X9250 datasheet(3/21 Pages) XICOR

3 / 21 page

X9250

Characteristics subject to change without notice.

3 of 21

REV 1.1.5 1/31/03

www.xicor.com

PIN NAMES

DEVICE DESCRIPTION

Serial Interface

The X9250 supports the SPI interface hardware

conventions. The device is accessed via the SI input

with data clocked in on the rising SCK. CS must be

LOW and the HOLD and WP pins must be HIGH

during the entire operation.

The SO and SI pins can be connected together, since

they have three state outputs. This can help to reduce

system pin count.

Array Description

The X9250 is comprised of four resistor arrays. Each

array contains 255 discrete resistive segments that are

connected in series. The physical ends of each array

are equivalent to the ﬁxed terminals of a mechanical

potentiometer (VH/RH and VL/RL inputs).

At both ends of each array and between each resistor

segment is a CMOS switch connected to the wiper

(VW/RW) output. Within each individual array only one

switch may be turned on at a time.

These switches are controlled by a Wiper Counter

to select, and enable, one of 256 switches.

Wiper Counter Register (WCR)

The X9250 contains four Wiper Counter Registers,

one for each XDCP potentiometer. The WCR is

equivalent to a serial-in, parallel-out register/counter

with its outputs decoded to select one of 256 switches

along its resistor array. The contents of the WCR can

be altered in four ways: it may be written directly by the

host via the write Wiper Counter Register instruction

(serial load); it may be written indirectly by transferring

the contents of one of four associated Data Registers

via the XFR Data Register or Global XFR Data

one step at a time by the increment/decrement

instruction. Finally, it is loaded with the contents of its

Data Register zero (DR0) upon power-up.

The Wiper Counter Register is a volatile register; that

is, its contents are lost when the X9250 is powered-

down. Although the register is automatically loaded

with the value in R0 upon power-up, this may be

different from the value present at power-down.

Data Registers

Each potentiometer has four 8-bit nonvolatile Data

Registers. These can be read or written directly by the

host. Data can also be transferred between any of the

four Data Registers and the associated Wiper Counter

Data Registers is a nonvolatile operation and will take

a maximum of 10ms.

If the application does not require storage of multiple

settings for the potentiometer, the Data Registers can

be used as regular memory locations for system

parameters or user preference data.

Data Register Detail

Symbol

Description

SCK

Serial Clock

SI, SO

Serial Data

A0-A1

Device Address

VH0/RH0–VH3/RH3,

VL0/RL0–VL3/RL3

Potentiometer Pins

(terminal equivalent)

VW0/RW0–VW3/RW3

Potentiometer Pins

(wiper equivalent)

Hardware Write Protection

V+,V-

Analog Supplies

VCC

System Supply Voltage

VSS

System Ground

No Connection

(MSB)

(LSB)

X9250 Datasheet(PDF) 3 Page - Xicor Inc.

X9250 Datasheet(HTML) 3 Page - Xicor Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Datasheet Download

Link URL