Rev 1; 8/03
Triple 128-Position Nonvolatile Digital
Variable Resistor/Switch
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.
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
DS3904/DS3905
Ordering Information
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
8 µSOP
10 µSOP
RESISTANCE
20kΩ + Hi-Z
20kΩ + Hi-Z
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
DS3904U-020
DS3905U-020
Pin Configurations
TOP VEIW
SDA 1
SCL 2
V
CC
3
GND
4
8
7
A0
H0
H1
H2
A1 1
SDA 2
SDL 3
V
CC
GND
4
5
10 A2
9
A0
H0
H1
H2
DS3904
6
5
DS3905
8
7
6
µSOP
µSOP
Typical Operating Circuit
INTERFACE EXAMPLES
V
CC
V
CC
DS3904/DS3905
0.1µF
4.7kΩ
2-WIRE
MASTER
4.7kΩ
SCL
SDA
RESISTOR 1
20kΩ
ADDR F9h
RHIZ
H1
R
11
DIGITAL
LOGIC
2-WIRE
ADDRESSABLE
SWITCH (USING 00h
AND RHIZ SETTINGS)
V
CC
RESISTOR 0
20kΩ
ADDR F8h
RHIZ
H0
V
CC
R
10
VARIABLE RESISTANCE
FOR ADJUSTABLE
CURRENT SOURCE
A0
(DS3905 ONLY)
A1
A2
V
IN
RHIZ
H2
RESISTOR 2
20kΩ
ADDR FAh
GND
GAIN
CONTROL
R
12
_____________________________________________
Maxim Integrated Products
1
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.
DALLAS [ DALLAS SEMICONDUCTOR ]
