CAT5251 Datasheet, PDF (2/15 Pages) Catalyst Semiconductor – Quad Digitally Programmable Potentiometer (DPP) with 256 Taps and SPI Interface

CAT5251
PIN DESCRIPTION
PIN DESCRIPTIONS
Pin
(SOIC/TSSOP)
1
2
3
4
Name
SO
A0
RW3
RH3
5
RL3
6
NC
7
VCC
8
RL0
9
RH0
10
RW0
11
CS
12
WP
13
SI
14
A1
15
RL1
16
RH1
17
RW1
18
GND
19
NC
20
RW2
21
RH2
22
RL2
23
SCK
24
HOLD
Function
Serial Data Output
Device Address, LSB
Wiper Terminal for Potentiometer 3
High Reference Terminal
for Potentiometer 3
Low Reference Terminal
for Potentiometer 3
No Connect
Supply Voltage
Low Reference Terminal
for Potentiometer 0
High Reference Terminal
for Potentiometer 0
Wiper Terminal for Potentiometer 0
Chip Select
Write Protection
Serial Input
Device Address
Low Reference Terminal
for Potentiometer 1
High Reference Terminal
for Potentiometer 1
Wiper Terminal for Potentiometer 1
Ground
No Connect
Wiper Terminal for
Potentiometer 2
High Reference Terminal
for Potentiometer 2
Low Reference Terminal
for Potentiometer 2
Bus Serial Clock
Hold
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 CAT5251. 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 CAT5251. 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 CAT5251. 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 address-
ing 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 CAT5251.
RH, RL: Resistor End Points
The four sets of RH and RL pins are equivalent to the
terminal connections on a mechanical potentiometer.
RW: Wiper
The four RW pins are equivalent to the wiper terminal
of a mechanical potentiometer.
CS: Chip Select
CS is the Chip select pin. CS low enables the
CAT5251 and CS high disables the CAT5251. 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 CAT5251
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 CAT5251 while in the middle of a serial sequence without having to re-
transmit entire sequence at a later time. To pause, HOLD must be brought low while SCK is low. The SO pin is in a high imped-
ance 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 may be tied high
directly to VCC or tied to VCC through a resistor.
Document No. 2017, Rev. D
2