Rainbow Electronics DS3904 User Manual

General Description

The DS3904 contains three nonvolatile (NV) low tem­perature coefficient variable digital resistors. Each
resistor has 128 user-selectable positions. Additionally,
the DS3904 has a high-impedance option that allows
each resistor to function as a digital switch. The
DS3904 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. An address pin allows
two DS3904s to operate on the same bus. The low-cost
and small size of the DS3904 make it an ideal replace­ment for conventional 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

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
♦ Industrial Temperature Range: -40°C to +85°C
♦ Packaging: 8-Pin µSOP

DS3904

Triple 128-Position Nonvolatile

Variable Digital Resistor/Switch

_____________________________________________ Maxim Integrated Products 1

8

6

5

1

3

4

SDA

A0

72

SCL

H0

H1

H2

µSOP

V

CC

GND

DS3904

Pin Configuration

0.1µF

4.7kΩ

2-WIRE

MASTER

V

CC

V

CC

H0

H1

H2

RHIZ

1.75kΩ

V

CC

SCL

SDA

RESISTOR 0
20kΩ
ADDR F8h

RESISTOR 1
20kΩ
ADDR F9h

RESISTOR 2
20kΩ
ADDR FAh

A0

GND

4.7kΩ

VARIABLE RESISTANCE
FOR ADJUSTABLE
CURRENT SOURCE

2-WIRE
ADDRESSABLE
SWITCH (USING 00h
AND RHIZ)

GAIN
CONTROL

V

IN

DS3904

V

CC

RHIZ

RHIZ

5.1kΩ
DIGITAL

LOGIC

20kΩ

Typical Operating Circuit

Ordering Information

Rev 0; 1/03

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

PIN­PACKAGE

RESISTANCE

DS3904

-40°C to +85°C

8 µSOP

20kΩ + Hi-Z

DS3904

DS3904 Triple 128-Position Nonvolatile
Variable Digital Resistor/Switch

2 ______________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

RECOMMENDED DC OPERATING CONDITIONS

(TA= -40°C to +85°C)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

Voltage on VCCPin Relative to Ground.................-0.5V to +6.0V

Voltage on SDA, SCL, and

A0 Relative to Ground* .............................-0.5V to V

CC

+ 0.5V

Voltage on H0, H1, and

H2 Relative to Ground.......-0.5V to +6.0V when V

CC

Powered

Current Through H0, H1, and H2..........................................3mA

Operating Temperature Range ...........................-40°C to +85°C

Programming Temperature Range .........................0°C to +70°C

Storage Temperature Range .............................-55°C to +125°C

Soldering Temperature ................See J-STD-020A Specification

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Supply Voltage V

CC

(Note 1) 2.7 5.5 V

Input Logic 1 V

IH

0.7 x

V

CC

+

0.3

V

Input Logic 0 V

IL

0.3 x
V

Resistor Current I

R

3mA

Resistor Terminals
H0, H1, H2

V

CC

= +2.7V to +5.5V

V

DC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C, unless otherwise noted.)

PARAMETER

CONDITIONS

UNITS

Input Leakage I

L

(Note 2) -1 +1 µA

V

CC

= 3V (Note 3) 95

Standby Supply Current I

STBY

V

CC

= 5V (Note 3)

200 µA

V

OL1

3mA sink current 0 0.4

Low-Level Output Voltage (SDA)

V

OL2

6mA sink current 0 0.6

V

ANALOG RESISTOR CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C, unless otherwise noted.)

PARAMETER

CONDITIONS

Absolute Linearity (Note 4) -1 +1 LSB

Relative Linearity (Note 5)

LSB

Temperature Coefficient Position 7Fh (Note 6)

Position 7Fh Resistance R

MAX

TA = +25°C

20

kΩ

Position 00h Resistance R

MIN

T

A

= +25°C 200 500 Ω

High Impedance R

HI-Z

5MΩ

*This voltage must not exceed 6.0V.

V

CC

-0.3

-0.3 +5.5

SYMBOL

MIN TYP MAX

145

SYMBOL

MIN TYP MAX UNITS

-0.5 +0.5

-200 +123 +400 ppm/°C

14.5

V

CC

25.5

DS3904

DS3904 Triple 128-Position Nonvolatile

Variable Digital Resistor/Switch

_____________________________________________________________________ 3

AC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C.)

PARAMETER

CONDITIONS

UNITS

Fast mode (Note 7) 0 400

SCL Clock Frequency f

SCL

Standard mode (Note 7) 0 100

kHz

Fast mode (Note 7) 1.3

Bus Free Time between STOP
and START Conditions

t

BUF

Standard mode (Note 7) 4.7

µs

Fast mode (Notes 7, 8) 0.6

Hold Time (Repeated) START
Condition

Standard mode (Notes 7, 8) 4.0

µs

Fast mode (Note 7) 1.3

Low Period of SCL Clock t

LOW

Standard mode (Note 7) 4.7

µs

Fast mode (Note 7) 0.6

High Period of SCL Clock t

HIGH

Standard mode (Note 7) 4.0

µs

Fast mode (Notes 7, 9, 10) 0 0.9

Data Hold Time

Standard mode (Notes 7, 9, 10) 0 0.9

µs

Fast mode (Note 7)

Data Setup Time

Standard mode (Note 7)

ns

Fast mode 0.6

Start Setup Time

Standard mode 4.7

µs

Fast mode (Note 11)

300

Rise Time of Both SDA and SCL
Signals

t

R

Standard mode (Note 11)

ns

Fast mode (Note 11)

300

Fall Time of Both SDA and SCL
Signals

t

F

Standard mode (Note 11)

300

ns

Fast mode 0.6

Setup Time for STOP Condition

Standard mode 4.0

µs

Capacitive Load for Each Bus
Line

C

B

(Note 11) 400 pF

EEPROM Write Time t

W

(Note 12) 20 ms

Startup Time t

ST

2ms

NONVOLATILE MEMORY CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C.)

PARAMETER

CONDITIONS

UNITS

Writes 85°C

SYMBOL

t

t

t

t

t

SYMBOL

MIN TYP MAX

HD:STA

HD:DAT

SU:DAT

SU:STA

SU:STO

100

250

20 + 0.1C

20 + 0.1C

20 + 0.1C

20 + 0.1C

50,000

B

B

B

B

MIN TYP MAX

1000

DS3904

DS3904 Triple 128-Position Nonvolatile
Variable Digital Resistor/Switch

4 ______________________________________________________________________

Note 1: All voltages are referenced to ground.
Note 2: Applies to AO, SCL, SDA as well as H0, H1, and H2 in the high-impedance state.
Note 3: I

STBY

specified with SDA = SCL = VCCand A0 = GND.

Note 4: Absolute linearity is used to determine expected resistance. Absolute linearity is defined as the deviation

from the straight line drawn from the value of the resistance at position 00h to the value of the resistance at
position 7Fh.

Note 5: Relative linearity is used to determine the change of resistance between two adjacent resistor positions.
Note 6: Temperature coefficient specifies the change in resistance as a function of temperature. The temperature

coefficient varies with resistor position. Guaranteed by design.

Note 7: A fast-mode device can be used in a standard-mode system, but the requirement t

SU:DAT

> 250ns must
then be met. This is automatically the case if the device does not stretch the LOW period of the SCL signal.
If such a device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA
line t

RMAX

+ t

SU:DAT

= 1000ns + 250ns =1250ns before the SCL line is released.

Note 8: After this period, the first clock pulse is generated.
Note 9: The maximum t

HD:DAT

has only to be met if the device does not stretch the LOW period (t

LOW

) of the SCL

signal.

Note 10: A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the V

IN MIN

of

the SCL signal) in order to bridge the undefined region of the falling edge of SCL.

Note 11: C

B

—total capacitance of one bus line in picofarads, timing referenced to 0.9 x VCCand 0.1 x VCC.

Note 12: EEPROM write begins after a stop condition occurs.

AC ELECTRICAL CHARACTERISTICS (continued)

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C.)