mb3790pf Fujitsu Microelectronics, Inc., mb3790pf Datasheet - Page 6

• Manufacturer Part Number: mb3790pf
• Description: Battery Backup Ic
• Manufacturer: Fujitsu Microelectronics, Inc.

6
MB3790
1. Operation When the Input Voltage Goes On or Off
(1) Power-on
While the power supply voltage is less than V
are in the standby mode with the power supplied by the battery.
When the power supply voltage rises to a level greater than or equal to V
output pins turns on and the power for such devices is supplied from the V
battery voltage detection and the secondary battery recharging operations are actuated.
(2) Standby mode
When the power supply voltage rises to a level greater than or equal to V
for the set duration of time and the devices such as SRAM or a microprocessor are held in the standby mode. Note
that the set duration of time can be adjusted by changing the capacitance of the C
The RESET pin outputs an inverted signal of the RESET pin.
(3) Active mode
The reset signal is cleared and the devices such as SRAM or a microprocessor are placed in the operating mode.
DESCRIPTION OF OPERATION
RESET
RESET
V
V
OUT
IN
(1)
High level
Low level
t
(2)
PO
High level
Low level
INH
(3)
(4.3 V Typ), the protected devices such as SRAM or a microprocessor
High level
(4)
Low level
t
(2)
PO
Low level
High level
(3)
INH
, the PMOS transistor between the input/
INH
, the RESET pin outputs a High level
IN
pin. At the same time, the primary
High level
Low level
DV
T
(4)
pin.
IN
V
V
V
V
V
V
V
INH
INL
IN
BAT1
IN
BAT1
IN
-DV
-DV
-DV
-DV
-DV
1
1
1
B1
B1