BQ4802LYPW Datasheet, PDF (5/26 Pages) Texas Instruments – PARALLEL REAL-TIME CLOCK WITH CPU SUPERVISOR AND EXTERNAL SRAM NONVOLATILE MEMORY BACKUP

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PIN ASSIGNMENTS
bq4802Y
bq4802LY
SLUS464C – AUGUST 2000 – REVISED JUNE 2002
V_OUT
X1
X2
WDO
INT
RST
A3
A2
A1
A0
DQ0
DQ1
DQ2
V_SS
DW OR PW PACKAGE
(TOP VIEW)
1
28
2
27
3
26
4
25
5
24
6
23
7
22
8
21
9
20
10
19
11
18
12
17
13
16
14
15
V_CC
WE
CE_IN
CE_OUT
BC
WDI
OE
CS
V_SS
DQ7
DQ6
DQ5
DQ4
DQ3
DSH PACKAGE
(TOP VIEW)
V_OUT
NC
NC
WDO
INT
RST
A3
A2
A1
A0
DQ0
DQ1
DQ2
V_SS
1
28
2
27
3
26
4
25
5
24
6
23
7
22
8
21
9
20
10
19
11
18
12
17
13
16
14
15
NC – No internal connection
V_CC
WE
CE_IN
CE_OUT
NC
WDI
OE
CS
NC
DQ7
DQ6
DQ5
DQ4
DQ3
Terminal Functions
TERMINAL
I/O
NAME
NO.
DESCRIPTION
A0
10
A0 – A3 allow access to the 16 bytes of real-time clock and control registers.
A1
9
A2
8
A3
7
BC
24(1)
BC should be connected to a 3-V backup cell. A voltage within the VBC range on the BC pin should be present
upon power up to provide proper oscillator start-up. Not accessible in module packages.
CEIN
26
CEOUT 25
CS
21
Input to the chip-enable gating circuit
CEOUT goes low only when CEIN is low and VCC is above the power fail threshold. If CEIN is low, and power fail
occurs, CEOUT stays low for 100 µs or until CEIN goes high, whichever occurs first.
I Chip-select input
DQ0
11
I DQ0–DQ7 provide x8 data for real-time clock information. These pins connect to the memory data bus.
DQ1
12
I
DQ2
13
I
DQ3
15
I
DQ4
16
I
DQ5
17
I
DQ6
18
I
DQ7
19
I
INT
5
INT goes low when a power fail, periodic, or alarm condition occurs. INT is an open-drain output.
OE
22
OE provides the read control for the RTC memory locations.
RST
6
RST goes low whenever VCC falls below the power fail threshold. RST remains low for 200 ms (typical) after
VCC crosses the threshold on power-up. The bq4802Y/bq4802LY also enters the reset cycle when RST is released
from being pulled low for more than 1 µs.
VCC
28
I 5-V or 3.3-V input
VOUT
1
O VOUT provides the higher of VCC or VBC, switched internally, to supply external RAM.
VSS
14
20(1)
Ground
(1) _{This pin should be left unconnected (NC) when using the SNAPHAT (DSH) package.}
5