19-3350; Rev 0; 7/04
Silicon Oscillator with Low-Power
Frequency Switching and Reset Output
General Description
The MAX7378 dual-speed silicon oscillator with reset, is
a replacement for ceramic resonators, crystals, crystal-
oscillator modules, and discrete reset circuits. The
MAX7378 provides the primary and secondary clock
source and reset function for microcontrollers in 3V,
3.3V, and 5V applications. The MAX7378 features a
factory-programmed high-speed oscillator, a
32.768kHz oscillator, a clock selector input, and a
microprocessor (µP) power-on-reset (POR) supervisor.
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 MAX7378 is resistant to vibration and EMI.
The high-output-drive current and absence of high-
impedance nodes make the oscillator less susceptible
to dirty or humid operating conditions. With a wide
operating temperature range as standard, the
MAX7378 is a good choice for demanding home appli-
ance, industrial, and automotive environments.
The MAX7378 is available in an 8-pin µMAX
®
package.
Refer to the MAX7384 data sheet for frequencies
≥10MHz.
The MAX7378 standard operating tempera-
ture range is -40°C to +125°C. See the
Applications
Information
section for the extended operating temper-
ature range.
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Features
2.7V to 5.5V Operation
Accurate High-Speed Oscillator: 600kHz to 10MHz
Accurate Low-Speed 32kHz Oscillator
Glitch-Free Switch Between High Speed and Low
Speed at Any Time
Reset Output Holds the µC in Reset for 100µs
After Clock Startup
±10mA Clock-Output Drive Capability
2% Initial Accuracy
±50ppm/°C Temperature Coefficient
50% ±7% Output Duty Cycle
5ns Output Rise and Fall Time
Low Jitter: 160ps (Peak-to-Peak) at 8MHz
2.4mA Fast-Mode Operating Current (8MHz)
11µA Slow-Mode Operating Current (32kHz)
-40°C to +125°C Temperature Range
MAX7378
Ordering Information
PART
MAX7378A _ _ _
MAX7378B _ _ _
TEMP RANGE
-40
o
C to +125
o
C
-40
o
C to +125
o
C
RESET
OUTPUT
Active high
push-pull
Active low
push-pull
PIN-
PACKAGE
8 µMAX
8 µMAX
8 µMAX
Applications
White Goods
Automotive
Consumer Products
Appliances and Controls
Handheld Products
Portable Equipment
Microcontroller (µC) Systems
MAX7378C _ _ _ -40
o
C to +125
o
C Open drain
Standard version is shown in bold. The first letter after the part
number designates the reset output option. Insert the letter cor-
responding to the desired reset threshold level from Table 1 in
the next position. Insert the two-letter code from Table 2 in the
remaining two positions for the desired frequency range. See
Table 3 for standard part numbers.
Typical Application Circuit
SUPPLY VOLTAGE
V
CC
ENABLE
V
L
CLOCK
OSC1
OSC2
Pin Configuration appears at end of data sheet.
MAX7378
RST/RST
RST
I/O PORT
SPEED
µC
µMAX is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________
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.
Silicon Oscillator with Low-Power
Frequency Switching and Reset Output
MAX7378
ABSOLUTE MAXIMUM RATINGS
V
CC
to 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)
8-Pin µMAX (derate 4.5mW/°C above +70°C)....362mW (U8-1)
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
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
CC
= 2.7V to 5.5V, V
L
= V
CC
, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at V
CC
= 5V, T
A
= +25°C.) (Note 1)
PARAMETER
Operating Supply Voltage
Logic Output Supply Voltage
Operating Supply Current
Shutdown Current
LOGIC INPUT (SPEED, ENABLE)
Input High Voltage
Input Low Voltage
Input Current
CLOCK OUTPUT
V
L
= 4.5V, I
SOURCE
= 9mA
Output High Voltage
V
OH
V
L
= 2.7V, I
SOURCE
= 2.5mA
Output Low Voltage
Initial Fast CLOCK Frequency
Accuracy
Fast CLOCK Frequency
Temperature Sensitivity
Initial Slow CLOCK Frequency
Accuracy
Slow CLOCK Frequency
Temperature Sensitivity
f
SCLOCK
V
OL
f
FCLOCK
V
L
= 4.5V, I
SINK
= 20mA
V
L
= 2.7V, I
SINK
= 10mA
V
CC
= 5V, T
A
= +25°C (Note 2)
V
CC
= 2.7V to 5.5V, T
A
= +25°C
(Note 3)
V
CC
= 5V, T
A
= +25°C
V
CC
= 2.7V to 5.5V, T
A
= +25°C
(Note 3)
32.440
31.785
±50
-2
-4
±50
32.768
V
L
-
0.4
V
V
L
-
0.4
0.4
0.4
+2
+4
±325
33.096
33.751
±325
V
%
ppm/
o
C
kHz
ppm/
o
C
V
IH
V
IL
I
IN
0.7 x
V
CC
0.3 x
V
CC
2
V
V
µA
SYMBOL
V
CC
V
L
I
CC
+ I
L
I
CC
+ I
L
I
SHDN
Must be connected to V
CC
f
CLOCK
= 8MHz, no load
f
CLOCK
= 32.768kHz, no load
ENABLE = 0V; I
CC
+ I
L
CONDITIONS
MIN
2.7
2.7
2.4
11
3.0
TYP
MAX
5.5
5.5
5.5
25
7.5
UNITS
V
V
mA
µA
µA
2
_______________________________________________________________________________________
Silicon Oscillator with Low-Power
Frequency Switching and Reset Output
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 2.7V to 5.5V, V
L
= V
CC
, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at V
CC
= 5V, T
A
= +25°C.) (Note 1)
PARAMETER
CLOCK Output Duty Cycle
CLOCK Output Jitter
CLOCK Output Rise Time
CLOCK Output Fall Time
RST/RST OUTPUT
T
A
= +25°C
Reset Threshold
V
TH+
V
CC
rising
T
A
= -40°C to +125°C
Reset Hysteresis
POR Delay
Output High Voltage
Output Low Voltage
V
OH
V
OL
V
THYS
V
HYST
= {(V
TH+
) - ( V
TH-
)}/(V
TH-
) x 100%
V
CC
rising from 0V to (V
TH
+200mV) in 1µs
V
L
= 4.5V, I
SOURCE
= 9mA
V
L
= 2.7V, I
SOURCE
= 2.5mA
V
L
= 4.5V, I
SINK
= 20mA
V
L
= 2.7V, I
SINK
= 10mA
V
L
- 0.4
V
L
- 0.4
0.4
0.4
V
TH
-
1.5%
V
TH
-
5%
2.0
100
V
TH
+
1.5%
V
V
TH
+
5%
%
µs
V
V
t
R
t
F
Observation of 8MHz output for 20s using a
500MHz oscilloscope
10% to 90%
90% to 10%
SYMBOL
CONDITIONS
MIN
43
TYP
50
160
5
5
MAX
57
UNITS
%
ps
P-P
ns
ns
MAX7378
Note 1:
All parameters are tested at T
A
= +25°C. Specifications over temperature are guaranteed by design.
Note 2:
The frequency is determined by part number selection. See the
Ordering Information.
Note 3:
Guaranteed by design. Not production tested.
_______________________________________________________________________________________
3
Silicon Oscillator with Low-Power
Frequency Switching and Reset Output
MAX7378
Typical Operating Characteristics
(V
CC
= V
L
= 5V, T
A
= +25°C, unless otherwise noted.)
DUTY CYCLE vs. TEMPERATURE
MAX7378 toc01
DUTY CYCLE vs. TEMPERATURE
MAX7378 toc02
DUTY CYCLE vs. SUPPLY VOLTAGE
54
53
DUTY CYCLE (%)
52
51
50
49
48
MAX7378 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
-30
-5
20
45
70
95
120
TEMPERATURE (°C)
CLOCK = 4MHz
55
47
46
45
4.3
4.6
CLOCK = 32kHz
4.9
5.2
5.5
SUPPLY VOLTAGE (V)
DUTY CYCLE vs. SUPPLY VOLTAGE
MAX7378 toc04
SUPPLY CURRENT vs. TEMPERATURE
MAX7378 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 = 4 MHz
MAX7378 toc06
55
54
53
DUTY CYCLE (%)
52
51
50
49
48
47
46
45
4.3
4.6
4.9
5.2
CLOCK = 4MHz
14.0
13.5
SUPPLY CURRENT (µA)
13.0
12.5
12.0
11.5
11.0
CLOCK = 32kHz
10.5
10.0
1.5
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
MAX7378 toc07
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7378 toc08
FREQUENCY vs. SUPPLY VOLTAGE
34.5
34.0
FREQUENCY (kHz)
33.5
33.0
32.5
32.0
31.5
31.0
CLOCK = 32kHz
MAX7378 toc09
14
13
SUPPLY CURRENT (µA)
12
11
10
9
CLOCK = 32kHz
8
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
CLOCK = 4MHz
4.3
4.6
4.9
5.2
35.0
30.5
30.0
5.5
4.3
4.6
4.9
5.2
5.5
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
4
_______________________________________________________________________________________
Silicon Oscillator with Low-Power
Frequency Switching and Reset Output
MAX7378
Typical Operating Characteristics (continued)
(V
CC
= V
L
= 5V, T
A
= +25°C, unless otherwise noted.)
FREQUENCY vs. SUPPLY VOLTAGE
MAX7378 toc10
FREQUENCY vs. TEMPERATURE
MAX7378 toc11
FREQUENCY vs. TEMPERATURE
4.08
4.06
FREQUENCY (MHz)
4.04
4.02
4.00
3.98
3.96
MAX7378 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
4.3
4.6
4.9
5.2
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
3.94
3.92
3.90
CLOCK = 4MHz
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)
MAX7378 toc13
CLOCK OUTPUT WAVEFORM (CL = 50pF)
MAX7378 toc14
CLOCK OUTPUT WAVEFORM (CL = 100pF)
MAX7378 toc15
F = 4MHz, CL = 10pF
40ns/div
F = 4MHz, CL = 50pF
40ns/div
F = 4MHz, CL = 100pF
40ns/div
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD
MAXIMUM TRANSIENT DURATION (µs)
MAX7378 toc16
HIGH-SPEED TO LOW-SPEED
TRANSITION
MAX7378 toc17
HIGH-SPEED TO LOW-SPEED
TRANSITION (EXPANDED SCALE)
MAX7378 toc18
1000
RESET OCCURS
ABOVE THE CURVE
100
CLOCK
CLOCK
SPEED
RESET = 4.29V
10
0
200
400
600
800
1000
20µs/div
RESET THRESHOLD OVERDRIVE (mV)
400µs/div
SPEED
_______________________________________________________________________________________
5
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