XICOR X9315WS-2,7, X9315WS, X9315WPI-2,7, X9315WPI, X9315WP-2,7 Datasheet

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XICOR X9315WS-2,7, X9315WS, X9315WPI-2,7, X9315WPI, X9315WP-2,7 Datasheet

APPLICATION NOTE

A V A I L A B L E

AN104

Low Noise, Low Power, 32 Taps

X9315

E2POTTM Nonvolatile Digital Potentiometer

FEATURES

Low Power CMOS

VCC = 2.7V to 5.5V, Single Supply

Active Current, 50µA (Increment) max

Active Current, 400µA (Store) Max

Standby Current, 1µA Max

Low Noise

31 Resistive Elements

Temperature Compensated

± 20% End to End Resistance Range

VSS to VCC 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

X9315Z = 1KΩ

X9315W = 10KΩ

Packages

8-Lead SOIC

8-Lead MSOP

8-Pin DIP

DESCRIPTION

The Xicor X9315 is a solid state "micropower" nonvolatile potentiometer and is ideal for digitally controlled resistance trimming.

The X9315 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 posi- tion of the wiper element is controlled by the CS, U/D, and INC inputs. The position of the wiper can be stored in nonvolatile memory and then be recalled upon a subsequent power-up operation.

The resolution of the X9315 is equal to the maximum resistance value divided by 31. As an example, for the X9315W (10KΩ) each tap point represents 323Ω.

All Xicor nonvolatile digital potentiometers are designed and tested for applications requiring extended endurance and data retention.

FUNCTIONAL DIAGRAM

U/D

5-BIT

CMOS SWITCH

VH

INC

UP/DOWN

 

 

 

CS

COUNTER

 

 

5-BIT

ONE

 

OF

 

NONVOLATILE

 

THIRTY-

 

MEMORY

 

TWO

 

 

RESISTOR

 

WIPER

 

ARRAY

 

POSITION

 

 

 

DECODER

 

STOREAND

 

 

RECALL

 

 

CONTROL

 

 

CIRCUITRY

 

 

VL

VW

6732 FM1

E2POT™ is a trademark of Xicor, Inc.

6732-2.0 5/30/97 T1/C0/D0 SH

1

Characteristics subject to change without notice

 

 

X9315

PIN DESCRIPTIONS

VH and VL

The high (VH) and low (VL) terminals of the X9315 are equivalent to the fixed terminals of a mechanical potentiometer. The minimum voltage is VSS and the maximum is VCC. It should be noted that the terminology of VL and VH 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.

VW

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 400Ω.

Up/Down (U/D)

The U/D input controls the direction of the wiper movement and whether the counter is incremented or decremented.

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.

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 X9315 will be placed in the low power standby mode until the device is selected once again.

PIN CONFIGURATION

 

 

 

 

 

DIP/SOIC/MSOP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

8

 

 

VCC

 

INC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

U/D

 

 

2

7

 

 

CS

 

 

 

 

 

 

 

X9315

 

 

 

 

 

VH

 

 

3

6

 

 

VL

 

 

 

 

VSS

 

 

4

5

 

 

VW

 

 

 

6732 FM2

PIN NAMES

Symbol

Description

 

 

 

 

 

 

VH

High Terminal

 

VW

Wiper Terminal

 

 

VL

Low Terminal

VSS

Ground

VCC

Supply Voltage

 

 

 

 

 

 

Up/Down Input

 

U/D

 

 

 

 

 

 

 

 

 

 

 

 

 

Increment Input

 

INC

 

 

 

 

 

 

 

 

 

 

Chip Select Input

 

 

CS

 

 

 

 

 

 

 

6732 FM T01

2

X9315

DEVICE OPERATION

There are three sections of the X9315: 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 INC, U/D and CS inputs control the movement of the wiper along the resistor array. With CS set LOW the X9315 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 seven bit counter. The output of this counter is decoded to select one of thirty two wiper positions along the resistive array.

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.

The value of the counter is stored in nonvolatile memory whenever CS transistions HIGH while the INC input is also HIGH.

When the X9315 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.

Operation Notes

The system may select the X9315, 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 the keep INC LOW while taking CS HIGH. The new wiper position would be maintained until changed by the system or until a powerup/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 state of U/D may be changed while CS remains LOW. This allows the host system to enable the X9315 and then move the wiper up and down until the proper trim is attained.

SYMBOL TABLE

WAVEFORM

INPUTS

OUTPUTS

 

 

 

 

 

 

 

 

Must be

Will be

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

steady

steady

 

 

 

 

 

 

 

 

May change

Will change

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

from Low to

from Low to

 

 

 

 

 

 

 

 

High

High

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

May change

Will change

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

from High to

from High to

 

 

 

 

 

 

 

 

Low

Low

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Don’t Care:

Changing:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Changes

State Not

 

 

 

 

 

 

 

 

Allowed

Known

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

N/A

Center Line

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

is High

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Impedance

 

 

 

 

 

 

 

 

 

6732 FM 3

3

X9315

ABSOLUTE MAXIMUM RATINGS*

 

Temperature under Bias .........................

–65°C to +135°C

Storage Temperature..............................

–65°C to +150°C

Voltage on

 

 

 

 

 

VH, VL and VCC

 

CS,

INC,

U/D

 

with Respect to VSS..................................

 

–1V to +7V

V = |VH–VL| .................................................................

 

5V

Lead Temperature (Soldering 10 seconds)

............. 300°C

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

 

±1mA

ANALOG CHARACTERISTICS

 

 

Electrical Characteristics

 

 

Temperature under Bias.........................

–65°C to +135°C

End-to-End Resistance Tolerance

..........................

±20%

Power Rating at 25°C ..............................................

 

10mW

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

 

± 1mA Max.

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

 

400 Ω at 1mA

Typical Noise..................................

< –140dB√ Hz Ref: 1V

Resolution

 

 

Resistance ...................................................................

 

3%

Linearity

 

 

Absolute Linearity(1)...........................................

 

± 1.0 Ml(2)

Relative Linearity(3) ...........................................

 

± 0.2 Ml(2)

*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 specification is not implied.

Temperature Coefficient

 

(–40°C to +85°C) ..............................

+300 ppm/°C Typical

Ratiometric Temperature Coefficient

.................. ±20 ppm

Wiper Adjustability

Unlimited Wiper Adjustment (Non-Store operation)

Wiper Position Store Operations ..........................

100,000

Physical Characteristics

Marking Includes

Manufacturer’s Trademark

Resistance Value or Code

Date Code

Test Circuit #1

Test Circuit #2

VH

VH

TEST POINT

 

TEST POINT

VW

VW

FORCE

 

CURRENT

VL

VL

 

 

6732 FM 5

 

6732 FM 4

Notes: (1) Absolute Linearity is utilized to determine actual wiper voltage versus expected voltage

= (Vw(n)(actual) – Vw(n)(expected)) = ±1 Ml Maximum.

(2)1 Ml = Minimum Increment = RTOT/31.

(3)Relative Linearity is a measure of the error in step size between taps = VW(n+1) – [Vw(n) + Ml] = +0.2 Ml.

4

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