LOW POWER 2 OUTPUT SYSTEM RESET IC SERIES
In general,the memory backup function of
a microcomputer,as shown in figure,uses two diodes to switch
between main power supply and backup power supply.The
M62001~M62008 are ICs that,in such memory backup
operation,monitor in 2 steps each voltage on the VDD line.
The ICs have an intelligent sequence such as substantial
hysteresis action of RESET toward normal state at restoration of
supply voltage,as well as 2-step detection in low power
OPERATION IN DETAIL
1.Two Step Detection
The ICs perform 2-step detection of supply voltage and have 2
output pins (INT and RESET).Although they have 2 comparators
for 2-step detection,they differ significantly from such that are
simply provided with independent detectors,because the RESET
output signal is dependent at power-up and the like upon the
INT output signal.
3.RESET Output (Detection of 2.15V)
The RESET outputs a signal to prevent the microcomputer from
malfunctioning due to a drop in supply voltage.
When powering up,RESET is kept at low level until the supply
voltage reaches VSH.If the supply voltage rises to VSH,RESET
is set to high level.By inserting a capacitor between the Cd pin
and GND,it is possible to produce a desired delay time (td).To
set a delay time,equation below is used.
Once the supply voltage has exceeded VSH and the RESET
output is set to high level,RESET maintains the high level until
the supply voltage drops to VBATT.When the supply voltage
drops to VBATT,RESET goes low thereby resetting and
initializing the microcomputer.
The RESET output has a large hysteresis voltage of
approximately 2V between the rise in supply voltage at power-
up and its fall.
RESET OUTPUT VOLTAGE VS.
2.INT output (Detection of 4.45V and 4.25V)
The INT output at the power-up of supply voltage detects VSH
(4.45V/4.25V)to inform the microcomputer system of the fact
that the supply voltage has reached its normal level.When the
supply voltage drops from its normal level to
VSL(4.45V/4.25V)an interruption signal is output to alter the
microcomputer system into RAM backup mode. The
microcomputer at this point enters sleep state and secures
memory by a stop command issued by the interruption
signal.These detection voltage ,VSH the rise,and VSL the fall,of
supply voltage,have a 100-mV hysteresis voltage between
themselves. VSH-VSL.=. 100(mV)
23 4 5
SUPPLY VOLTAGE Vcc
INT OUTPUT VOLTAGE VS.
4.0 4.2 4.4 4.6 4.8 5.0
SUPPLY VOLTAGE Vcc(V)
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