19-0829; Rev 3; 11/05
Microprocessor Supervisory Circuits
The MAX696/MAX697 supervisory circuits reduce the
complexity and number of components required for
power-supply monitoring and battery-control functions
in microprocessor (µP) systems. These include µP reset
and backup-battery switchover, watchdog timer, CMOS
RAM write protection, and power-failure warning. The
MAX696/MAX697 significantly improve system reliability
and accuracy compared to that obtained with separate
ICs or discrete components.
The MAX696 and MAX697 are supplied in 16-pin packages and perform six functions:
1) A reset output during power-up, power-down, and
brownout conditions. The threshold for this “lowline” reset is adjustable by an external voltagedivider.
2) A reset pulse if the optional watchdog timer has not
been toggled within a specified time.
3) Individual outputs for low-line and watchdog fault
conditions.
4) The reset time may be left at its default value of
50ms, or may be varied with an external capacitor
or clock pulses.
5) A separate 1.3V threshold detector for power-fail
warning, low-battery detection, or to monitor a
power supply other than VCC.
The MAX696 also has battery-backup switching for
CMOS RAM, CMOS microprocessor, or other lowpower logic.
The MAX697 lacks battery-backup switching, but has
write-protection pins (CE IN and CE OUT) for CMOS
RAM or EPROM. In addition, it consumes less than 250
microamperes.
Features
♦ Adjustable Low-Line Monitor and Power-Down
Reset
♦ Power-OK/Reset Time Delay
♦ Watchdog Timer—100ms, 1.6s, or Adjustable
♦ Minimum Component Count
♦ 1µA Standby Current
♦ Battery-Backup Power Switching (MAX696)
♦ On-Board Gating of Chip-Enable Signals
(MAX697)
♦ Separate Monitor for Power-Fail or Low-Battery
Warning
Ordering Information
PART
MAX696C/D
TEMP RANGE
0°C to +70°C
PIN-PACKAGE
Dice
MAX696CPE
0°C to +70°C
16 PDIP
MAX696CWE
0°C to +70°C
16 Wide SO
MAX696EPE
-40°C to +85°C
16 PDIP
MAX696EJE
-40°C to +85°C
16 CERDIP
MAX696EWE
-40°C to +85°C
16 Wide SO
MAX696MJE
-55°C to +125°C
16 CERDIP
Ordering Information continued at end of data sheet.
Devices in PDIP and SO packages are available in both leaded and lead-free packaging. Specify lead free by adding the +
symbol at the end of the part number when ordering. Lead free
not available for CERDIP package.
Pin Configurations
TOP VIEW
Applications
Computers
VBATT
1
16
RESET
Controllers
VOUT
2
15
RESET
VCC
3
14
WDO
Intelligent Instruments
Automotive Systems
MAX696
4
13
LLIN
5
12
N.C.
LOW LINE
6
11
WDI
OSC IN
Typical Operating Circuit appears at end of data sheet.
GND
BATT ON
Critical µP Power Monitoring
7
10
PFO
OSC SEL
8
9
PFI
Pin Configurations continued at end of data sheet.
________________________________________________________________ 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
MAX696/MAX697
General Description
Microprocessor Supervisory Circuits
MAX696/MAX697
ELECTRICAL CHARACTERISTICS (continued)
(VCC = full operating range, VBATT = 2.8V, TA = +25°C, unless otherwise noted.)
PARAMETER
Reset Timeout Delay
CONDITIONS
Figure 6, OSC SEL HIGH, VCC = 5V
MIN
35
Watchdog Timeout Period,
Internal Oscillator
Long period, VCC = 5V
Short period, VCC = 5V
Watchdog Timeout Period,
External Clock
Long period
Short period
Minimum WDI Input Pulse Width
VIL = 0.4V, VIH = 3.5V, VCC = 5V
200
RESET and RESET Output
Voltage (Note 2)
Output Short-Circuit Current
MAX
70
1.00
1.6
2.25
s
70
100
140
ms
4032
4097
960
1025
Clock
cycles
0.4
ISINK = 1.6mA, 3V < VCC < 5.5V
0.4
0.4
3.5
1
3
Logic-low
WDI Input Threshold
VCC = 5V
(Note 3)
Logic-high (MAX696)
3.5
V
20
WDI = 0V
LLIN Input Current
PFO Output Voltage
PFO Short-Circuit Source Current
CHIP-ENABLE GATING (MAX697)
-50
VCC = 3V, 5V
VCC = 3V, 5V
1.2
1.3
±15
±0.01
±0.01
±0.01
MAX697
MAX696
ISINK = 1.6mA
ISOURCE = 1µA, VCC = 5V
PFI = 0V, PFO = 0V
VIH, VCC = 5V
-25
-500
3.5
1
3
25
µA
3
nA
V
V
µA
0.4
ISOURCE = 800µA
VCC 0.5V
ISOURCE = 1µA, VCC = 0V
CE Propagation Delay
V
mV
nA
0.8
ISINK = 1.6mA
µA
1.4
±50
±25
+25
+25
0.4
3.0
CE IN Pullup Current
CE OUT Output Voltage
50
-15
VIL
CE IN Thresholds
µA
3.8
WDI = VOUT
POWER-FAIL DETECTOR
PFI Input Threshold
PFI - LLIN Threshold Difference
PFI Input Current
25
V
0.8
Logic-high (MAX697)
WDI Input Current
V
3.5
ISINK = 800µA, TA = full
ISOURCE = 1µA, VCC = 5V, TA = full
RESET, RESET, WDO, LOW LINE
UNITS
ms
ns
ISINK = 400µA, VCC = 2V, VBATT = 0V
ISOURCE = 1µA, VCC = 5V
LOW LINE and WDO Output
Voltage
TYP
50
VCC 0.05V
VCC = 5V
V
80
150
ns
OSCILLATOR
OSC IN Input Current
±2
OSC IN Frequency Range
OSC SEL = 0V
OSC IN Frequency with External
Capacitor
OSC SEL = 0V, COSC = 47pF
µA
5
OSC SEL Input Pullup Current
µA
0
250
4
kHz
kHz
Note 2: TA = full operating range.
Note 3: WDI is guaranteed to be in the mid-level (inactive) state if WDI is floating and VCC is in the operating voltage range. WDI is
internally biased to 38% of VCC with an impedance of approximately 125kΩ.
_______________________________________________________________________________________
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