MM1099

Features:

` Built-in watch dog timer
` Low current consumption 130A TYP.
` Low operating threshold voltage VCC=0.8V
` Watch dog stop function (RCT terminal)
` Long clock monitoring time TPR (POWER ON) : TWD (clock monitoring)=1 : 1
` Fewer outer components

Application

· Reset circuit for microcomputers, CPU and MPU.
· Reset circuit for logic circuitry.
· Monitoring of microcomputer system, etc.

Pinout




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	300	mW
Storage temperature	TSTG	-40~+125

Description

` The RESET will become "Low" if V<sub>CC</sub> rises to about 0.8V. Approximately 1A (Vcc=0.8V) of pull up current is output from RESET
` Charging starts at the capacitor C_T when V_CC riset to V_SH (MM1099A .=. 3.25V, MM1099B .=. 4.3V), when the output has been reset.
` The output reset is released after a given interval T<sub>PR</sub> from when the C<sub>T</sub> Starts charging and to when it discharges (that is, the time from when C<sub>T</sub> voltage takes a given value 1 (.=. 1.4V) up until decreases to a given value 2 (.=. 0.2V). (RESET will become "High"). The RESET will output a pull up current, about 1A (VCC=0.8V). The reset hold time TPR is expressed by the following formula: T<sub>PR</sub> (ms) .=. 5000 C<sub>T</sub> (F) After the reset release C<sub>T</sub> restarts charging and the watch dog timer begins operating. Note that input of clock while POWER ON RESET time T<sub>PR</sub> will cause an erroneous operation.
` If clock is input into CK terminal while C_T is charging (negative edge trigger), C_T changes from charging over to discharging.
` When the C<sub>T</sub> voltage decreases to a given threshold (.=. 0.2V), then discharging changes over to charging. Steps 4 and 5 will be repeated while normal clock is input from the logic system.
` When the clock ceases and CT voltage reaches the RESET ON threshold (.=. 1.4V), the output enters into
reset state (RESET becoming "Low"). The C_T charging time T_WD up until the reset is output (watch dog monitoring time) is expressed by the
following formula: T_WD (ms) .=. 5000 * CT (F)
` The reset time at the time of watch dog time TWR is the discharging time while the CT voltage lowers down to the reset off threshold (.=. 0.2V). The calculation formula: T<sub>WR</sub> (ms) .=. 100 * C<sub>T</sub> (F)
After the reset off threshold is reached, the output reset is released and C<sub>T</sub> commences to charge. If thenceforth the clock is input normally, steps 4 and 5  will be repeated, and setps 6 and 7 repeated if theclock ceases.
` When V_CC lowers down to V_SL (MM1099A .=. 3.2V, MM1099B .=. 4.2V), the reset is output. At the same time C_T charged.
` C<sub>T</sub> discharging of MM1099 starts when V<sub>CC</sub> rises up to V<sub>SH</sub>.
If V<sub>CC</sub> lower instantaneously, charging starts after load discharging of C<sub>T</sub> if the time interval from when V<sub>CC</sub> comes lower than V<sub>SL</sub> up until when it rises to V<sub>SH</sub> or higher is equal or superior to the reference value of V<sub>CC</sub> input pulse width T<sub>PI</sub>.
` The output reset of MM1099 is released T_PR after V_CC becomes VSH or higher, and the watch dog time will start. Then if V_CC becomes V_SL or lower, steps 8 to 10 will be repeated.
` If power Off occurs, reset is output if V<sub>CC</sub> becomes V<sub>SL</sub> or lower.
` When V_CC of MM1099 comes down to 0V, the reset output will hold up until V_CC becomes 0.8V.