Datasheet

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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 20k

ΩΩ

, or Two 20k

ΩΩ

and One 10k

ΩΩ

, 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

Triple 128-Position Nonvolatile Digital

Variable Resistor/Switch

_____________________________________________

Maxim Integrated Products

Pin Configurations

0.1μF

4.7kΩ

2-WIRE

MASTER

RHIZ

SCL

SDA

(DS3905 ONLY)

RESISTOR 0

ADDR F8h

RESISTOR 1

ADDR F9h

RESISTOR 2

ADDR FAh

GND

4.7kΩ

VARIABLE RESISTANCE

FOR ADJUSTABLE

CURRENT SOURCE

INTERFACE EXAMPLES

2-WIRE

ADDRESSABLE

SWITCH (USING 00h

AND RHIZ SETTINGS)

GAIN

CONTROL

DS3904/DS3905

RHIZ

DIGITAL

LOGIC

Typical Operating Circuit

Ordering Information

Rev 3; 3/07

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

(R0/R1/R2)

RESISTANCE (k)

DS3904U-010 -40°C to +85°C 8 μSOP 20/10/20 + High-Z

DS3904U-020 -40°C to +85°C 8 μSOP 20/20/20 + High-Z

DS3905U-020 -40°C to +85°C 10 μSOP 20/20/20 + High-Z

SDA

TOP VEIW

SCL

μSOP

GND

DS3904

101

SDA

μSOP

83H0SDL

H1V

H2GND

DS3905

Summary of content (11 pages)

PAGE 1
Rev 3; 3/07 Triple 128-Position Nonvolatile Digital Variable Resistor/Switch 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.
PAGE 2
DS3904/DS3905 Triple 128-Position Nonvolatile Variable Digital Resistor/Switch ABSOLUTE MAXIMUM RATINGS Voltage on VCC Pin Relative to Ground.................-0.5V to +6.0V Voltage on SDA, SCL, A0, A1, A2 Relative to Ground*...................................-0.5V to VCC + 0.5V Voltage on H0, H1, and H2 Relative to Ground .......................................-0.5V to +6.0V Current Through H0, H1, and H2..........................................3mA Operating Temperature Range ...........................
PAGE 3
Triple 128-Position Nonvolatile Digital Variable Resistor/Switch DS3904/DS3905 ANALOG RESISTOR CHARACTERISTICS (continued) (VCC = +2.7V to +5.5V, TA = -40°C to +85°C, unless otherwise noted.) PARAMETER SYMBOL Position 7Fh Resistance RMAX Position 00h Resistance RMIN High Impedance RHIZ CONDITIONS TA = +25°C (20k resistor) MIN 14.5 TYP 20 MAX 25.5 TA = +25°C (10k resistor) 8 10 12 TA = +25°C 200 500 5.5 UNITS k M AC ELECTRICAL CHARACTERISTICS (VCC = +2.7V to +5.
PAGE 4
DS3904/DS3905 Triple 128-Position Nonvolatile Digital Variable Resistor/Switch NONVOLATILE MEMORY CHARACTERISTICS (VCC = +2.7V to +5.5V, TA = +70°C.) PARAMETER SYMBOL CONDITIONS EEPROM Writes MIN TYP MAX UNITS 50,000 All voltages are referenced to ground. Applies to A0, SDA, SCL for the DS3904 and A0, A1, A2, SDA, SCL for the DS3905. Also applies to H0, H1, H2 for both DS3904 and DS3905 when in the high-impedance state. Note 3: ISTBY specified with SDA = SCL = VCC and A0 = GND.
PAGE 5
Triple 128-Position Nonvolatile Digital Variable Resistor/Switch SUPPLY CURRENT vs. TEMPERATURE SUPPLY CURRENT vs. SCL FREQUENCY 80 60 SDA = SCL =VCC ADDRESS PINS CONNECTED TO GND 80 10kΩ RESISTOR 0 20 40 60 0 80 TEMPERATURE COEFFICIENT vs.
PAGE 6
Typical Operating Characteristics (continued) (VCC = +5.0V, TA = +25°C, unless otherwise noted.) 10 10kΩ RESISTOR 5 0 3.0 3.5 4.0 4.5 5.0 5.5 0.1 0 -0.1 -0.2 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.4 -0.5 0 20 40 60 80 100 0 120 80 100 ABSOLUTE LINEARITY vs. RESISTOR 1 POSITION RELATIVE LINEARITY vs. RESISTOR 1 POSITION ABSOLUTE LINEARITY vs. RESISTOR 2 POSITION -0.2 0.2 0.1 0 -0.1 -0.2 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.3 -0.4 -0.4 -0.4 -0.5 -0.5 40 60 80 100 -0.
PAGE 7
Triple 128-Position Nonvolatile Digital Variable Resistor/Switch NAME PIN DS3904 DS3905 DESCRIPTION Table 1. Variable Resistor Registers ADDRESS VARIABLE RESISTOR POSITION 7Fh RESISTANCE NUMBER OF POSITIONS* SDA 1 2 2-Wire Serial Data. Open-drain input/output for 2-wire data. F8h Resistor 0 20k (nominal) 128 (00h to 7Fh) + Hi-Z SCL 2 3 2-Wire Serial Clock. Input for 2-wire clock.
PAGE 8
DS3904/DS3905 Triple 128-Position Nonvolatile Digital Variable Resistor/Switch VCC EEPROM VCC DS3905 H0 RHIZ CONTROL F8h RESISTOR 0 MSB 7 LSB RES 0 20kΩ GND H1 RHIZ CONTROL SCL DATA SDA (DS3905 ONLY) A0 A1 A2 2-WIRE INTERFACE F9h RESISTOR 1 MSB 7 LSB RES 1 20kΩ OR 10kΩ FAh RESISTOR 2 MSB 7 LSB Acknowledge Polling H2 RHIZ CONTROL where the data is to be written.
PAGE 9
Triple 128-Position Nonvolatile Digital Variable Resistor/Switch DS3904/DS3905 SDA MSB SLAVE ADDRESS R/W DIRECTION BIT ACKNOWLEDGEMENT SIGNAL FROM RECEIVER ACKNOWLEDGEMENT SIGNAL FROM RECEIVER SCL 1 2 6 7 8 9 1 2 3–7 8 ACK START CONDITION 9 ACK REPEATED IF MORE BYTES ARE TRANSFERRED STOP CONDITION OR REPEATED START CONDITION Figure 2.
PAGE 10
DS3904/DS3905 Triple 128-Position Nonvolatile Digital Variable Resistor/Switch COMMAND BYTE MSB START 1 0 1 0 A device that acknowledges must pull down the SDA line during the acknowledge clock pulse in such a way that the SDA line is a stable low during the high period of the acknowledge-related clock pulse. Of course, setup and hold times must be taken into account.
PAGE 11
Triple 128-Position Nonvolatile Digital Variable Resistor/Switch Power-Supply Decoupling 1) Slave Receiver Mode: Serial data and clock are received through SDA and SCL, respectively. After each byte is received, an acknowledge bit is transmitted. Start and stop conditions are recognized as the beginning and end of a serial transfer. Address recognition is performed by hardware after the slave (device) address and direction bit has been received.