MAX706SCSA Maxim Integrated Products, MAX706SCSA Datasheet - Page 8

• Manufacturer Part Number: MAX706SCSA
• Description: IC MPU SUPERVISORY CIRCUIT 8SOIC
• Manufacturer: Maxim Integrated Products
• Type: Simple Reset/Power-On Resetr

Specifications of MAX706SCSA

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active Low
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 2.93V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

WDO can be connected to the nonmaskable interrupt
(NMI) input of a µP. When V
threshold, WDO immediately goes low, even if the
watchdog timer has not timed out (Figure 3). Normally,
this would trigger an NMI, but since reset is asserted
simultaneously, the NMI is overridden. The WDO
should not be connected to RESET directly. Instead,
connect WDO to MR to generate a reset pulse when it
times out.
The manual reset (MR) input allows RESET and RESET
to be activated by a pushbutton switch. The switch is
effectively debounced by the 140ms minimum reset
pulse width. MR can be driven by an external logic line
since it is TTL/CMOS compatible. The minimum MR
+3V Voltage Monitoring, Low-Cost µP
Supervisory Circuits
Figure 3. RESET, RESET, MR, and WDO Timing
Figure 4. MAX706AP/AR/AS/AT Watchdog Timing
8
RESET
RESET
RESET
+3V/+3.3V
+3V/+3.3V
+3V/+3.3V
WDO*
WDO
WDI
MR*
V
CC
_______________________________________________________________________________________
+3.3V
+3.3V
+3.3V
+3.3V
+1V
0V
0V
0V
0V
0V
0V
0V
t
WP
V
RST
t
WD
V
RST
RESET EXTERNALLY
TRIGGERED BY MR
*NOTE: MR EXTERNALLY DRIVEN LOW.
t
RST
WDO TIMING SHOWN FOR MAX706P/R/S/T.
CC
t
WD
drops below the reset
t
MD
Manual Reset
t
MR
t
RST
t
RST
t
WD
input pulse width is 500ns when V
when V
to V
The power-fail comparator can be used for various pur-
poses because its output and noninverting input are
not internally connected. The inverting input is internally
connected to a 1.25V reference. The power-fail com-
parator has 10mV of hysteresis, which prevents repeat-
ed triggering of the power-fail output (PFO).
Figure 5. Monitoring Both +3V/+3.3V and +12V
Figure 6. RESET Valid to GND Circuit
CC
130kΩ
1MΩ
when not used.
CC
1%
1%
( ) ARE FOR MAX706P/AP
+12V RESET
THRESHOLD AT +25°C
+12V
= +5V. Leave MR unconnected or connect
PARAMETER
MAX706AR/AS/AT
+3V/+3.3V
MAX706R/S/T
MAX708R/S/T
RESET
V
PFI
CC
MAX708R/S/T
Power-Fail Comparator
10.24
MIN
MAX706_
GND
10.87
(RESET)
TYP
RESET
PFO
MR
CC
R1
11.50
MAX
= +3V and 150ns
UNIT
V
TO µP