BQ4845 Datasheet, PDF (2/22 Pages) Texas Instruments – Parallel RTC With CPU Supervisor

bq4845/bq4845Y
Functional Description
Figure 1 is a block diagram of the bq4845. The follow-
ing sections describe the bq4845 functional operation
including clock interface, data-retention modes,
power-on reset timing, watchdog timer activation, and
interrupt generation.
Figure 1. Block Diagram
Truth Table
VCC
CS
OE
WE
CEOUT VOUT
Mode
DQ
Power
< VCC (max.)
VIH
X
X
CEIN VOUT1 Deselect High Z
Standby
VIL
X
VIL
CEIN V_OUT1
Write
DIN
Active
> VCC (min.)
VIL
VIL
VIH
CEIN V_OUT1
Read
DOUT
Active
VIL
VIH
VIH
CEIN V_OUT1
Read High Z
Active
< VPFD (min.) > VSO
X
X
X
VOH VOUT1 Deselect High Z
CMOS standby
≤ VSO
X
X
X
VOHB VOUT2 Deselect High Z Battery-backup mode
Aug. 1995
2