Logarithmic Resistor

Rev 0; 11/07

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Maxim Integrated Products

1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

General Description

The DS1841 is a 7-bit, logarithmic, nonvolatile (NV) digi-

tal resistor that features an on-chip temperature sensor

and associated analog-to-digital converter (ADC). The

integrated temperature sensor indexes a 72-byte NV

lookup table (LUT) encompassing a temperature range

from -40°C to +100°C. The LUT output can drive the

resistor directly or be added to an NV initial-value regis-

ter (IVR) to drive the resistor. This flexible LUT-based

architecture allows the DS1841 to provide a tempera-

ture-compensated resistor output with arbitrary slope.

interface, which can operate at speeds of up to 400kHz.

Applications

Optical Transceivers

Linear and Nonlinear Compensation

Instrumentation and Industrial Controls

Mechanical Potentiometer Replacement

Features

♦ 22kΩ to 3.7kΩ Adjustable Logarithmic Resistor

with a 3.6k

Ω Fixed Resistor

♦ 128 Wiper Tap Points

♦ On-Chip Temperature Sensor and ADC

♦ 72-Byte Lookup Table (LUT)

♦ Address Pins Allow Up to Four DS1841s to Share

♦ Digital Supply of 2.7V to 5.5V

♦ -40°C to +100°C Operating Range

♦ 3mm x 3mm, 10-Pin TDFN Package

13

4

10

8

7

SCL

RH

RW

SDA

*EP

*EXPOSED PAD

A1

2

9

N.C.

GND

5

6

RGND

A0

TDFN

3.0mm

TOP VIEW

DS1841

Pin Configuration

Ordering Information

0.1

μF

3.3V

APD BIAS CONTROL APPLICATION

FB

SDA

SCL

A1

A0

GND

100pF

RW

RGND

RH

4.7k

Ω

4.7k

Ω

DC-DC

CONVERTER

DS1841

Typical Operating Circuit

+

Denotes a lead-free package.

T&R = Tape and reel.

Registers and Modes are capitalized for clarity.

PART

TEMP RANGE

PIN-PACKAGE

DS1841T+

-40°C to +100°C

10 TDFN

DS1841T+T&R

-40°C to +100°C

10 TDFN