MAXIM MAX7388SRFF

19-3896; Rev 1; 1/06
System Monitoring Oscillator with
Watchdog and Power Fail
Features
The MAX7387/MAX7388 replace ceramic resonators,
crystals, and supervisory functions for microcontrollers
in 3.3V and 5V applications.
The MAX7387/MAX7388 provide a clock source together
with integrated reset, watchdog, and power-fail functions. The watchdog timer is pin programmable and
provides watchdog timeout values in the 16ms to
2048ms range. The power-fail output provides early
warning of power failure. The power-fail threshold on the
MAX7388 is internally set. The MAX7387 also provides
a separate watchdog output that is used as a status
indicator or to control safety-critical system elements.
The MAX7387/MAX7388 clock outputs are factory programmed to a frequency in the 1MHz to 16MHz range.
Four standard frequencies are available. Other frequencies are available upon request. The maximum operating
supply current is 5.5mA (max) with a clock frequency of
12MHz.
♦ Robust Microcontroller Clock and Supervisor in a
Single Package
Unlike typical crystal and ceramic resonator oscillator
circuits, the MAX7387/MAX7388 are resistant to EMI
and vibration, and operate reliably at high temperatures. The high-output drive current and absence of
high-impedance nodes make the oscillator invulnerable
to dirty or humid operating conditions.
The MAX7387/MAX7388 are available in 10-pin and 8-pin
µMAX® packages, respectively. The MAX7387/MAX7388
standard operating temperature range is from -40°C to
+125°C.
♦ 5.5mA Operating Current (12MHz)
Applications
White Goods
Handheld Products
Automotive
Portable Equipment
Appliances and Controls
Microcontroller Systems
µMAX is a registered trademark of Maxim Integrated Products, Inc.
♦ Integrated Reset, Watchdog, and Power-Fail
Functions
♦ Pin-Programmable Watchdog Timeout
♦ +2.7V to +5.5V Operation
♦ Factory-Trimmed Oscillator
♦ Reset Valid Down to 1.1V Supply Voltage
♦ ±10mA Clock-Output Drive Current
♦ ±4% Total Accuracy for -40°C to +125°C
♦ ±2.75% Total Accuracy for 0°C to +85°C
♦ -40°C to +125°C Temperature Range
♦ 8- and 10-Pin µMAX Surface-Mount Packages
♦ 1MHz to 16MHz Factory Preset Frequency
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE PKG CODE
MAX7387srff -40oC to +125oC 10 µMAX
U10-2
MAX7388srff -40oC to +125oC 8 µMAX
U8-1
Note: “s” is a placeholder for the reset output type. Insert the
symbol found in Table 3 in the place of “s.” “r” is a placeholder
for the power-on reset (POR) voltage. Insert the symbol found in
Table 2 in the place of “r.” “ff” is a placeholder for the nominal
output frequency. Insert the symbol found in Table 4 in the
place of “ff.” For example, MAX7387CMTP describes a device
with 4.38V reset level, open-collector RST output, and a clock
output frequency of 8MHz.
Typical Application Circuit, Functional Diagram, and Selector
Guide appear at end of data sheet.
Pin Configurations
TOP VIEW
TOP VIEW
PFI 1
10 CLOCK
VCC
2
9
RST/RST
WDS1
3
8
WDI
WDS2
4
7
PFO
GND
5
6
WDO
MAX7387
µMAX
VCC
1
8
CLOCK
WDS1
2
7
RST/RST
3
6
WDI
GND 4
5
PFO
MAX7388
WDS2
µMAX
________________________________________________________________ Maxim Integrated Products
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.
1
MAX7387/MAX7388
General Description
MAX7387/MAX7388
System Monitoring Oscillator with
Watchdog and Power Fail
ABSOLUTE MAXIMUM RATINGS
VCC to GND ...........................................................-0.3V to +6.0V
All Other Pins to GND ................................-0.3V to (VCC + 0.3V)
CLOCK, PFO Output Current, RST/RST, WDO.................±50mA
Continuous Power Dissipation (TA = +70°C)
10-Pin µMAX (derate 5.6mW/°C over +70°C) ..............444mW
8-Pin µMAX (derate 4.5mW/°C over +70°C) ................362mW
Operating Temperature Range .........................-40°C to +125°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
(Typical Application Circuit, VCC = +2.7V to +5.5V, TA = -40°C to +125°C, 1MHz to 16MHz output frequency range, typical values at
VCC = +5.0V, TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
POWER REQUIREMENTS
Operating Supply Voltage
Valid RST/RST Supply Voltage
Operating Supply Current
VCC
VCCR
ICC
2.7
TA = 0°C to +85°C
1.1
TA = -40°C to +125°C
1.18
fCLOCK = 12MHz
5.5
fCLOCK = 8MHz
4.5
V
mA
TRI-LEVEL ANALOG INPUTS: WDS1, WDS2
Input-High Voltage Level
VCC - 0.55V
Input-Middle Voltage Level
V
0.9
VCC - 1.1V
Input-Low Voltage Level
V
0.45
V
0.5
µA
LOGIC INPUT: WDI
Input Leakage Current
ILEAK
Logic-Input High Voltage
VIH
Logic-Input Low Voltage
VIL
Input high
0.7 x VCC
V
0.3 x VCC
V
PUSH-PULL LOGIC OUTPUTS: RST/RST
Output High
VOH
ISOURCE = 1mA
Output Low
VOL
ISINK = 3mA
VCC - 1.5
V
0.05
0.4
V
0.05
0.4
V
0.3
V
OPEN-DRAIN LOGIC OUTPUTS: RST, PFO, WDO
Output Low
VOLO
ISINK = 3mA
Output High Voltage
VOHC
ISOURCE = 5mA
Output Low Voltage
VOLC
ISINK = 5mA
OUTPUT: CLOCK
CLOCK Accuracy
fCLOCK
TA = 0°C to +85°C, VCC = 5.0V
TA = -40°C to +125°C, VCC = 5.0V
VCC - 0.3
V
-2.75
+2.75
-4
+4
%
Clock Frequency Temperature
Coefficient
VCC = 5.0V (Note 2)
140
400
ppm/°C
Clock Frequency Supply
Voltage Coefficient
TA = +25°C (Note 2)
0.67
1
%/V
CLOCK Duty Cycle
(Note 2)
50
55
%
2
45
_______________________________________________________________________________________
System Monitoring Oscillator with
Watchdog and Power Fail
(Typical Application Circuit, VCC = +2.7V to +5.5V, TA = -40°C to +125°C, 1MHz to 16MHz output frequency range, typical values at
VCC = +5.0V, TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
Output Rise Time
tR
Observation for 20s using a 500MHz
oscilloscope
CLOAD = 10pF, 10% to 90% of full scale (Note 2)
Output Fall Time
tF
CLOAD = 10pF, 90% to 10% of full scale (Note 2)
CLOCK Output Jitter
MIN
TYP
MAX
UNITS
ps
310
RMS
2.5
7.0
ns
2.8
7.5
ns
INTERNAL POWER-ON RESET
VTH+
VTH
- 1.5%
VTH
+ 1.5%
TA = -40°C to +125°C
VTH
- 2.5%
VTH
+ 2.5%
V
µs
VCC rising, Table 2
Reset Voltage
Reset Timeout Period
TA = +25°C
0.98 x
VTH+
VTH-
VCC falling
tRST
Figures 1, 2
86
135
250
WDS1 = GND, WDS2 = GND
11
16
22
WDS1 = open, WDS2 = GND
22
32
44
WDS1 = VCC, WDS2 = GND
44
64
88
WDS1 = GND, WDS2 = open
88
128
177
WDS1 = open, WDS2 = open
177
256
354
WDS1 = VCC, WDS2 = open
354
512
708
WDS1 = GND, WDS2 = VCC
708
1024
1416
WDS1 = open, WDS2 = VCC
1416
2048
2832
WATCHDOG
Watchdog Timeout Period
(Figure 2)
tWDG
ms
WDS1 = WDS2 = VCC (watchdog disabled)
POWER FAIL
0.65 x
VCC
0.85 x
VCC
V
4.38
4.60
V
1.0
2
4.0
%VITH
PFI rising
0.9
1.1
1.4
V
PFI falling
1.0
3.5
8.0
%VETH
Power-Fail Select Threshold
VSEL
PFI input
VCC Monitoring Threshold
(Internal Threshold)
VITH
VCC rising
4.06
VIHYST
VCC falling
VETH
VEHYST
Internal Threshold Hysteresis
PFI Monitoring Threshold
(External Threshold)
External Threshold Hysteresis
Note 1: All parameters are tested at TA = +25°C. Specifications over temperature are guaranteed by design.
Note 2: Guaranteed by design. Not production tested.
_______________________________________________________________________________________
3
MAX7387/MAX7388
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(Typical Application Circuit, VCC = +5V, TA = +25°C, unless otherwise noted.)
FREQUENCY vs. TEMPERATURE
0.990
MAX7387/88 toc02
1.020
0.980
1.010
1.000
4.20
4.85
50
49
5.50
VTH+ = +2.9V
NORMALIZED TO TA = +25°C
0.980
3.55
51
0.990
NORMALIZED TO VCC = +5V
VTH+ = +2.9V
2.90
DUTY CYCLE vs. SUPPLY VOLTAGE
52
DUTY CYCLE (%)
1.000
1.030
NORMALIZED FREQUENCY
MAX7387/88 toc01
NORMALIZED FREQUENCY
1.010
1.040
MAX7387/88 toc03
FREQUENCY vs. SUPPLY VOLTAGE
1.020
48
-40 -25 -10 5 20 35 50 65 80 95 110 125
2.90
3.55
4.20
TEMPERATURE (°C)
VCC (V)
DUTY CYCLE vs. TEMPERATURE
CLOCK OUTPUT WAVEFORM
WITH CL = 10pF
CLOCK OUTPUT WAVEFORM
WITH CL = 50pF
MAX7387/88 toc05
MAX7387/88 toc04
51
5.50
4.85
VCC (V)
52
DUTY CYCLE (%)
MAX7387/88 toc06
VCC = +3.3V
VCC = +3.3V
CLOCK
1V/div
50
CLOCK
1V/div
49
48
40ns/div
-40 -25 -10 5 20 35 50 65 80 95 110 125
40ns/div
TEMPERATURE (°C)
SUPPLY CURRENT vs. TEMPERATURE
4
CLOCK
1V/div
SUPPLY CURRENT vs. SUPPLY VOLTAGE
5
MAX7387/88 toc08
5
VCC = 5V
3
VCC = 3.3V
4
ICC (mA)
MAX7387/88 toc07
MAX7387/88 toc09
CLOCK OUTPUT WAVEFORM
WITH CL = 100pF
ICC (mA)
MAX7387/MAX7388
System Monitoring Oscillator with
Watchdog and Power Fail
3
2
2
1
1
VTH+ = 2.9V
40ns/div
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
4
2.90
3.55
4.20
VCC (V)
_______________________________________________________________________________________
4.85
5.50
System Monitoring Oscillator with
Watchdog and Power Fail
MAXIMUM VCC TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
POWER-ON RESET BEHAVIOR
MAX7387/88 toc11
VCC
2V/div
1000
VCC
2V/div
CLOCK
5V/div
CLOCK
2V/div
tRST
RST
5V/div
PFI = VCC PFO
5V/div
1µs/div
TRANSIENT DURATION (µs)
MAX7387/88 toc10
MAX7387/88 toc12
CLOCK SETTLING TIME FROM START
RESET OCCURS ABOVE THIS CURVE
100
10
VCC FALLING FROM VTH+ + 100mV
1
100 200 300 400 500 600 700 800 900 1000
100µs/div
RESET THRESHOLD OVERDRIVE (mV)
RESPONSE OF RST AND WDO
WDI EXCEEDING tWDG
RISING THRESHOLD vs. TEMPERATURE
MAX7387/88 toc13
WDI
2V/div
RST
5V/div
tRST
2.88
VTH+ (V)
WDO
5V/div
tWDG
MAX7387/88 toc14
2.90
2.86
2.84
2.82
2.80
2ms/div
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
_______________________________________________________________________________________
5
MAX7387/MAX7388
Typical Operating Characteristics (continued)
(Typical Application Circuit, VCC = +5V, TA = +25°C, unless otherwise noted.)
System Monitoring Oscillator with
Watchdog and Power Fail
MAX7387/MAX7388
Pin Description
PIN
NAME
FUNCTION
MAX7387
MAX7388
1

PFI
Power-Fail Input. PFI monitors the condition of either an external supplied voltage or VCC.
See the Power Fail section for more details.
2
1
VCC
Power Input. Connect VCC to the power supply. Bypass VCC to GND with a 1µF capacitor.
Install the bypass capacitor as close to the device as possible.
3
2
WDS1
Watchdog Timeout Select Input 1. Connect WDS1 and WDS2 to VCC, GND, or VCC/2, as
shown in Table 1, to set the watchdog timeout period.
4
3
WDS2
Watchdog Timeout Select Input 2. Connect WDS2 and WDS1 to VCC, GND, or VCC/2, as
shown in Table 1, to set the watchdog timeout period.
5
4
GND
Ground
6

WDO
Watchdog Output. Open-drain watchdog output asserts low if WDI is not toggled within the
watchdog timeout period.
7
5
PFO
Power-Fail Output. Open-drain output asserts when the voltage being monitored drops below
the power-fail threshold voltage.
WDI
Watchdog Input. A rising edge on WDI resets the watchdog timer. If WDI does not receive a
rising edge within the watchdog timeout period (tWDG), RST/RST asserts. The watchdog
timeout period is programmable through WDS1 and WDS2. Connect WDS1 and WDS2 to
VCC to disable watchdog timer.
8
6
9
7
RST/RST
Reset Output. Reset output is available in one of three configurations: push-pull RST,
push-pull RST, or open-drain RST. The reset output occurs if any combination of the following
conditions occurs: reset output is asserted during power-up and whenever VCC is below the
reset threshold level; for devices with WDI, reset output asserts when WDI does not receive a
rising edge within the watchdog timeout period.
10
8
CLOCK
Clock Output
Detailed Description
The MAX7387/MAX7388 replace ceramic resonators,
crystals, and supervisory functions for microcontrollers
in 3.3V and 5V applications.
The MAX7387/MAX7388 provide a clock source together
with integrated reset, watchdog, and power-fail functions. The watchdog timer is pin programmable and provides watchdog timeout values in the 16ms to 2048ms
range. The power-fail output provides early warning of
power failure. The power-fail threshold on the MAX7388
is internally set. The MAX7387 features a programmable
power-fail threshold, which is configurable to detect
either an external voltage or the VCC supply voltage to
the device. The MAX7387 also provides a separate
watchdog output that is used as a status indicator or to
control safety-critical system elements.
6
The integrated reset and watchdog functions provide
the power-supply monitoring functions necessary to
ensure correct microcontroller operation. The reset circuit has built-in power-supply transient immunity and
provides both power-on reset and power-fail or
brownout reset functionality. Two standard factorytrimmed reset levels are available. The watchdog timer
is programmable to eight individual timeout values and
may be disabled for test purposes.
A power-fail function is provided for power-supply voltage monitoring and can provide advance notice of an
impending power failure. Parts with power-fail input
(MAX7387) monitor external power-supply voltages
through an external resistive divider. Connect PFI to
VCC to monitor VCC.
_______________________________________________________________________________________
System Monitoring Oscillator with
Watchdog and Power Fail
Reset
The reset function drives the microcontroller reset input
to prevent operation in the cases of the initial power-on
setting, low power-supply voltages, and the failed
watchdog operations. Three reset output versions are
available: push-pull RST, push-pull RST, and open-drain
RST. The reset timeout period (tRST) is nominally 135s.
Power-On Reset (POR)
The internal power-on reset (POR) circuit detects the
power-supply voltage (VCC) level at startup. The POR
circuit starts the oscillator when VCC exceeds the reset
rising threshold level (VTH+). The reset output remains
asserted from the time VCC crosses the VTH+ and continues to be asserted for the reset timeout period (tRST).
Upon completion of the reset timeout, the reset output
is released. See Figure 1.
Low-Voltage Lockout
The reset output asserts whenever VCC drops below the
reset falling threshold, VTH-. The difference between the
reset rising and falling threshold values is VTH+ - (VTH-).
The nominal hysteresis value is 2% of the reset rising
threshold value. The reset detection circuitry provides
filtering to prevent triggering on negative voltage
spikes. See the Maximum VCC Transient Duration vs.
Reset Threshold Overdrive typical operating circuit.
Figure 1 shows the reset output (RST/RST) behavior
during power-up and brownout.
Watchdog
The watchdog function provides microprocessor monitoring by requiring the microprocessor to toggle an output pin to indicate correct operation. The WDI input
monitors the port signal and resets the watchdog timer
on receipt of a rising edge. If an edge is not received
within the required watchdog timeout period, the watchdog circuit initiates a reset cycle. The internal watchdog
5
VITH
VCC (V)
4
VITH - VIHYST
VTH+
3
VTH-
2
1
VCCR
CLK
tRST
RST
PFO
CLOCK STARTS ON INTERNAL
POR (VTH+, VCC RISING)
RST RELEASES AFTER THE
RESET TIMEOUT PERIOD
PFO ASSERTS AS VCC DROPS
BELOW VITH - VIHYST
RST ASSERTS ON RESET FALLING
VOLTAGE (VTH-, VCC FALLING);
CLOCK STOPS
RST CONTINUES TO
ASSERT UNTIL VCCR
Figure 1. RST/RST and PFO Behavior During Power-Up and Brownout
_______________________________________________________________________________________
7
MAX7387/MAX7388
Clock Output (CLOCK)
The push-pull clock output (CLOCK) drives a groundconnected 1kΩ load or a positive supply connected
500Ω load to within 300mV of either supply rail. CLOCK
remains stable over the full operating voltage range and
does not generate short output cycles during either
power-on or power-off. A typical startup characteristic is
shown in the Typical Operating Characteristics section.
MAX7387/MAX7388
System Monitoring Oscillator with
Watchdog and Power Fail
circuits are reset and the watchdog timer restarts at the
end of the reset cycle (RST/RST output releases).
For the MAX7387, the WDO output asserts if the WDI
input does not receive a rising edge within the watchdog
timeout period. WDO output remains asserted until a
valid edge is received on the WDI input, signifying correct microprocessor operation. The WDO output can be
used as a status indicator either to the microprocessor
or to an external device, such as a fault-indicating LED
or sounder. The WDO output is an open-drain output.
The power-up condition of the WDO output is high
(not asserted).
The operation of the watchdog and reset function is
illustrated in Figure 2.
The watchdog timeout period is set to one of nine possible
values by pin strapping WDS1 and WDS2. Each control
input has three possible values assigned by connection
to GND, V CC , or V CC /2 (see Table 1). One of the
assigned values disables the watchdog function and is
intended for customer use during test. The watchdog
timer is disabled while the RST/RST output is asserted.
Power Fail
MAX7388 Power Fail
The power-fail function provides early warning of a power
failure. The power-fail comparator threshold is internally
set to 4.38V VCC rising threshold (VITH). The open-drain
PFO asserts low if the VCC supply voltage drops below
the VCC falling threshold value. The VCC falling threshold
is nominally 2% below the VCC rising threshold.
MAX7387 Power Fail
Internal (VCC) detection is configured by connecting
PFI to VCC. The internal VCC rising threshold (VITH) is
set at 4.38V. The open-drain PFO asserts low if the VCC
supply voltage drops below the VCC falling threshold
value (VHYST). The VCC falling threshold is nominally
2% below the VCC rising threshold.
Applications Information
Interfacing to a Microcontroller
Clock Input
The CLOCK output is a push-pull, CMOS logic output,
which directly drives any microprocessor (µP) or microcontroller (µC) clock input. There are no impedance-
Table 1. Watchdog Timeout Periods
WATCHDOG TIMEOUT
PERIOD (ms)
WDS1
WDS2
MIN
TYP
MAX
GND
GND
11
16
22
VCC/2 = open
GND
22
32
44
VCC
GND
44
64
88
GND
VCC/2 = open
88
128
177
VCC/2 = open
VCC/2 = open
177
256
354
VCC
VCC/2 = open
354
512
708
GND
VCC
708
1024
1416
VCC/2 = open
VCC
1416
2048
2832
VCC
VCC
Disabled
Note: WDS1 or WDS2 is pulled to open if left floating.
VCC
CLK
RESET TIMEOUT PERIOD
(tRST)
RST
INTERNAL
WATCHDOG STATE
ACTIVE
TRIPPED
WDI
WDO
WATCHDOG TIMEOUT
PERIOD (tWDG)
Figure 2. Watchdog Timing Diagram
8
_______________________________________________________________________________________
System Monitoring Oscillator with
Watchdog and Power Fail
Power-Supply Consideration
The MAX7387/MAX7388 operate 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 MAX7387/MAX7388.
Bypass VCC to GND with a 0.1µF surface-mount ceramic
capacitor. Mount the bypass capacitor as close to the
device as possible. If possible, mount the MAX7387
/MAX7388 close to the microcontroller’s decoupling
capacitor so that additional decoupling is not required.
A larger-value bypass capacitor is recommended if the
MAX7387/MAX7388 are to operate with a large capacitive
Table 2. POR Voltage
POWER-ON RESET VOLTAGE (VTH)
r
4.38
M
3.96
J
3.44
N
3.34
P
3.13
Q
2.89
S
2.82
V
2.5
X
load. Use a bypass capacitor value of at least 1000
times that of the output load capacitance.
Output Jitter
The MAX7387/MAX7388s’ jitter performance is given in
the Electrical Characteristics table as a peak-to-peak
value obtained by observing the output of the device for
20s with a 500MHz oscilloscope. Jitter measurements
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 all clock sources degrades in
the presence of mechanical and electrical interference.
The MAX7387/MAX7388 are immune to vibration,
shock, and EMI influences, and thus provide a considerably more robust clock source than crystal- or ceramic-resonator-based oscillator circuits.
Table 3. Reset Output Type
OUTPUT TYPE
s
Push-pull RST
A
Push-pull RST
B
Open-drain RST
C
Note: Standard values are shown in bold. Contact factory for
other output types.
Table 4. Clock Output Frequency
Note: Standard values are shown in bold. Contact factory for
other POR voltages.
CLOCK FREQUENCY (fCLOCK) (MHz)
ff
4
RD
8
TP
12
VB
16
Note: Contact factory for other frequencies.
WB
Selector Guide
PART
FREQUENCY
RANGE (MHz)
RESET
FUNCTION
WATCHDOG INPUT (WDI)/
WATCHDOG OUTPUT (WDO)
POWER-FAIL INPUT (PFI)/
PINSPEED
POWER-FAIL OUTPUT (PFO)
PACKAGE
MAX7387
1 to 16
Yes
Yes/yes
Yes/yes
—
10 µMAX
MAX7388
1 to 16
Yes
Yes/no
No/yes
—
8 µMAX
MAX7389
1 to 16
Yes
Yes/yes
—
—
8 µMAX
MAX7390
1 to 16
Yes
Yes/no
—
Yes
8 µMAX
MAX7391
1 to 16
Yes
—
Yes/yes
Yes
8 µMAX
Note: Other versions with different features are available. Refer to the MAX7389/MAX7390 and MAX7391 data sheets.
_______________________________________________________________________________________
9
MAX7387/MAX7388
matching issues when using the MAX7387/MAX7388.
Operate the MAX7387/MAX7388 and microcontroller
(or other clock input device) from the same supply voltage level. Refer to the microcontroller data sheet for
clock-input compatibility with external clock signals.
The MAX7387/MAX7388 require no biasing components or load capacitance. When using the MAX7387/
MAX7388 to retrofit a crystal oscillator, remove all biasing components from the oscillator input.
System Monitoring Oscillator with
Watchdog and Power Fail
MAX7387/MAX7388
Functional Diagram
RST/RST
MAX7387
MAX7388
PRESCALER
POWER-ON
RESET
RESET TIMER
OSCILLATOR
CLOCK
WDO*
WATCHDOG
TIMER
WDI
N
WDS1
WDS2
PFI*
PFO
INTERNAL (VCC DETECTION)
N
V_TH
*MAX7387 ONLY
GND
Typical Application Circuit
POWER
SUPPLY
DC-DC
5V
WDS1
VCC
R1
RST/RST
WDS2
PFI*
RST/RST
PFO
INT
WDI
I/O PORT
WDO*
I/O PORT
MAX7387
MAX7388
µC
R2
CLOCK
OSC1
GND
*MAX7387 ONLY
Chip Information
PROCESS: BICMOS
10
______________________________________________________________________________________
System Monitoring Oscillator with
Watchdog and Power Fail
8
INCHES
DIM
A
A1
A2
b
E
Ø0.50±0.1
H
c
D
e
E
H
0.6±0.1
L
1
1
α
0.6±0.1
S
BOTTOM VIEW
D
MIN
0.002
0.030
MAX
0.043
0.006
0.037
0.014
0.010
0.007
0.005
0.120
0.116
0.0256 BSC
0.120
0.116
0.198
0.188
0.026
0.016
6°
0°
0.0207 BSC
8LUMAXD.EPS
4X S
8
MILLIMETERS
MAX
MIN
0.05
0.75
1.10
0.15
0.95
0.25
0.36
0.13
0.18
2.95
3.05
0.65 BSC
2.95
3.05
4.78
5.03
0.41
0.66
0°
6°
0.5250 BSC
TOP VIEW
A1
A2
A
α
c
e
b
FRONT VIEW
L
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0036
REV.
J
1
1
______________________________________________________________________________________
11
MAX7387/MAX7388
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 Information (continued)
(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.)
e
10LUMAX.EPS
MAX7387/MAX7388
System Monitoring Oscillator with
Watchdog and Power Fail
4X S
10
10
INCHES
H
Ø0.50±0.1
0.6±0.1
1
1
0.6±0.1
BOTTOM VIEW
TOP VIEW
D2
MILLIMETERS
MAX
DIM MIN
0.043
A
0.006
A1
0.002
A2
0.030
0.037
0.120
D1
0.116
0.118
0.114
D2
0.116
0.120
E1
0.118
E2
0.114
0.199
H
0.187
L
0.0157 0.0275
L1
0.037 REF
b
0.007
0.0106
e
0.0197 BSC
c
0.0035 0.0078
0.0196 REF
S
α
0°
6°
MAX
MIN
1.10
0.15
0.05
0.75
0.95
3.05
2.95
3.00
2.89
3.05
2.95
2.89
3.00
4.75
5.05
0.40
0.70
0.940 REF
0.177
0.270
0.500 BSC
0.090
0.200
0.498 REF
0°
6°
E2
GAGE PLANE
A2
c
A
b
A1
α
E1
D1
L
L1
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 10L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0061
REV.
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.