Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsData collecting ICsData acquisition IC - Digital potentiometer linear Permanent TQFN 16

General Description

The MAX5477/MAX5478/MAX5479 nonvolatile, dual,

linear-taper, digital potentiometers perform the function

of a mechanical potentiometer, but replace the

mechanics with a simple 2-wire digital interface. Each

device performs the same function as a discrete poten-

tiometer 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. A write-protect feature prevents accidental

overwrites of the EEPROM. The fast-mode I

C-compati-

ble serial interface allows communication at data rates

up to 400kbps, minimizing board space and reducing

interconnection complexity in many applications. Three

address inputs allow a total of eight unique address

combinations.

The MAX5477/MAX5478/MAX5479 provide three nomi-

nal resistance values: 10kΩ (MAX5477), 50kΩ

(MAX5478), or 100kΩ (MAX5479). The nominal resistor

temperature coefficient is 70ppm/°C end-to-end and

10ppm/°C ratiometric. The low temperature coefficient

makes the devices ideal for applications requiring a low-

temperature-coefficient variable resistor, such as low-

drift, programmable gain-amplifier circuit configurations.

The MAX5477/MAX5478/MAX5479 are available in 16-

pin 3mm x 3mm x 0.8mm TQFN and 14-pin 4.4mm x

5mm TSSOP packages. These devices operate over

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

Applications

Mechanical Potentiometer Replacement

Low-Drift Programmable-Gain Amplifiers

Volume Control

Liquid-Crystal Display (LCD) Contrast Control

Features

o Power-On Recall of Wiper Position from

Nonvolatile Memory

o EEPROM Write Protection

o Tiny 3mm x 3mm x 0.8mm Thin QFN Package

o 70ppm/°C End-to-End Resistance Temperature

Coefficient

o 10ppm/°C Ratiometric Temperature Coefficient

o Fast 400kbps I

C-Compatible Serial Interface

o 1µA (max) Static Supply Current

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

o 256 Tap Positions per Potentiometer

o ±0.5 LSB DNL in Voltage-Divider Mode

o ±1 LSB INL in Voltage-Divider Mode

MAX5477/MAX5478/MAX5479

Dual, 256-Tap, Nonvolatile,

C-Interface, Digital Potentiometers

________________________________________________________________

Maxim Integrated Products

19-3379; Rev 5; 11/11

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.

Pin Configurations appear at end of data sheet.

EVALUATION KIT

AVAILABLE

Ordering Information/Selector Guide

PART TEMP RANGE PIN-PACKAGE

END-TO-END

RESISTANCE (k)

TOP MARK

MAX5477ETE+T -40°C to +85°C 16 TQFN-EP* 10 ABO

MAX5477EUD+ -40°C to +85°C 14 TSSOP 10 —

MAX5478ETE+T -40°C to +85°C 16 TQFN-EP* 50 ABP

MAX5478EUD+ -40°C to +85°C 14 TSSOP 50 —

MAX5479ETE+T -40°C to +85°C 16 TQFN-EP* 100 ABQ

MAX5479EUD+ -40°C to +85°C 14 TSSOP 100 —

Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

EP = Exposed pad.

Functional Diagram

MAX5477

MAX5478

MAX5479

8-BIT

SHIFT

POR

16-BIT

LATCH

16-BIT

MEMORY

SDA

SCL

256

POSITION

DECODER

256

POSITION

DECODER

256

GND

INTERFACE

Summary of content (16 pages)

PAGE 1
9-3379; Rev 5; 11/11 KIT ATION EVALU E L B A IL AVA Dual, 256-Tap, Nonvolatile, Digital Potentiometers I2C-Interface, Features o Power-On Recall of Wiper Position from Nonvolatile Memory o EEPROM Write Protection o Tiny 3mm x 3mm x 0.8mm Thin QFN Package o 70ppm/°C End-to-End Resistance Temperature Coefficient o 10ppm/°C Ratiometric Temperature Coefficient o Fast 400kbps I2C-Compatible Serial Interface o 1µA (max) Static Supply Current o Single-Supply Operation: +2.7V to +5.
PAGE 2
MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers ABSOLUTE MAXIMUM RATINGS SDA, SCL, 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_ MAX5477......................................................................±5.0mA MAX5478......................................................................±1.3mA MAX5479.....................
PAGE 3
Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP R0 and R1 set to same code (all codes), VDD = 3V or 5V Dual Code Matching MAX UNITS ±3 LSB 675 DC PERFORMANCE (RESISTOR CHARACTERISTICS) Wiper Resistance RW Wiper Capacitance CW End-to-End Resistance RHL (Note 5) 325 10 pF MAX5477 7.
PAGE 4
MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers TIMING CHARACTERISTICS (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C. See Figure 1.
PAGE 5
Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers SUPPLY CURRENT vs. TEMPERATURE 0.6 VCC = 5V 0.4 VCC = 3V WP = GND VCC = 5V 13 11 9 0.2 7 0 5 VCC = 3V 500 MAX5477/78/79 toc02 SUPPLY CURRENT (µA) 0.8 15 MAX5477/78/79 toc1a WP = VDD SUPPLY CURRENT (µA) MAX5477/78/79 toc01 1.0 WIPER RESISTANCE vs. INPUT CODE 450 400 WIPER RESISTANCE (Ω) SUPPLY CURRENT vs.
PAGE 6
Typical Operating Characteristics (continued) (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) 0.2 MAX5478 0.2 0.1 0.15 0.05 INL (LSB) 0.20 0.10 0 -0.1 -0.2 -0.2 32 64 96 -0.3 0 128 160 192 224 256 32 64 96 0 128 160 192 224 256 32 64 96 128 160 192 224 256 CODE CODE CODE DIFFERENTIAL NONLINEARITY vs. CODE (VDM MODE) INTEGRAL NONLINEARITY vs. CODE (VRM MODE) DIFFERENTIAL NONLINEARITY vs. CODE (VRM MODE) MAX5478 0.2 MAX5478 0.10 0.2 0.04 0.
PAGE 7
Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers 0 -0.04 -20 -40 -50 -60 -30 -40 -50 -60 -0.08 -70 -70 -0.12 -80 -80 -0.16 -90 -90 -0.20 -100 -100 32 64 96 128 160 192 224 256 0.1 1 10 100 1000 FREQUENCY (kHz) CODE CROSSTALK vs. FREQUENCY (MAX5479) -20 CW_ = 10pF 0 -1 GAIN (dB) -50 -60 CW_ = 50pF -3 -4 -2 -3 -4 -6 -7 -7 -100 -8 -8 10 100 1000 10,000 0.1 1 FREQUENCY (kHz) MIDSCALE WIPER RESPONSE vs.
PAGE 8
Typical Operating Characteristics (continued) (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) 0.1 0.01 0.001 0.0001 0.4 0.2 0 -0.2 -0.4 -0.6 0.1 1 10 100 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -15 -40 FREQUENCY (kHz) 10 35 60 -40 85 -15 0.3 0.2 0.1 0 -0.1 -0.2 600 550 500 SUPPLY CURRENT (µA) 0.4 35 SUPPLY CURRENT vs. DIGITAL INPUT VOLTAGE MAX5477/78/79 toc30 0.5 10 TEMPERATURE (°C) TEMPERATURE (°C) END-TO-END RESISTANCE % CHANGE vs.
PAGE 9
Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers PIN NAME FUNCTION TSSOP THIN QFN 1 15 HA Potentiometer A High Terminal 2 14 WA Potentiometer A Wiper Terminal 3 13 LA Potentiometer A Low Terminal 4 12 HB Potentiometer B High Terminal 5 11 WB Potentiometer B Wiper Terminal 6 10 LB Potentiometer B Low Terminal 7 9 WP Write-Protect Input. Connect to GND to allow changes to the wiper position and the data stored in the EEPROM.
PAGE 10
MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers Detailed Description The MAX5477/MAX5478/MAX5479 contain two resistor arrays with 255 elements in each array. The MAX5477 has a total end-to-end resistance of 10kΩ, the MAX5478 has an end-to-end resistance of 50kΩ, and the MAX5479 has an end-to-end resistance of 100kΩ. The MAX5477/MAX5478/MAX5479 provide access to the high, low, and wiper terminals for a standard voltage-divider configuration.
PAGE 11
Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers COMMAND WP = 0 WP = 1 I2C data is written to VREG. Wiper position updates with I2C data. No change to NVREG. Copy NVREG to VREG. Wiper position updates with NVREG data. No change to NVREG. Write to NVREG No change to VREG or wiper position. I2C data is written to NVREG. No change to VREG or wiper position. No change to NVREG. Copy NVREG to VREG Copy NVREG to VREG. Wiper position updates with NVREG data. No change to NVREG.
PAGE 12
MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers register with input shift register data and change the wiper position. Use valid 3-byte I 2C commands for proper operation. This precautionary operation is necessary only when transitioning from write protected (WP = 1) to not write protected (WP = 0). Serial Addressing The MAX5477/MAX5478/MAX5479 operate as slave devices that send and receive data through an I2C-/ SMBus™-compatible 2-wire serial interface.
PAGE 13
Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers SDA MAX5477/MAX5478/MAX5479 CLOCK PULSE FOR ACKNOWLEDGMENT START CONDITION SCL 1 2 8 9 NOT ACKNOWLEDGE SCL SDA DATA STABLE, DATA VALID CHANGE OF DATA ALLOWED ACKNOWLEDGE Figure 5. Bit Transfer Figure 6.
PAGE 14
MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers 5V 5V H_ 30V 30V W_ MAX5477 MAX5478 MAX5479 MAX480 H_ VOUT L_ MAX5477 MAX5478 MAX5479 MAX480 VOUT W_ L_ Figure 9. Positive LCD Bias Control Using a Voltage-Divider VREGxNVREG: Data transfers from the volatile memory register into the nonvolatile memory register. Nonvolatile Memory The internal EEPROM consists of a 16-bit nonvolatile register that retains the value written to it prior to power down.
PAGE 15
Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers V+ VIN R3 C 1/2 MAX5477 WA LA HA MAX5477/MAX5478/MAX5479 5V WA MAX410 LA HA VOUT 7 3 1 8 MAX5477 MAX5478 MAX5479 VR1 2 4 HB R2, R3 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND D = DECIMAL VALUE OF WIPER CODE R2 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND = D DECIMAL VALUE OF WIPER CODE R1 HB WB R2 6 MAX410 1/2 MAX5477 R2 WB LB LB Figure 11. Programmable Filter Figure 12.
PAGE 16
MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers Revision History REVISION NUMBER REVISION DATE DESCRIPTION 0 8/04 Initial release 4 1/09 Updated Ordering Information for lead-free information. 5 11/11 Released TQFN packages, revised Ordering Information. PAGES CHANGED — 1 1–4, 15, 16 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.