MM1095

Features:

` Built-in watchdog timer
` Low minimum operating voltage 100A typ.
` Low operating limit voltage Vcc=0.8V
` Watchdog stop function (RCT pin)
` Few external parts

Application

· Reset circuits in microcomputers, CPUs and MPUs
· Logic circuit reset circuits
· Microcomputer system monitoring, etc.

Specifications

Item	Symbol	Rating	Units
Power supply voltage	VCC max.	-0.3~+10	V
CK pin input voltage	VCK	-0.3~VCC+0.3 ( +10)	V
VS pin input voltage	VVS	-0.3~VCC+0.3 ( +10)	V
Voltage applied to RCT pin	VRCT	-0.3~VCC+0.3 ( +10)	V
Voltage applied to RESET pin	VOH	-0.3~VCC+0.3 ( +10)	V
Allowable loss	Pd	400	mW
Storage temperature	TSTG	-40~+125

Description

1. RESET goes low when VCC rises to approximately 0.8V.
2. Capacitor CT charging starts when V_CC rises to V_SH (MM1095A .=. 3.25V, MM1095B .=. 4.3V). Output is in
reset state at this time.
3. Output reset is released (RESET goes high) after a certain time (T_PR), from when CT starts charging until
discharge (the time from when CT voltage reaches a certain threshold value 1 (.=. 1.4V) until CT voltage
drops to a certain threshold value 2 (.=. 0.2V). Approximately 1A (V_CC=0.8V) of pull up current is output
from RESET.
Reset hold time : TPR is as follows.
TPR (mS) .=. 5000 CT (F)
CT charging starts again after reset release, and watchdog timer operation begins.
4. If a clock is input (negative edge trigger) to the CK pin during C_T charging, charging switches to discharge.
5. Discharge switches to charging when C_T voltage drops to a certain threshold value (.=. 0.2V). Steps 4 and 5
are repeated while a normal clock is input from the logic system.
6. Output goes to reset state (RESET goes low) when the clock ceases and C_T voltage reaches reset ON
threshold value (.=. 1.4V).
The formula for CT charging time (TWD: watchdog timer monitoring time) until reset is output is as follows.
T_WD (mS) .=. 500 C_T (F)
7. Watchdog timer reset time TWR is the discharge time until C_T voltage drops to reset OFF threshold value
(.=. 0.2V). The formula is as follows.
T_WR (mS) .=. 100 C_T (F)
After reset OFF threshold value is reached, output reset is released and C_T starts charging. Thereafter,
steps 4 and 5 are repeated if a normal clock is input, and when the clock ceases, 6 and 7 are repeated.
8. Reset of MM1095 is output when V_CC drops to V_SL (MM1095A .=. 3.2V, MM1095B .=. 4.2V). C_T is charged
simultaneously.
9. C_T charging starts when V_CC rises to VSH.
When Vcc drops momentarily, C_T charging begins after the charge is first discharged, if the time from V_CC
dropping below V_SL until it rises to V_SH is longer than the V_CC input pulse width standard value T_PI.
10.Output reset of MM1095 is released after V_CC goes above V_SH and after T_PR, and the watchdog timer starts. Thereafter,
8~10 are repeated when V_CC goes below V_SL.
11.When power of MM1095 is OFF, reset is output if VCC goes below VSL.
12.When V_CC drops to 0V, reset output is held until V_CC reaches 0.8V.