Datasheet

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General Description

The MAX5402 µPoT

™

digital potentiometer is a 256-tap

variable resistor with 10kΩ total resistance in a tiny 8-

pin µMAX package. This device functions as a mechan-

ical potentiometer, consisting of a fixed resistor string

with a digitally controlled wiper contact. It operates

from +2.7V to +5.5V single-supply voltages and uses

an ultra-low 0.1µA supply current. This device also pro-

vides glitchless switching between resistor taps, as well

as a convenient power-on reset (POR) that sets the

wiper to the midscale position at power-up. A low

5ppm/°C ratiometric temperature coefficient makes it

ideal for applications requiring low drift.

The MAX5402 serves well in applications requiring digi-

tally controlled resistors, including adjustable voltage

references and programmable gain amplifiers (PGAs).

A nominal end-to-end resistor temperature coefficient of

35ppm/°C makes this part suitable for use as a variable

resistor in applications such as low-tempco adjustable

gain and other circuit configurations. This device is

guaranteed over the extended industrial temperature

range (-40°C to +85°C).

________________________Applications

Mechanical Potentiometer Replacement

Low-Drift PGAs

Adjustable Voltage References

Features

♦ Small Footprint, 8-Pin µMAX Package

♦ Ultra-Low 100nA Supply Current

♦ +2.7V to +5.5V Single-Supply Operation

♦ 256 Tap Positions

♦ Low Ratiometric Temperature Coefficient

5ppm/°C

♦ Low End-to-End Resistor Temperature Coefficient

35ppm/°C

♦ Power-On Reset: Wiper Goes to Midscale

(Position 128)

♦ Glitchless Switching Between the Resistor Taps

♦ 3-Wire SPI™-Interface Compatible

♦ 10kΩ Resistor Value

MAX5402

256-Tap, µPoT, Low-Drift,

Digital Potentiometer

SCLKDIN

WGND

µMAX

TOP VIEW

MAX5402

Pin Configuration

19-1896; Rev 0; 1/01

Ordering Information

µPoT is a trademark of Maxim Integrated Products.

SPI is a trademark of Motorola, Inc.

PART

TEMP.

RANGE

PIN-

PACKAGE

R (kΩ)

MAX5402EUA -40°C to +85°C 8 µMAX 10

________________________________________________________________ Maxim Integrated Products 1

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,

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

MAX5402

POR

8-BIT

SHIFT

CLOCK

LOGIC

8-BIT

LATCH

SCLK

DIN

DECODE

GND

256

Functional Diagram

Summary of content (9 pages)

PAGE 1
9-1896; Rev 0; 1/01 256-Tap, µPoT, Low-Drift, Digital Potentiometer The MAX5402 serves well in applications requiring digitally controlled resistors, including adjustable voltage references and programmable gain amplifiers (PGAs). A nominal end-to-end resistor temperature coefficient of 35ppm/°C makes this part suitable for use as a variable resistor in applications such as low-tempco adjustable gain and other circuit configurations.
PAGE 2
MAX5402 256-Tap, µPoT, Low-Drift, Digital Potentiometer ABSOLUTE MAXIMUM RATINGS VDD to GND ..............................................................-0.3V to +6V DIN, SCLK, CS to GND ............................................-0.3V to +6V H, L, W to GND .............................................-0.3V to (VDD + 0.3) Maximum Continuous Current into Pins H, L, and W ...........1mA Continuous Power Dissipation (TA = +70°C) 8-Pin µMAX (derate 4.1mW/°C above +70°C) ............
PAGE 3
256-Tap, µPoT, Low-Drift, Digital Potentiometer (VDD = +5V, VH = VDD, VL = 0, TA = TMIN to TMAX. Typical values are at VDD = +5V, TA = +25°C, unless otherwise noted.
PAGE 4
Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE WIPER RESISTANCE vs. WIPER VOLTAGE 250 VDD = +3V 225 200 MAX5402 Toc02 0.00 -0.05 VDD = +5V 175 -0.10 150 -0.15 125 -0.20 100 0 1 2 3 4 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 5 WIPER VOLTAGE (V) TEMPERATURE (°C) RESISTANCE vs. INPUT CODE VARIABLE RESISTOR DNL vs. INPUT CODE 0.25 MAX5402 Toc03 10 9 8 0.20 0.15 7 RDNL (LSB) W-TO-L RESISTANCE (kΩ) 0.
PAGE 5
256-Tap, µPoT, Low-Drift, Digital Potentiometer VOLTAGE-DIVIDER INL vs. INPUT CODE SUPPLY CURRENT vs. TEMPERATURE 1.0 SUPPLY CURRENT (µA) 0.10 0.05 0.00 -0.05 -0.10 MAX5402 Toc08 0.15 INL (LSB) 1.2 MAX5402 Toc07 0.20 VDD = +5V 0.8 0.6 0.4 0.2 -0.15 VDD = +3V -0.20 0.0 0 32 64 96 128 160 192 224 256 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 INPUT CODE (DECIMAL) TEMPERATURE (°C) INPUT LOGIC VOLTAGE TAP-TO-TAP SWITCHING TRANSIENT MAX5402 toc09 MAX5402 Toc10 10 +2.51V +2.
PAGE 6
MAX5402 256-Tap, µPoT, Low-Drift, Digital Potentiometer POT REGISTER LOADED CS SCLK 8TH CLOCK PULSE 1ST CLOCK PULSE DIN D7 D6 D5 D4 D3 D2 D1 D0 LSB MSB TIME Figure 1. Serial Interface Timing Diagram CS tCSW tCSO tCS1 tCSS tCL tCH tCP tCSH SCLK tDS tDH DIN Figure 2. Detailed Serial Interface Timing Diagram Detailed Description The MAX5402 consists of 255 fixed resistors in series between pins H and L.
PAGE 7
256-Tap, µPoT, Low-Drift, Digital Potentiometer B1 (D6) B2 (D5) B3 (D4) B4 (D3) B5 (D2) B6 (D1) MAX5402 Data Word B0 (D7) B7 (D0) (MSB) First Bit In (LSB) Last Bit In Figure 3. Serial Data Format Applications Information The MAX5402 is intended for a variety of circuits where accurate, fine-tuned adjustable resistance is required, such as in adjustable voltage or adjustable gain circuit configurations. The MAX5402 is used in either a potentiometer divider or a variable resistor configuration.
PAGE 8
256-Tap, µPoT, Low-Drift, Digital Potentiometer MAX5402 Chip Information +5V TRANSISTOR COUNT: 3475 PROCESS: BiCMOS VIN VO REF OUT H MAX6160 ADJ W GND VO = MAX5402 L 1.23V ✕ 255 C WHERE C IS THE DECIMAL EQUIVALENT WRITTEN CODE. Figure 6.
PAGE 9
256-Tap, µPoT, Low-Drift, Digital Potentiometer 8LUMAXD.EPS Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.