CAT5259
http://onsemi.com
3
PIN DESCRIPTIONS
Table 1. PIN DESCRIPTIONS
Pin # Name Function
1 NC No Connect
2 A0 Device Address, LSB
3 R
W3
Wiper Terminal for Potentiometer 3
4 R
H3
High Reference Terminal for
Potentiometer 3
5 R
L3
Low Reference Terminal for Potentiometer 3
6 NC No Connect
7 V
CC
Supply Voltage
8 R
L0
Low Reference Terminal for Potentiometer 0
9 R
H0
High Reference Terminal for
Potentiometer 0
10 R
W0
Wiper Terminal for Potentiometer 0
11 A2 Device Address
12 WP Write Protection
13 SDA Serial Data Input/Output
14 A1 Device Address
15 R
L1
Low Reference Terminal for Potentiometer 1
16 R
H1
High Reference Terminal for
Potentiometer 1
17 R
W1
Wiper Terminal for Potentiometer 1
18 GND Ground
19 NC No Connect
20 R
W2
Wiper Terminal for Potentiometer 2
21 R
H2
High Reference Terminal for
Potentiometer 2
22 R
L2
Low Reference Terminal for Potentiometer 2
23 SCL Bus Serial Clock
24 A3 Device Address
SCL: Serial Clock
The CAT5259 serial clock input pin is used to clock all
data transfers into or out of the device.
SDA: Serial Data
The CAT5259 bidirectional serial data pin is used to
transfer data into and out of the device. The SDA pin is an
open drain output and can be wire-Ored with the other open
drain or open collector I/Os.
A0, A1, A2, A3: Device Address Inputs
These inputs set the device address when addressing
multiple devices. A total of sixteen 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 CAT5259.
R
H
, R
L
: Resistor End Points
The four sets of R
H
and R
L
pins are equivalent to the
terminal connections on a mechanical potentiometer.
R
W
: Wiper
The four R
W
pins are equivalent to the wiper terminal of
a mechanical potentiometer.
WP
: Write Protect Input
The WP
pin when tied low prevents non-volatile writes to
the device (change of wiper control register is allowed) and
when tied high or left floating normal read/write operations
are allowed. See Write Protection on page 7 for more details.
DEVICE OPERATION
The CAT5259 is four resistor arrays integrated with a I
2
C
serial interface logic, four 8-bit wiper control registers and
sixteen 8-bit, non-volatile memory data registers. Each
resistor array contains 255 separate resistive elements
connected in series. The physical ends of each array are
equivalent to the fixed terminals of a mechanical
potentiometer (R
H
and R
L
). The tap positions between and
at the ends of the series resistors are connected to the output
wiper terminals (R
W
) by a CMOS transistor switch. Only
one tap point for each potentiometer is connected to its wiper
terminal at a time and is determined by the value of the wiper
control register. Data can be read or written to the wiper
control registers or the non-volatile memory data registers
via the I
2
C bus. Additional instructions allow data to be
transferred between the wiper control registers and each
respective potentiometer’s non-volatile data registers. Also,
the device can be instructed to operate in an “increment/
decrement” mode.
