MIC1832(Old_V) Ver la hoja de datos (PDF) - Micrel
Número de pieza
componentes Descripción
Lista de partido
MIC1832 Datasheet PDF : 8 Pages
| |||
MIC1832 µP Supervisory Circuit
Circuit Description
Power Monitor
The RST and RST pins are asserted whenever VCC
falls below the reset threshold voltage as determined by
the TOL pin. A 5% tolerance level (2.88V reset
threshold voltage) can be selected by connecting the
TOL pin to ground and a 10% tolerance (2.55V reset
threshold voltage) can be selected by connecting the
TOL pin to VCC. The reset pins will remain asserted for
a period of 250ms after VCC has risen above the reset
threshold voltage. The reset function ensures the
microprocessor is properly reset and powers up into a
known condition after a power failure. RST will remain
valid with VCC as low as 1.4V.
8++62
8++
456
J42,
456
8++62
J427
Figure 1. Power-Up/Power-Down Sequence
J56
56
J6,
Note:
The maximum time between high-to-low transitions (tTD) on the
watchdog input (ST) is determined by the voltage applied to the
TD pin. If the watchdog input sees a high-to-low transition prior to
the timeout period, the watchdog timer will be reset.
Figure 2. Watchdog Input
Watchdog Timer
The microprocessor can be monitored by connecting
the ST pin (watchdog input) to a bus line or I/O line. If a
high-to-low transition doesn’t occur on the ST pin within
the watchdog timeout period (determined by TD pin, see
Table 1), the RST and RST pins will be asserted
resulting in a microprocessor reset. RST and RST will
remain asserted for at least 250ms when this occurs. A
minimum pulse of 75ns or any transition high-to-low on
the ST pin will reset the watchdog timer. The watchdog
timer will be reset if ST sees a valid transition within the
watchdog timeout period.
tPB
Pushbutton Reset Input
tPDLY
The PBRST input can be driven with a manual
PBRST
pushbutton switch or with external logic signals. The
tRST
input is internally debounced and requires an active low
signal to force the reset outputs into their active states.
RST
The PBRST input will recognize any pulse that is 20ms
in duration or greater and will ignore all pulses that are
RST
less than 1ms in duration.
Figure 3. Pushbutton Reset
6
Share Link: 