Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsData collecting ICsData acquisition IC - Digital potentiometer linear Permanent TDFN 8 EP

General Description

The MAX5422/MAX5423/MAX5424 nonvolatile, linear-

taper, digital potentiometers perform the function of a

mechanical potentiometer, but replace the mechanics

with a simple 3-wire SPI™-compatible digital interface.

Each device performs the same function as a discrete

potentiometer or variable resistor and has 256 tap points.

The devices feature an internal, nonvolatile EEPROM

used to store the wiper position for initialization during

power-up. The 3-wire SPI-compatible serial interface

allows communication at data rates up to 5MHz, mini-

mizing board space and reducing interconnection com-

plexity in many applications.

The MAX5422/MAX5423/MAX5424 provide three nomi-

nal resistance values: 50kΩ (MAX5422), 100kΩ

(MAX5423), or 200kΩ (MAX5424). The nominal resistor

temperature coefficient is 35ppm/°C end-to-end and

only 5ppm/°C ratiometric. This makes the devices ideal

for applications requiring a low-temperature-coefficient

variable resistor, such as low-drift, programmable gain-

amplifier circuit configurations.

The MAX5422/MAX5423/MAX5424 are available in a

3mm x 3mm 8-pin TDFN package, and are specified

over the extended -40°C to +85°C temperature range.

Applications

Mechanical Potentiometer Replacement

Low-Drift Programmable Gain Amplifiers

Audio Volume Control

Liquid-Crystal Display (LCD) Contrast Control

Low-Drift Programmable Filters

Features

♦ Wiper Position Stored in Nonvolatile Memory

(EEPROM) and Recalled Upon Power-Up or

Interface Command

♦ 3mm x 3mm x 0.8mm TDFN Package

♦ 35ppm/°C End-to-End Resistance Temperature

Coefficient

♦ 5ppm/°C Ratiometric Temperature Coefficient

♦ 50kΩ, 100kΩ, and 200kΩ Resistor Values

♦ 5MHz SPI-Compatible Serial Interface

♦ 500nA (typ) Static Supply Current

♦ Single-Supply Operation: +2.7V to +5.25V

♦ 256 Tap Positions

♦ ±0.5 LSB DNL in Voltage-Divider Mode

♦ ±0.5 LSB INL in Voltage-Divider Mode

MAX5422/MAX5423/MAX5424

256-Tap, Nonvolatile, SPI-Interface,

Digital Potentiometers

________________________________________________________________ Maxim Integrated Products 1

Ordering Information/Selector Guide

19-3371; Rev 0; 7/04

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.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE

END-TO-END

RESISTANCE (kΩ)

PIN-PACKAGE TOP MARK

MAX5422ETA -40°C to +85°C50

8 TDFN-EP*

AIJ

MAX5423ETA -40°C to +85°C 100

8 TDFN-EP*

AII

MAX5424ETA -40°C to +85°C 200

8 TDFN-EP*

AIH

SCLK

DIN

GND

TDFN (3mm x 3mm)

TOP VIEW

MAX5422

MAX5423

MAX5424

Pin Configuration

SPI

INTERFACE

256-

POSITION

DECODER

GND

SCLK

8-BIT

MEMORY

8-BIT

LATCH

8-BIT

SHIFT

POR

256

DIN

MAX5422

MAX5423

MAX5424

Functional Diagram

SPI is a trademark of Motorola, Inc.

*EP = Exposed pad.

Summary of content (11 pages)

PAGE 1
9-3371; Rev 0; 7/04 KIT ATION EVALU E L B AVAILA 256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers Features ♦ Wiper Position Stored in Nonvolatile Memory (EEPROM) and Recalled Upon Power-Up or Interface Command ♦ 3mm x 3mm x 0.8mm TDFN Package ♦ 35ppm/°C End-to-End Resistance Temperature Coefficient ♦ 5ppm/°C Ratiometric Temperature Coefficient ♦ 50kΩ, 100kΩ, and 200kΩ Resistor Values ♦ 5MHz SPI-Compatible Serial Interface ♦ 500nA (typ) Static Supply Current ♦ Single-Supply Operation: +2.
PAGE 2
MAX5422/MAX5423/MAX5424 256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers ABSOLUTE MAXIMUM RATINGS VDD to GND ...........................................................-0.3V to +6.0V All Other Pins to GND.................................-0.3V to (VDD + 0.3V) Maximum Continuous Current into H, L, and W MAX5422......................................................................±1.3mA MAX5423......................................................................±0.6mA MAX5424......................
PAGE 3
256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers (VDD = +2.7V to +5.25V, H = VDD, L = GND, TA = -40°C to +85°C. Typical values are at VDD = +5.0V, TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DIGITAL INPUTS (CS, DIN, SCLK) VDD = 3.4V to 5.25V Input High Voltage (Note 4) VIH Input Low Voltage VIL 2.4 V 0.7 x VDD VDD < 3.4V VDD = 2.7V to 5.25V (Note 4) Input Leakage Current IIN ±0.1 Input Capacitance CIN 5 0.
PAGE 4
TIMING CHARACTERISTICS (continued) (VDD = +2.7V to +5.25V, H = VDD, L = GND, TA = -40°C to +85°C. Typical values are at VDD = +5.0V, TA = +25°C, unless otherwise noted. See Figure 1.
PAGE 5
256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers STANDBY SUPPLY CURRENT vs. TEMPERATURE END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE MAX5422 toc04 CL = 10pF TAP = 128 H = VDD 0.8 0.6 0.9 0.8 SUPPLY CURRENT (μA) W 1V/div 1.0 MAX5422toc05 VDD 1V/div END-TO-END RESISTANCE % CHANGE 1.0 0.4 0.2 0 -0.2 -0.4 0.7 0.6 0.4 -0.8 0.1 -1.0 0 -15 10 35 60 VDD = 4.0V 0.3 0.2 -40 VDD = 5.25V 0.5 -0.6 4μs/div MAX5422 toc06 WIPER TRANSIENT AT POWER-ON VDD = 3.0V VDD = 2.
PAGE 6
Typical Operating Characteristics (continued) (VDD = 5.0V, TA = +25°C, unless otherwise noted.) INL vs. TAP POSITION (MAX5424) VARIABLE-RESISTOR MODE VDD = 2.7V ISRC = 10μA 1.5 VARIABLE-RESISTOR MODE 0.2 0.5 0 0 0 -0.1 -0.5 -0.5 -0.2 -1.0 -1.0 0 32 64 96 128 160 192 224 256 -0.3 0 32 64 TAP POSITION 96 128 160 192 224 256 0 32 64 TAP POSITION 0.2 DNL vs. TAP POSITION (MAX5424) 0.5 MAX5422 toc14 VARIABLE-RESISTOR MODE 128 160 192 224 256 TAP POSITION DNL vs.
PAGE 7
256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers PIN NAME 1 VDD FUNCTION 2 SCLK Serial-Interface Clock Input 3 DIN Serial-Interface Data Input 4 CS Active-Low Digital-Input Chip Select 5 GND Power-Supply Input. Bypass VDD with a 0.1µF capacitor from VDD to GND. Ground 6 L Low Terminal. The voltage at L can be greater than or less than the voltage at H. Current can flow into or out of L. 7 W Wiper Terminal 8 H High Terminal.
PAGE 8
MAX5422/MAX5423/MAX5424 256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers (CS), data clock (SCLK), and data in (DIN). Drive CS low to enable the serial interface and clock data synchronously into the shift register on each SCLK rising edge. The WRITE commands (C1, C0 = 00 or 01) require 16 clock cycles to clock in the command and data (Figure 2a).
PAGE 9
256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers Write NV Register The “write NV register” command (C1, C0 = 01) stores the position of the wipers to the NV registers for use at power-up. Alternatively, the “copy wiper register to NV register” command writes to the NV register. Writing to the NV registers, does not affect the position of the wipers.
PAGE 10
MAX5422/MAX5423/MAX5424 256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers Programmable Filter Adjustable Voltage Reference Figure 5 shows the configuration for a 1st-order programmable filter. The gain of the filter is adjusted by R2, and the cutoff frequency is adjusted by R3. Use the following equations to calculate the DC gain (G) and the 3dB cutoff frequency (fC): Figure 6 shows the MAX5422/MAX5423/MAX5424 used as the feedback resistors in an adjustable voltage-reference application.
PAGE 11
256-Tap, Nonvolatile, SPI-Interface, Digital Potentiometers 6, 8, &10L, DFN THIN.EPS COMMON DIMENSIONS PACKAGE VARIATIONS SYMBOL MIN. MAX. PKG. CODE N D2 E2 e JEDEC SPEC b [(N/2)-1] x e A 0.70 0.80 T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF D 2.90 3.10 T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF E 2.90 3.10 T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF A1 0.00 0.05 T1033-1 10 1.