X9314.PDF

A PPLICATION N OTES

AVAILABLE

AN42 • AN44–50 • AN52 • AN53 • AN71 • AN73

Terminal Voltage

5V, 32 Taps, Log Taper

X9314

E 2 POT ™ Nonvolatile Digital Potentiometer

FEATURES

• Low Power CMOS

—V CC = 3V to 5.5V

—Active Current, 3mA Max

—Standby Current, 500

DESCRIPTION

The Xicor X9314 is a solid state nonvolatile potentiom-

eter and is ideal for digitally controlled resistance trim-

ming.

• 31 Resistive Elements

—Temperature Compensated

—

A Max

The X9314 is a resistor array composed of 31 resistive

elements. Between each element and at either end are

tap points accessible to the wiper element. The position of

the wiper element is controlled by the CS, U/D, and INC

inputs. The position of the wiper can be stored in nonvola-

tile memory and then be recalled upon a subsequent

power-up operation.

20% End to End Resistance Range

— –5V to +5V Range

• 32 Wiper Tap Points

—Wiper Positioned via Three-Wire Interface

—Similar to TTL Up/Down Counter

—Wiper Position Stored in Nonvolatile

Memory and Recalled on Power-Up

• 100 Year Wiper Position Data Retention

• X9314W = 10K W

• Packages

—8-Lead MSOP

—8-Lead PDIP

—8-Lead SOIC

All Xicor nonvolatile Digitally Controlled Potentiometers

are designed and tested for applications requiring ex-

tended endurance and data retention.

FUNCTIONAL DIAGRAM

U/D

INC

5-BIT

UP/DOWN

COUNTER

V H

5-BIT

NONVOLATILE

MEMORY

ONE

THIRTY-

TWO

DECODER

TRANSFER

GATES

RESISTOR

ARRAY

STORE AND

RECALL

CONTROL

CIRCUITRY

V CC

GND

V L

V W

6427 FHD F01

E 2 POT™ is a trademark of Xicor, Inc.

©Xicor, Inc. 1994, 1995, 1996 Patents Pending

Characteristics subject to change without notice

6427-1.7 6/12/96 T3/C1/D8 NS

X9314

X9314

PIN DESCRIPTIONS

PIN CONFIGURATION

V H and V L

The high (V H ) and low (V L ) terminals of the X9314

are equivalent to the fixed terminals of a mechanical

potentiometer. The minimum voltage is –5V and the

maximum is +5V. It should be noted that the terminology

of V L and V H references the relative position of the

terminal in relation to wiper movement direction

selected by the U/D input and not the voltage potential on

the terminal.

8-LEAD DIP/SOIC

INC

U/D

V H

V SS

X9314

V CC

V L

V W

8-LEAD MSOP

V W

Vw is the wiper terminal, equivalent to the movable

terminal of a mechanical potentiometer. The position

of the wiper within the array is determined by the

control inputs. The wiper terminal series resistance is

typically 40

V H

V SS

V W

V L

X9314

U/D

INC

V CC

6427 ILL F02.2

Up/Down (U/ D )

The U/D input controls the direction of the wiper move-

ment and whether the counter is incremented or

decremented.

PIN NAMES

Symbol

Description

V H

High Terminal

Increment ( INC )

The INC input is negative-edge triggered. Toggling INC

will move the wiper and either increment or decrement

the counter in the direction indicated by the logic level on

the U/D input.

V W

Wiper Terminal

V L

Low Terminal

V SS

Ground

V CC

Supply Voltage

U/D

Up/Down Input

Chip Select ( CS )

The device is selected when the CS input is LOW. The

current counter value is stored in nonvolatile memory

when CS is returned HIGH while the INC input is also

HIGH. After the store operation is complete the X9314

will be placed in the low power standby mode until the

device is selected once again.

INC

Increment Input

Chip Select Input

6427 PGM T01

Typical Attenuation Characteristics (dB)

-20

-40

-43.5

-60

TAP POSITION

6427 ILL F07

X9314

DEVICE OPERATION

Operation Notes

There are three sections of the X9314: the input control,

counter and decode section; the nonvolatile memory; and

the resistor array. The input control section operates just

like an up/down counter. The output of this counter is

decoded to turn on a single electronic switch connecting

a point on the resistor array to the wiper output. Under the

proper conditions the contents of the counter can be

stored in nonvolatile memory and retained for future use.

The resistor array is comprised of 31 individual resistors

connected in series. At either end of the array and

between each resistor is an electronic switch that

transfers the potential at that point to the wiper.

The system may select the X9314, move the wiper and

deselect the device without having to store the latest

wiper position in nonvolatile memory. The wiper

movement is performed as described above; once the

new position is reached, the system would keep the INC

LOW while taking CS HIGH. The new wiper position

would be maintained until changed by the system or

until a power-up/down cycle recalled the previously

stored data.

This would allow the system to always power-up to a

preset value stored in nonvolatile memory; then during

system operation minor adjustments could be made.

The adjustments might be based on user preference,

system parameter changes due to temperature drift,

etc...

The INC, U/D and CS inputs control the movement of the

wiper along the resistor array. With CS set LOW the

X9314 is selected and enabled to respond to the

U/D and INC inputs. HIGH to LOW transitions on INC will

increment or decrement (depending on the state of the

U/D input) a five bit counter. The output of this counter

is decoded to select one of thirty-two wiper positions

along the resistive array.

The state of U/D may be changed while CS remains

LOW. This allows the host system to enable the X9314

and then move the wiper up and down until the proper

trim is attained.

The wiper, when at either fixed terminal, acts like its

mechanical equivalent and does not move beyond the

last position. That is, the counter does not wrap around

when clocked to either extreme.

T IW /R TOTAL

The electronic switches on the X9314 operate in a

“make before break” mode when the wiper changes tap

positions. If the wiper is moved several positions mul-

tiple taps are connected to the wiper for t IW (INC to V W

change). The R TOTAL value for the device can tempo-

rarily be reduced by a significant amount if the wiper is

moved several positions.

The value of the counter is stored in nonvolatile memory

whenever CS transistions HIGH while the INC input is

also HIGH.

When the X9314 is powered-down, the last counter

position stored will be maintained in the nonvolatile

memory. When power is restored, the contents of the

memory are recalled and the counter is reset to the value

last stored.

R TOTAL with V CC Removed

The end to end resistance of the array will fluctuate once

V CC is removed.

SYMBOL TABLE

WAVEFORM

INPUTS

OUTPUTS

Must be

steady

Will be

steady

May change

from LOW

to HIGH

Will change

from LOW

to HIGH

May change

from HIGH

to LOW

Will change

from HIGH

to LOW

Don’t Care:

Changes

Allowed

Changing:

State Not

Known

N/A

Center Line

is High

Impedance

X9314

ABSOLUTE MAXIMUM RATINGS*

Temperature under Bias .................. –65

C to +135

*COMMENT

Stresses above those listed under “Absolute Maximum

Ratings” may cause permanent damage to the device.

This is a stress rating only and the functional operation

of the device at these or any other conditions above

those listed in the operational sections of this specifica-

tion is not implied. Exposure to absolute maximum

rating conditions for extended periods may affect device

reliability.

Storage Temperature ....................... –65

C to +150

Voltage on CS, INC, U/D and V CC

with Respect to V SS ............................... –1V to +7V

Voltage on V H and V L

Referenced to V SS ................................. –8V to +8V

Wiper Current .....................................................

1mA

ANALOG CHARACTERISTICS

Electrical Characteristics

End-to-End Resistance Tolerance .....................

20%

X9314W ..................................... +600 ppm/

C to +85

X9314W ...................................................... 10mW

Wiper Current ............................................

C Typical

Ratiometric Temperature Coefficient ............

20 ppm

1mA Max.

Typical Wiper Resistance ......................... 40

Wiper Adjustability

Unlimited Wiper Adjustment (Non-Store operation)

Wiper Position Store Operations ............. 100,000

Data Changes

at 1mA

Typical Noise .......................... < –120dB/ Hz Ref: 1V

Relative Variation

Relative variation is a measure of the error in step size

between taps = log(V w(n) ) – log(V w(n-1) ) = 0.07

0.003 for

Physical Characteristics

Marking Includes

Manufacturer’s Trademark

Resistance Value or Code

Date Code

tap n = 2 – 31

Typical Electrical Taper

100.0%

90.0%

80.0%

70.0%

60.0%

50.0%

40.0%

30.0%

20.0%

10.0%

0.0%

Tap

6427 ILL F06

V = |V H –V L |

X9314W .......................................................... 10V

Lead Temperature (Soldering 10 seconds) ....... 300

Temperature Coefficient

(–40

Power Rating at 25

X9314

RECOMMENDED OPERATING CONDITIONS

Temperature

Min.

Max.

Supply Voltage

Limits

Commercial

+70

X9314

10%

Industrial

–40

+85

X9314-3

3V to 5.5V

6427 PGM T04.1

Military

–55

+125

6427 PGM T03.1

D.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified.)

Limits

Symbol

Parameter

Min.

Typ. (4)

Max. Units

Test Conditions

I CC

V CC Active Current

CS = V IL , U/D = V IL or V IH and

INC = 0.4V/2.4V @ max. t CYC

I SB

Standby Supply Current

500

CS = V CC – 0.3V, U/D and INC =

V SS or V CC – 0.3V

I LI

CS, INC, U/D Input

A IN = V SS to V CC

Leakage Current

V IH

CS, INC, U/D Input

V CC + 1

HIGH Voltage

V IL

CS, INC, U/D Input

–1

0.8

LOW Voltage

R W

Wiper Resistance

100

Max. Wiper Current

1mA

V VH

VH Terminal Voltage

–5

V VL

VL Terminal Voltage

–5

C IN (5) CS, INC, U/D Input

V CC = 5V, V IN = V SS ,

Capacitance

T A = 25

C, f = 1MHz

6427 PGM T05.3

STANDARD PARTS

Part Number

Maximum Resistance

Wiper Increments

Minimum Resistance

X9314W

10K

Log Taper

W 6427 PGM T08.1

Notes: (4) Typical values are for T A = 25 ° C and nominal supply voltage.

(5) This parameter is periodically sampled and not 100% tested.

Test Circuit #1

Test Circuit #2

V H

TEST POINT

V W

FORCE

CURRENT

V L

6427 ILL F04

6427 ILL F05

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