 5.5
CLOCK = 32kHz
Typical Operating Characteristics
(VCC= 5V, TA= +25°C, unless otherwise noted.)
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MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
_______________________________________________________________________________________ 5
FREQUENCY vs. SUPPLY VOLTAGE
MAX7377 toc10
SUPPLY VOLTAGE (V)
FREQUENCY (MHz)
5.24.94.6
3.92
3.94
3.96
3.98
4.00
4.02
4.04
4.06
4.08
4.10
3.90
4.3 5.5
CLOCK = 4MHz
FREQUENCY vs. TEMPERATURE
MAX7377 toc11
TEMPERATURE (°C)
FREQUENCY (kHz)
1209545 70-5 20-30
32.1
32.2
32.3
32.4
32.5
32.6
32.7
32.8
32.9
33.0
32.0
-55
CLOCK = 32kHz
FREQUENCY vs. TEMPERATURE
MAX7377 toc12
TEMPERATURE (°C)
FREQUENCY (MHz)
1209545 70-5 20-30
3.92
3.94
3.96
3.98
4.00
4.02
4.04
4.06
4.08
4.10
3.90
-55
CLOCK = 4MHz
40ns/div
CLOCK
MAX7377 toc13
CLOCK OUTPUT WAVEFORM (CL = 10pF)
f = 4MHz, CL = 10pF
40ns/div
CLOCK
MAX7377 toc14
CLOCK OUTPUT WAVEFORM (CL = 50pF)
f = 4MHz, CL = 50pF
40ns/div
CLOCK
MAX7377 toc15
CLOCK OUTPUT WAVEFORM (CL = 100pF)
f = 4MHz, CL = 100pF
20µs/div
MAX7377 toc16
HIGH-SPEED TO LOW-SPEED
TRANSITION
400ns/div
MAX7377 toc17
HIGH-SPEED TO LOW-SPEED
TRANSITION (EXPANDED SCALE)
Typical Operating Characteristics (continued)
(VCC= 5V, TA= +25°C, unless otherwise noted.)
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MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VCC= 5V, TA= +25°C, unless otherwise noted.)
Detailed Description
The MAX7377 is a dual-speed clock generator for
microcontrollers (µCs) 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.
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.
Oscillator
The clock output is a push-pull configuration and is
capable of driving a ground-connected 500Ω or a positive-supply-connected 250Ω 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 VCCor 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
Pin Description
PIN NAME FUNCTION
1 CLOCK Push-Pull Clock Output
2 GND Ground
3 SPEED
Clock-Speed Select Input. Drive SPEED low to select the 32kHz fixed frequency. Drive SPEED high to
select factory-trimmed frequency.
4VCCPositive Supply Voltage. Bypass VCC to GND with a 0.1µF capacitor.
5 E.C. Must be Externally Connected to V
CC
LOW-SPEED TO HIGH-SPEED
TRANSITION
20µs/div
MAX7377 toc18
CLOCK
SPEED
LOW-SPEED TO HIGH-SPEED
TRANSISTION (EXPANDED SCALE)
400ns/div
MAX7377 toc19
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MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
_______________________________________________________________________________________ 7
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 500kΩ may be used.
Applications Information
Interfacing to a Microcontroller
Clock Input
The MAX7377 clock output is a push-pull, CMOS, logic
output that directly drives any microprocessor (µP) or
µC 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 µP. 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.
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.
Initial Power-Up and Operation
An internal power-up reset disables the oscillator until
VCChas risen above 2.2V. The clock then starts up
within 30µs (typ) at the frequency determined by the
SPEED pin.
Extended Temperature Operation
The MAX7377 was tested to +135°C 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 -40°C to +125°C at this
time. Contact the factory if operation outside this range
is required.
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 VCCto GND with a
0.1µF 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.
Figure 1. Functional Diagram
V
CC
MAX7377
600kHz TO 10MHz
(HF OSCILLATOR)
SPEED
LOGIC
32kHz
(LF OSCILLATOR)
MUX
POR
CLOCK
Page 8
MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
8 _______________________________________________________________________________________
MAX7377
CLOCK
OSC1
OSC2
µC
I/O PORT
V
CC
SUPPLY VOLTAGE
E.C.
SPEED
Typical Application Circuit
SUFFIX STANDARD FREQUENCY (MHz)
MG 1
OK 1.8432
QT 3.39545
QW 3.6864
RD 4
RH 4.1943
TP 8
Table 1. Standard Frequencies
PART PIN-PACKAGE
FREQUENCY
(Hz)
TOP MARK
MAX7377AXMG 5 SOT23 1M AENE
MAX7377AXOK 5 SOT23 1.8432M AEND
MAX7377AXQT 5 SOT23 3.39545M AEMY
MAX7377AXQW 5 SOT23 3.6864M AEMZ
MAX7377AXRD 5 SOT23 4M AENA
MAX7377AXRH 5 SOT23 4.1943M AENB
MAX7377AXTP 5 SOT23 8M AENC
Table 2. Standard Part Numbers
For all other reset threshold options, contact factory.
Chip Information
TRANSISTOR COUNT: 2027
PROCESS: BiCMOS
Page 9
MAX7377
Silicon Oscillator with Low-Power
Frequency Switching
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
© 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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
E
1
1
21-0057
PACKAGE OUTLINE, SOT-23, 5L
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