CAT5401

Doc. No. MD-2012 Rev. J

2

© 2009 SCILLC. All rights reserved.

Characteristics subject to change without notice

PIN DESCRIPTIONS

SI: Serial Input

SI is the serial data input pin. This pin is used to input all

opcodes, byte addresses and data to be written to the

CAT5401. Input data is latched on the rising edge of the

serial clock.

SO: Serial Output

SO is the serial data output pin. This pin is used to

transfer data out of the CAT5401. During a read cycle,

data is shifted out on the falling edge of the serial

clock.

SCK: Serial Clock

SCK is the serial clock pin. This pin is used to

synchronize

the

communication

between

the

microcontroller and the CAT5401. Opcodes, byte

addresses or data present on the SI pin are latched on

the rising edge of the SCK. Data on the SO pin is

updated on the falling edge of the SCK.

A0, A1: Device Address Inputs

These inputs set the device address when addressing

multiple devices. A total of four devices can be

addressed on a single bus. A match in the slave

address must be made with the address input in order

to initiate communication with the CAT5401.

terminal connections on a mechanical potentiometer.

a mechanical potentiometer.

CS

¯¯¯: Chip Select

CS

¯¯¯ is the Chip select pin. CS

¯¯¯ low enables the

CAT5401 and CS

¯¯¯ high disables the CAT5401. CS

¯¯¯

high takes the SO output pin to high impedance and

forces the devices into a Standby mode (unless an

internal write operation is underway). The CAT5401

draws ZERO current in the Standby mode. A high to

low transition on CS

¯¯¯ is required prior to any sequence

being initiated. A low to high transition on CS

¯¯¯ after a

valid write sequence is what initiates an internal write

cycle.

WP

¯¯¯: Write Protect

WP

¯¯¯ is the Write Protect pin. The Write Protect pin will allow normal read/write operations when held high. When

WP

¯¯¯ is tied low, all non-volatile write operations to the Data registers are inhibited (change of wiper control register

is allowed). WP

¯¯¯ going low while CS

¯¯¯ is still low will interrupt a write to the registers. If the internal write cycle has

already been initiated, WP

¯¯¯ going low will have no effect on any write operation.

HOLD

¯¯¯¯¯: Hold

The HOLD

¯¯¯¯¯ pin is used to pause transmission to the CAT5401 while in the middle of a serial sequence without

having to retransmit entire sequence at a later time. To pause, HOLD

¯¯¯¯¯ must be brought low while SCK is low. The

SO pin is in a high impedance state during the time the part is paused, and transitions on the SI pins will be

ignored. To resume communication, HOLD

¯¯¯¯¯ is brought high, while SCK is low. (HOLD

¯¯¯¯¯ should be held high any

time this function is not being used.) HOLD

Pin#

(SOIC)

Pin#

(TSSOP) Name Function

1

19

Supply Voltage

2

20

Low Reference Terminal

for Potentiometer 0

3

21

High Reference Terminal

for Potentiometer 0

4

22

Wiper Terminal for

Potentiometer 0

5

23

CS

¯¯¯

Chip Select

6

24

WP

¯¯¯

Write Protection

7

1

SI

Serial Input

8

2

A1

Device Address

9

3

Low Reference Terminal

for Potentiometer 1

10

4

High Reference Terminal

for Potentiometer 1

11

5

Wiper Terminal for

Potentiometer 1

12

6

GND

Ground

13

7

NC

No Connect

14

8

Wiper Terminal for

Potentiometer 2

15

9

High Reference Terminal

for Potentiometer 2

16

10

Low Reference Terminal

for Potentiometer 2

17

11

SCK

Bus Serial Clock

18

12

HOLD

19

13

SO

Serial Data Output

20

14

A0

Device Address, LSB

21

15

Wiper Terminal for

Potentiometer 3

22

16

High Reference Terminal

for Potentiometer 3

23

17

Low Reference Terminal

for Potentiometer 3

24

18

NC

No Connect