General Description

The DS3904/DS3905 contain three nonvolatile (NV) low

temperature coefficient, variable digital resistors. Each

resistor has 128 user-selectable positions. Additionally,

the DS3904/DS3905 have a high-impedance setting that

allows each resistor to function as a digital switch. The

DS3904/DS3905 can operate over a 2.7V to 5.5V supply

voltage range, and communication with the device is

achieved through a 2-wire serial interface. Address pins

allow multiple DS3904/DS3905s to operate on the same

two-wire bus. The DS3904 has one address pin, allow-

ing two DS3904s to share the bus, while the DS3905

has three address pins, allowing up to eight DS3905s to

share a common bus. The low-cost and small size of the

DS3904/DS3905 make them ideal replacements for con-

ventional mechanical trimming resistors.

Applications

Power-Supply Calibration

Cell Phones and PDAs

Fibre Optic Transceiver Modules

Portable Electronics

Small and Low-Cost Replacement for

Conventional Mechanical Trimming Resistors/

Dip Switches

Test Equipment

Features

♦ Three 20kΩ, 128-Position Linear Digital Resistors

♦ Resistor Settings are Stored in NV Memory

♦ Each Resistor has a High-Impedance Setting for

Switch Operation to Control Digital Logic

♦ Low Temperature Coefficient

♦ 2-Wire Serial Interface

♦ 2.7V to 5.5V Operating Range

♦ -40°C to +85°C Industrial Temperature

♦ Packaging: 8-Pin µSOP for DS3904, 10-pin µSOP

for DS3905

Triple 128-Position Nonvolatile Digital

Variable Resistor/Switch

_____________________________________________ Maxim Integrated Products

1

8

6

5

1

3

4

SDA

TOP VEIW

A0

7

2

SCL

H0

H1

H2

µSOP

GND

DS3904

10

1

A1

A2

9

2

SDA

A0

µSOP

8

3H0

SDL

7

4

H1

6

5

H2

GND

DS3905

Pin Configurations

0.1

µF

4.7k

Ω

2-WIRE

MASTER

H0

H1

H2

RHIZ

SCL

SDA

(DS3905 ONLY)

A1

A2

RESISTOR 0

20k

Ω

ADDR F8h

RESISTOR 1

20k

Ω

ADDR F9h

RESISTOR 2

20k

Ω

ADDR FAh

A0

GND

4.7k

Ω

VARIABLE RESISTANCE

FOR ADJUSTABLE

CURRENT SOURCE

INTERFACE EXAMPLES

2-WIRE

ADDRESSABLE

SWITCH (USING 00h

AND RHIZ SETTINGS)

GAIN

CONTROL

DS3904/DS3905

RHIZ

RHIZ

DIGITAL

LOGIC

Typical Operating Circuit

Ordering Information

Rev 1; 8/03

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART

TEMP RANGE

PIN-

PACKAGE

RESISTANCE

DS3904U-020

-40

°C to +85°C 8 µSOP

20k

Ω + Hi-Z

DS3905U-020

-40

°C to +85°C 10 µSOP

20k

Ω + Hi-Z