Voltage Supervisor. MIC1232 Datasheet
5V Voltage Supervisor with Manual Reset,
Watchdog Timer and Dual Reset Outputs
The MIC1232 is a low-current microprocessor supervisor
for monitoring 5V systems. The device features logic
selectable (TOL) reset thresholds of 5% or 10% of 5V; a
pushbutton reset input (/PBRST); a watchdog timer with
three-state selectable (TD) timeout periods of 150ms,
600ms, or 1.2s; a fixed reset timeout period of 250ms
(min); and active-low open-drain reset (/RST) and active-
high push-pull reset (RST) outputs. The /RST output
maintains a valid reset condition for VCC as low as 1.4V.
The MIC1232 asserts a reset condition if the supply
voltage drops below the reset threshold, the pushbutton
reset is asserted low, or the watchdog timer does not see
a high-to-low transition on the watchdog timer input within
the watchdog timer period. A reset condition is held for the
reset timeout period of 250ms (min) after the pushbutton
input is released or after the supply voltage increases
above the reset threshold voltage.
The MIC1232 is a drop-in replacement for the DS1232,
MAX1232, and TC1232. It consumes a low 18µA (typ) of
supply current, 40µA (max). This is one-tenth the max
current of the DS1232, and one-quarter the max current of
the MAX1232 and TC1232. It operates over the –40C to
+85C temperature range and is available in the Pb-Free
8-pin SOIC and PDIP packages.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
• Low-current version of
• Low current: 18µA (typ), 40µA (max)
• Selectable threshold (TOL): 5% or 10% of 5V
• Selectable watchdog timer (TD): 150ms, 600ms, 1.2s
• Power OK/Reset time delay: 250ms (min)
• Debounced pushbutton reset input (/PBRST)
• Dual complementary reset outputs
– Active-low, open-drain reset output
– Active-high, push-pull reset output
• Available in Pb-Free 8-pin SOIC and PDIP packages
• –40°C to +85°C temperature range
• Pin-for-Pin compatible with MIC1832/DS1832/CAT1832
• Automotive systems
• Intelligent systems
• Critical microprocessor power monitoring
• Battery powered computers
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
–40° to +85°C
–40° to +85°C
Pin Number Pin Name
Pushbutton Reset input: This input is debounced and can be driven with external logic signals or by
using a mechanical pushbutton to actively force a reset. All pulses less than 1ms in duration on the
/PBRST pin are ignored; any pulse with a duration of 20ms or greater is guaranteed to cause a
Time Delay input: This input selects the timebase used by the watchdog timer. When TD = 0V, the
watchdog timeout period is set to a normal value of 150ms. When TD = open, the watchdog timeout
period is set to a nominal value of 600ms. When TD = VCC, the watchdog period is 1.2s nominally.
Tolerance Select input: This input selects whether 5% or 10% of VCC is used as the reset threshold
voltage. When TOL = 0V, the 5% tolerance level is selected and when TOL = VCC, a 10% tolerance
level is selected.
IC ground pin, 0V reference.
RST is asserted high if either VCC goes below the reset threshold, the watchdog times out, or
/PBRST is pulled low for a minimum of 20ms. RST remains asserted for one reset timeout period
after VCC exceeds the reset threshold, after the watch times out, or after /PBRST goes high.
/RST is asserted low if either VCC goes below the reset threshold, the watchdog times out, or
/PBRST is pulled low for a minimum of 20ms. /RST remains asserted for one reset timeout period
after VCC exceeds the reset threshold, after the watch times out, or after /PBRST goes high. Open-
Input to watchdog timer. If /ST does not see a transition from high to low within the watchdog
timeout period, RST and /RST will be asserted.
Primary supply input, +5V.