Doc. No. 2002, Rev. F

CAT5112

32-Tap Digitally Programmable Potentiometer (DPPTM) with Buffered Wiper

FEATURES

32-position linear taper potentiometer

Non-volatile NVRAM wiper storage;
buffered wiper

Low power CMOS technology

Single supply operation: 2.5V-6.0V

Increment up/down serial interface

Resistance values: 10k

50k

and 100k

Available in PDIP, SOIC, TSSOP and MSOP packages

APPLICATIONS

Automated product calibration

Remote control adjustments

Offset, gain and zero control

Tamper-proof calibrations

Contrast, brightness and volume controls

Motor controls and feedback systems

Programmable analog functions

power is returned. The wiper can be adjusted to test new
system values without effecting the stored
setting. Wiper-control of the CAT5112 is
accomplished with three input control pins,

, U/

and

INC

. The

INC

input increments the wiper in the

direction which is determined by the logic state of
the U/

input. The

input is used to select the

device and also store the wiper position prior to
power down.

The digitally programmable potentiometer can be
used as a three-terminal resistive divider or as a
two-terminal variable resistor. DPPs bring variability and
programmability to a broad range of applications
and are used primarily to control, regulate or adjust a
characteristic or parameter of an analog circuit.

FUNCTIONAL DIAGRAM

DESCRIPTION

The CAT5112 is a single digitally programmable
potentiometer (DPPTM) designed as a electronic
replacement for mechanical potentiometers and trim
pots. Ideal for automated adjustments on high volume
production lines, they are also well suited for
applications where equipment requiring periodic
adjustment is either difficult to access or located in a
hazardous or remote environment.

The CAT5112 contains a 32-tap series resistor array
connected between two terminals R

and R

. An up/

down counter and decoder that are controlled by three
input pins, determines which tap is connected to the
wiper, R

. The CAT5112 wiper is buffered by an op

amp that operates rail to rail. The wiper setting, stored in
non-volatile NVRAM memory, is not lost when the de-
vice is powered down and is automatically recalled when

Electronic Potentiometer

Implementation

RWB

INC

Control

and

Memory

Power On Recall

CAT5112

Doc. No. 2002, Rev. F

of the CAT5112 and is active low. When in a high
state, activity on the

INC

and U/

inputs will not

affect or change the position of the wiper.

DEVICE OPERATION

The CAT5112 operates like a digitally controlled
potentiometer with R

and R

equivalent to the high

and low terminals and R

equivalent to the mechanical

potentiometer's wiper. There are 32 available tap posi-
tions including the resistor end points, R

and R

. There

are 31 resistor elements connected in series between
the R

and R

terminals. The wiper terminal is

connected to one of the 32 taps and controlled by three
inputs,

INC

, U/

and

. These inputs control a five-bit

up/down counter whose output is decoded to select the
wiper position. The selected wiper position can be
stored in nonvolatile memory using the

INC

and

inputs.

With

set LOW the CAT5112 is selected and will

respond to the U/

and

INC

inputs. HIGH to LOW

transitions on

INC

wil increment or decrement the

wiper (depending on the state of the U/

input and five-

bit counter). The wiper, when at either fixed terminal,
acts like its mechanical equivalent and does not move
beyond the last position. The value of the counter is
stored in nonvolatile memory whenever

transitions

HIGH while the

INC

input is also HIGH. When the

CAT5112 is powered-down, the last stored wiper counter
position is maintained in the nonvolatile memory. When
power is restored, the contents of the memory are
recalled and the counter is set to the value stored.

With

INC

set low, the CAT5112 may be de-selected

and powered down without storing the current wiper
position in nonvolatile memory. This allows the
system to always power up to a preset value stored
in nonvolatile memory.

PIN DESCRIPTIONS

INC

: Increment Control Input

The

INC

input (on the falling edge) moves the wiper in the

up or down direction determined by the condition of the
U/

input.

: Up/Down Control Input

The U/

input controls the direction of the wiper

movement. When in a high state and

is low, any high-

to-low transition on

INC

will cause the wiper to move one

increment toward the R

terminal. When in a low state

and

is low, any high-to-low transition on

INC

will

cause the wiper to move one increment towards the
R

terminal.

High End Potentiometer Terminal

is the high end terminal of the potentiometer. It is not

required that this terminal be connected to a potential
greater than the R

terminal. Voltage applied to the R

terminal cannot exceed the supply voltage, V

or go

below ground, GND.

: Wiper Potentiometer Terminal (Buffered)

is the buffered wiper terminal of the potentiometer. Its

position on the resistor array is controlled by the control
inputs,

INC

, U/

and

: Low End Potentiometer Terminal

is the low end terminal of the potentiometer. It is not

required that this terminal be connected to a potential
less than the R

terminal. Voltage applied to the R

terminal cannot exceed the supply voltage, V

or go

below ground, GND. R

and R

are electrically

interchangeable.

: Chip Select

The chip select input is used to activate the control input

PIN FUNCTIONS

Pin Name

Function

INC

Increment Control

Up/Down Control

Potentiometer High Terminal

GND

Ground

Buffered Wiper Terminal

Potentiometer Low Terminal

Chip Select

Supply Voltage

PIN CONFIGURATION

PDIP/SOIC Package

TSSOP Package

MSOP Package

INC

RL
RWB

GND

1
2
3
4

8
7
6
5

INC

RL
RWB

GND

RWB

GND

INC

CAT5112

Doc. No. 2002, Rev. F

OPERATING MODES

ABSOLUTE MAXIMUM RATINGS

Supply Voltage

to GND

-0.5V to +7V

Inputs

to GND

-0.5V to V

+0.5V

INC

to GND

-0.5V to V

+0.5V

to GND

-0.5V to V

+0.5V

to GND

-0.5V to V

+0.5V

to GND

-0.5V to V

+0.5V

to GND

-0.5V to V

+0.5V

Operating Ambient Temperature

Commercial (`C' or Blank suffix)

C to +70

Industrial (`I' suffix)

-40

C to +85

Junction Temperature

+150

Storage Temperature

-65

C to +150

Lead Soldering (10 sec max)

+300

* Stresses above those listed under Absolute Maximum Ratings may
cause permanent damage to the device. Absolute Maximum Ratings
are limited values applied individually while other parameters are
within specified operating conditions, and functional operation at any
of these conditions is NOT implied. Device performance and reliability
may be impaired by exposure to absolute rating conditions for extended
periods of time.

NOTES:

(1) This parameter is tested initially and after a design or process change that affects the parameter.
(2) Latch-up protection is provided for stresses up to 100mA on address and data pins from 1V to V

+ 1V

(3) I

=source or sink

(4) These parameters are periodically sampled and are not 100% tested.

Potentiometer
Equivalent Circuit

INC

U/D

Operation

High to Low

Low

High

Wiper toward H

High to Low

Low

Wiper toward L

High

Low to High

Store Wiper Position

Low

Low to High

No Store, Return to Standby

High

Standby

RELIABILITY CHARACTERISTICS

Symbol

Parameter

Test Method

Min

Typ

Max

Units

ZAP

(1)

ESD Susceptibility

MIL-STD-883, Test Method 3015

2000

Volts

LTH

(1)(2)

Latch-Up

JEDEC Standard 17

100

Data Retention

MIL-STD-883, Test Method 1008

100

Years

END

Endurance

MIL-STD-883, Test Method 1003

1,000,000

Stores

Power Supply

Symbol

Parameter

Conditions

Min

Typ

Max

Units

Operating Voltage Range

2.5

6.0

CC1

Supply Current (Increment)

= 6V, f = 1MHz, I

200

= 6V, f = 250kHz, I

100

CC2

Supply Current (Write)

Programming, V

= 6V

= 3V

500

ISB

(2)

Supply Current (Standby)

CS=V

-0.3V

150

U/D, INC=V

-0.3V or GND

DC Electrical Characteristics: V

= +2.5V to +6.0V unless otherwise specified

Symbol

Parameter

Conditions

Min

Typ

Max

Units

Input Leakage Current

= V

Input Leakage Current

= 0V

IH1

TTL High Level Input Voltage

4.5V

5.5V

IL1

TTL Low Level Input Voltage

0.8

IH2

CMOS High Level Input Voltage

2.5V

x 0.7

+ 0.3

IL2

CMOS Low Level Input Voltage

-0.3

x 0.2

Logic Inputs

CAT5112

Doc. No. 2002, Rev. F

Symbol

Parameter

Conditions

Min

Typ

Max

Units

POT

Potentiometer Resistance

-10 Device

-50 Device

-00 Device

100

Pot Resistance Tolerance

Voltage on R

Resolution

INL

Integral Linearity Error

0.5

LSB

DNL

Differential Linearity Error

0.25 0.5

LSB

OUT

Buffer Output Resistance

.05V

.95V

, V

=5V

OUT

Buffer Output Current

.05V

.95V

, V

=5V

RPOT

TC of Pot Resistance

300

ppm/°C

RATIO

Ratiometric TC

TBD

ppm/°C

ISO

Isolation Resistance

TBD

Potentiometer Capacitances

8/8/25

Frequency Response

Passive Attenuator, 10k

1.7

MHz

WB(SWING)

Output Voltage Range

OUT

100

A, V

=5V

0.01V

.99V

Potentiometer Parameters

CAT5112

Doc. No. 2002, Rev. F

Range

2.5V

Input Pulse Levels

0.2V

to 0.7V

Input Rise and Fall Times

10ns

Input Reference Levels

0.5V

AC CONDITIONS OF TEST

A. C. TIMING

(1) Typical values are for T

=25°C and nominal supply voltage.

(2) This parameter is periodically sampled and not 100% tested.
(3) MI in the A.C. Timing diagram refers to the minimum incremental change in the W output due to a change in the wiper position.

INC

CYC

(3)

90%

10%

(store)

tID

tDI

CPH

Symbol

Parameter

Min

Typ

(1)

Max

Units

to INC Setup

100

INC

Setup

INC

Hold

100

INC

LOW Period

250

INC

HIGH Period

250

INC

Inactive to

Inactive

CPH

Deselect Time (NO STORE)

100

CPH

Deselect Time (STORE)

INC

to V

OUT

Change

CYC

INC

Cycle Time

(2)

INC

Input Rise and Fall Time

500

(2)

Power-up to Wiper Stable

msec

Store Cycle

AC OPERATING CHARACTERISTICS:
V

= +2.5V to +6.0V, V

= V

, V

= 0V

, unless otherwise specified

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