bq4802Y

bq4802LY

SLUS464C – AUGUST 2000 – REVISED JUNE 2002

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5

PIN ASSIGNMENTS

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

X1

X2

WDO

INT

RST

A3

A2

A1

A0

DQ0

DQ1

DQ2

WE

BC

WDI

OE

CS

DQ7

DQ6

DQ5

DQ4

DQ3

DW OR PW PACKAGE

(TOP VIEW)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

NC

NC

WDO

INT

RST

A3

A2

A1

A0

DQ0

DQ1

DQ2

WE

NC

WDI

OE

CS

NC

DQ7

DQ6

DQ5

DQ4

DQ3

DSH PACKAGE

(TOP VIEW)

NC – No internal connection

Terminal Functions

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

A0

10

A0 – A3 allow access to the 16 bytes of real-time clock and control registers.

A1

9

yg

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

Input to the chip-enable gating circuit

CEOUT

25

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.

CS

21

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

Q

Q

y

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.

V

14

Ground

VSS

20(1)

(1) This pin should be left unconnected (NC) when using the SNAPHAT (DSH) package.