DS3502(2008) View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

DS3502
(Rev.:2008)

High-Voltage, NV, I2C POT

Maxim Integrated 

High-Voltage, NV, I2C POT

Simplified Functional Diagram

VCC

GND

SCL

I2C

INTERFACE

SDA

A0

A1

DS3502

CONTROL

LOGIC/

REGISTER

(02h)

MODE BIT

WIPER

REGISTER/

INITIAL VALUE

REGISTER

(WR/IVR)

00h

V+

RH

POS 7Fh

RW

POS 00h

RL

Detailed Description

The DS3502 contains a single potentiometer whose

wiper position is controlled by the value in the Wiper

Register (WR). The initial power-up value of the wiper

position is set by programming the Initial Value Register

(IVR). On power-up, the data stored in the IVR register

is loaded into the WR register, which sets the position

of the potentiometer’s wiper.

Control Register

The Control Register (CR) located in register 02h con-

tains the WR/IVR Address Mode bit (MODE bit). The

MODE bit determines how I2C data is written to the WR

and IVR data register as follows:

MODE = 0: I2C writes to memory address 00h write to

(CR = 00h) both WR and IVR.

I2C reads from address 00h read from WR.

MODE = 1: I2C writes to memory address 00h write to

(CR = 80h) WR.

I2C reads from address 00h read from WR.

Table 1. Memory Map

REGISTER

WR/IVR

CR

NAME

Wiper Register/Initial Value Register

Control Register

Regardless of the setting of the MODE bit, all I2C reads

of address 00h return the contents of the WR register.

Setting MODE = 1 allows for quick writing of SRAM

without the added delay of writing to the associated

EEPROM register. The data that is stored in EEPROM

and SRAM remains unchanged if the MODE bit is tog-

gled. The volatile CR register powers up as 00h, set-

ting the device into MODE = 0.

Digital Potentiometer Output

The potentiometer consists of 127 resistors in series

connected between the RH and RL pins. Between each

resistance and at the two endpoints, RH and RL, solid-

state switches enable RW to be connected within the

resistive network. The wiper position and the output on

RW are decoded based on the value in WR. If RH, RL,

and RW are externally connected in a voltage-divider

configuration, then the voltage on RW can be easily

calculated using the following equation:

VRW

=

VRL

+

WR

127

(VRH

−

VRL )

where WR is the wiper position in decimal (0–127).

ADDRESS

(HEX)

00

02

FACTORY/POWER-UP DEFAULT

(HEX)

40

00 (Mode 0)

6 _______________________________________________________________________________________

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