M62021L/P/FP
System Reset IC with Switch for Memory Backup
REJ03D0784-0200
Rev.2.00
Jun 15, 2007
Description
The M62021 is a system IC that controls the memory backup function of microcomputer (internal RAM).
The IC outputs reset signals (RES/RES) to a microcomputer at power-down and power failure. It also shifts the power
supply to RAM from main to backup, outputs a signal (CS) that invokes standby mode, and alters RAM to backup
circuit mode.
The M62021 contains, in a single chip, power supply monitor and RAM backup functions needed for a microcomputer
system, so that the IC makes it possible to construct a system easily and with fewer components compared with a
conventional case that uses individual ICs and discrete components.
Features
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Built-in switch for selection between main power supply and backup power supply to RAM.
Small difference between input and output voltage (IOUT = 80 mA, VIN = 5 V) 0.2 V Typ
Detection voltage (power supply monitor voltage) 4.40 V ± 0.2 V
Chip select signal output (CS)
Two channels of reset outputs (RES/RES)
Power on reset circuit built-in
Delay time variable by an external capacitance connected to Ct pin
Facilitates to form backup function with a few number of components
Application
• Power supply control systems for memory backup of microcomputer system and SRAM boards with built-in backup
function that require switching between external power supply and battery.
Block Diagram
SW
1 VOUT
VIN 3
R1
–
R2
+
D1
Com
Reset
circuit
2 VBAT
1.24V
8 CS
RES 7
Delay
circuit
RES 5
6
GND
REJ03D0784-0200 Rev.2.00 Jun 15, 2007
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4 Ct
