Rainbow Electronics MAX5489 User Manual

General Description

The MAX5487/MAX5488/MAX5489 dual, linear-taper,
digital potentiometers function as mechanical poten­tiometers with a simple 3-wire SPI™-compatible digital
interface that programs the wipers to any one of 256
tap positions. These digital potentiometers feature a
nonvolatile memory (EEPROM) to return the wipers to
their previously stored positions upon power-up.

The MAX5487 has an end-to-end resistance of 10kΩ,
while the MAX5488 and MAX5489 have resistances of
50kΩ and 100kΩ, respectively. These devices have a
low 35ppm/°C end-to-end temperature coefficient, and
operate from a single +2.7V to +5.25V supply.

The MAX5487/MAX5488/MAX5489 are available in a
16-pin 3mm x 3mm x 0.8mm thin QFN package. Each
device is guaranteed over the extended -40°C to +85°C
temperature range.

Applications

LCD Screen Adjustment

Audio Volume Control

Mechanical Potentiometer Replacement

Low-Drift Programmable Filters

Low-Drift Programmable-Gain Amplifiers

Features

♦ Wiper Position Stored in Nonvolatile Memory

(EEPROM) and Recalled Upon Power-Up or
Recalled by an Interface Command

♦ 3mm x 3mm x 0.8mm Thin QFN Package

♦ ±1 LSB INL, ±0.5 LSB DNL (Voltage-Divider Mode)

♦ 256 Tap Positions

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

Coefficient

♦ 5ppm/°C Ratiometric Temperature Coefficient

♦ 10kΩ, 50kΩ, and 100kΩ End-to-End Resistance

Values

♦ SPI-Compatible Serial Interface

♦ Reliability

200,000 Wiper Store Cycles
50-Year Wiper Data Retention

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

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,

Linear-Taper Digital Potentiometers

________________________________________________________________ Maxim Integrated Products 1

19-3478; Rev 1; 1/05

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.

SPI is a trademark of Motorola, Inc.

Ordering Information/Selector Guide

PART TEMP RANGE PIN-PACKAGE

END-TO-END

RESISTANCE (kΩ)

TOP MARK

MAX5487ETE* -40°C to +85°C 16 Thin QFN-EP** 10 ABR

MAX5488ETE -40°C to +85°C 16 Thin QFN-EP** 50 ABS

MAX5489ETE -40°C to +85°C 16 Thin QFN-EP** 100 ABT

*Future product—contact factory for availability.
**EP = Exposed pad.

MAX5487
MAX5488
MAX5489

POR

8-BIT

LATCH

16-BIT

NV RAM

SCLK

DIN

CS

DECODER

8

8

256

DECODER

256

HA

WA

LA

HB

WB

LB

V

DD

GND

SPI

INTERFACE

8-BIT

LATCH

Functional Diagram

16

1

2

3

4

12

11

10

9

15 14 13

5678

N.C.

HA

WA

LA

HB

WB

LB

N.C.

SCLK

DIN

N.C.

N.C.

GND

N.C.

V

DD

TOP VIEW

EXPOSED PAD CONNECTED TO GND.

MAX5487
MAX5488
MAX5489

CS

THIN QFN

3mm × 3mm

Pin Configuration

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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.

VDDto GND...........................................................-0.3V to +6.0V

All Other Pins

to GND......................-0.3V to the lower of (V

DD

+ 0.3V) and +6.0V

Maximum Continuous Current into H_, W_, and L_

MAX5487......................................................................±5.0mA

MAX5488......................................................................±1.3mA

MAX5489......................................................................±0.6mA

Continuous Power Dissipation (T

A

= +70°C)

16-Pin Thin QFN (derate 17.5mW/°C above +70°C).....1398mW

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

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-60°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

DC ELECTRICAL CHARACTERISTICS

(VDD= +2.7V to +5.25V, VH= VDD, VL= GND, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= +5.0V,
T

A

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER

CONDITIONS

UNITS

DC PERFORMANCE (Voltage-Divider Mode, Figure 1)

Resolution N

Taps

Integral Nonlinearity INL (Note 2) ±1

LSB

Differential Nonlinearity DNL (Note 2)

LSB

Dual-Code Matching Register A = register B 2

LSB

End-To-End Resistor Tempco TC

R

35

ppm/°C

Ratiometric Resistor Tempco 5

ppm/°C

MAX5488

Full-Scale Error

MAX5489

LSB

MAX5488 0.6 1.5

Zero-Scale Error

MAX5489 0.3 1

LSB

DC PERFORMANCE (Variable-Resistor Mode, Figure 1)

Resolution

Taps

VDD = 5.0V

Integral Nonlinearity (Note 3) MAX5488/MAX5489

V

DD

= 3.0V ±3

VDD = 5.0V ±1

Differential Nonlinearity (Note 3) MAX5488/MAX5489

V

DD

= 3.0V ±1

LSB

DC PERFORMANCE (Resistor Characteristics)

VDD = 5.0V

350

Wiper Resistance (Note 4) R

W

VDD = 3.0V

675

Ω

Wiper Capacitance C

W

50 pF

MAX5487 7.5 10

MAX5488

50

End-to-End Resistance R

HL

MAX5489 75

100

125

kΩ

SYMBOL

MIN TYP MAX

256

±0.5

256

37.5

-0.6 +1.2

-0.3 +1.2

±1.5

200

325

12.5

62.5

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,

Linear-Taper Digital Potentiometers

_______________________________________________________________________________________ 3

DC ELECTRICAL CHARACTERISTICS (continued)

(VDD= +2.7V to +5.25V, VH= VDD, VL= GND, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= +5.0V,
T

A

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER

CONDITIONS

DIGITAL INPUTS

VDD = 3.6V to 5.25V 2.4

Input High Voltage (Note 5) V

IH

VDD = 2.7V to 3.6V

0.7 x

V

Input Low Voltage V

IL

VDD = 2.7V to 5.25V (Note 5) 0.8 V

Input Leakage Current I

IN

µA

Input Capacitance C

IN

5.0 pF

AC PERFORMANCE

Crosstalk

f

H_

= 1kHz, L_ = GND, measurement at W_

(Note 6)

-90 dB

MAX5488 90

-3dB Bandwidth BW

Wiper at midscale
C

W_

= 10pF

MAX5489 45

kHz

Total Harmonic Distortion THD

V

H_

= 1V

RMS

at 1kHz, L_ = GND,

measurement at W_

%

TIMING CHARACTERISTICS (Analog)

MAX5488

Wiper-Settling Time t

S

Code 0 to 127
(Note 7)

MAX5489 1.5

µs

TIMING CHARACTERISTICS (Digital, Figure 2, Note 8)

SCLK Frequency 5

SCLK Clock Period t

CP

ns

SCLK Pulse-Width High t

CH

80 ns

SCLK Pulse-Width Low t

CL

80 ns

CS Fall to SCLK Rise Setup t

CSS

80 ns

SCLK Rise to CS Rise Hold t

CSH

0ns

DIN to SCLK Setup t

DS

50 ns

DIN Hold after SCLK t

DH

0ns

SCLK Rise to CS Fall Delay t

CS0

20 ns

CS Rise to SCLK Rise Hold t

CS1

80 ns

CS Pulse-Width High t

CSW

ns

Write NV Register Busy Time t

BUSY

12 ms

Read NV Register Access Time t

ACC

1µs

W r i te W i p er Reg i ster to O utp ut D el ay

t

WO

1µs

NONVOLATILE MEMORY RELIABILITY

TA = +85°C50

Data Retention

Mil-Std-883 test
method 1008

T

A

= +125°C10

TA = +85°C 200,000

Endurance

Mil-Std-883 test
method 1033

T

A

= +125°C

SYMBOL

MIN TYP MAX UNITS

V

DD

200

200

±1.0

0.02

0.75

50,000

MHz

Years

Stores

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers

4 _______________________________________________________________________________________

Note 1: All devices are production tested at TA= +25°C and are guaranteed by design and characterization for -40°C < TA< +85°C.
Note 2: DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = V

DD

and L_ = 0. The wiper terminal

is unloaded and measured with an ideal voltmeter.

Note 3: DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ = 0. For V

DD

=
+5V, the wiper terminal is driven with a source current of 400µA for the 10kΩ configuration, 80µA for the 50kΩ configuration,
and 40µA for the 100kΩ configuration. For V

DD

= +3V, the wiper terminal is driven with a source current of 200µA for the 10kΩ

configuration, 40µA for the 50kΩ configuration, and 20µA for the 100kΩ configuration.

Note 4: The wiper resistance is the worst value measured by injecting the currents given in Note 3 into W_ with L_ = GND. R

W

=

(V

W

- VH) / IW.

Note 5: The device draws higher supply current when the digital inputs are driven with voltages between (V

DD

- 0.5V) and (GND +

0.5V). See Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics section.

Note 6: Wiper at midscale with a 10pF load.
Note 7: Wiper-settling time is the worst-case 0-to-50% rise time, measured between tap 0 and tap 127. H_ = V

DD

, L_ = GND, and
the wiper terminal is unloaded and measured with a 10pF oscilloscope probe (see Tap-to-Tap Switching Transient in the
Typical Operating Characteristics section).

Note 8: Digital timing is guaranteed by design and characterization, and is not production tested.

DC ELECTRICAL CHARACTERISTICS (continued)

(VDD= +2.7V to +5.25V, VH= VDD, VL= GND, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= +5.0V,
T

A

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

POWER SUPPLIES

Power-Supply Voltage V

DD

V

Supply Current I

DD

During write cycle only, digital inputs =
V

DD

or GND

400 µA

Standby Current Digital inputs = VDD or GND, TA = +25°C 0.5 1 µA

Figure 1. Voltage-Divider/Variable-Resistor Configurations

2.70 5.25

VOLTAGE-DIVIDER

CONFIGURATION

H

L

VARIABLE-RESISTOR

CONFIGURATION

W

H

L

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,

Linear-Taper Digital Potentiometers

_______________________________________________________________________________________ 5

SUPPLY CURRENT vs. TEMPERATURE

MAX5487-89 toc01

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

603510-15

0.2

0.4

0.6

0.8

1.0

1.2

0

-40 85

VCC = 5V

VCC = 3V

SUPPLY CURRENT

vs. DIGITAL INPUT VOLTAGE

MAX5487-89 toc02

DIGITAL INPUT VOLTAGE (V)

SUPPLY CURRENT (µA)

4321

1

10

100

1000

10,000

0

05

VCC = 5V

VCC = 3V

0

100

200

300

400

0 64 128 19232 96 160 224 256

WIPER RESISTANCE

vs. TAP POSITION (MAX5488)

MAX5487-89toc03

TAP POSITION

WIPER RESISTANCE (Ω)

TAP-TO-TAP SWITCHING TRANSIENT

(MAX5488)

MAX5487-89 toc04

1.0µs/div

WIPER

20mV/div

VH_ = 5.0V

CS

2.0V/div

TAP-TO-TAP SWITCHING TRANSIENT

(MAX5489)

MAX5487-89 toc05

1.0µs/div

WIPER

20mV/div

VH_ = 5.0V

CS

2.0V/div

WIPER TRANSIENT AT POWER-ON

MAX5487-89 toc06

2.0µs/div

WIPER

2.0V/div

VH_ = V

DD

V

DD

2.0V/div

Typical Operating Characteristics

(VDD= +5.0V, TA= +25°C, unless otherwise noted.)

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers

6 _______________________________________________________________________________________

VARIABLE-RESISTOR INL

vs. TAP POSITION (MAX5488)

MAx5487-89 toc10

TAP POSITION

INL (LSB)

22419232 64 96 128 160

-0.6

-0.8

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1.0

-1.0
0256

VOLTAGE-DIVIDER DNL

vs. TAP POSITION (MAX5488)

MAx5487-89 toc11

TAP POSITION

DNL (LSB)

22419232 64 96 128 160

-0.15

-0.10

-0.05

0

0.05

0.10

0.15

0.20

-0.20

0256

VOLTAGE-DIVIDER INL

vs. TAP POSITION (MAX5488)

MAx5487-89 toc12

TAP POSITION

INL (LSB)

22419232 64 96 128 160

-0.6

-0.8

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1.0

-1.0
0256

Typical Operating Characteristics (continued)

(VDD= +5.0V, TA= +25°C, unless otherwise noted.)

MIDSCALE FREQUENCY RESPONSE

(MAX5488)

MAX5487-89 toc07

FREQUENCY (kHz)

GAIN (dB)

100101

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

-50

0.1 1000

CW_ = 10pF

CW_ = 50pF

MIDSCALE FREQUENCY RESPONSE

(MAX5489)

MAX5487-89 toc08

FREQUENCY (kHz)

GAIN (dB)

100101

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

-50

0.1 1000

CW_ = 10pF

CW_ = 50pF

VARIABLE-RESISTOR DNL

vs. TAP POSITION (MAX5488)

MAx5487-89 toc09

TAP POSITION

DNL (LSB)

22419232 64 96 128 160

-0.15

-0.10

-0.05

0

0.05

0.10

0.15

0.20

-0.20
0256

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,

Linear-Taper Digital Potentiometers

_______________________________________________________________________________________ 7

VARIABLE-RESISTOR DNL

vs. TAP POSITION (MAX5489)

MAx5487-89 toc13

TAP POSITION

DNL (LSB)

22419232 64 96 128 160

-0.15

-0.10

-0.05

0

0.05

0.10

0.15

0.20

-0.20
0256

VOLTAGE-DIVIDER INL

vs. TAP POSITION (MAX5489)

MAx5487-89 toc16

TAP POSITION

INL (LSB)

22419232 64 96 128 160

-0.6

-0.8

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1.0

-1.0
0 256

VARIABLE-RESISTOR INL

vs. TAP POSITION (MAX5489)

MAx5487-89 toc14

TAP POSITION

INL (LSB)

22419232 64 96 128 160

-0.6

-0.8

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1.0

-1.0
0256

VOLTAGE-DIVIDER DNL

vs. TAP POSITION (MAX5489)

MAx5487-89 toc15

TAP POSITION

DNL (LSB)

22419232 64 96 128 160

-0.15

-0.10

-0.05

0

0.05

0.10

0.15

0.20

-0.20
0 256

-30

-100

0.1 1 100 1000

CROSSTALK vs. FREQUENCY

-90

-70

-50

-80

-60

-40

MAX5487-89toc17

FREQUENCY (kHz)

CROSSTALK (dB)

10

CW_ = 10pF

MAX5489

MAX5488

-0.010

-0.004

-0.006

-0.008

-0.002

0

0.002

0.004

0.006

0.008

0.010

-40 10-15 35 60 85

END-TO-END RESISTANCE CHANGE

vs. TEMPERATURE (MAX5488)

MAX5487-89 toc18

TEMPERATURE (°C)

RESISTANCE CHANGE (%)

-0.010

-0.004

-0.006

-0.008

-0.002

0

0.002

0.004

0.006

0.008

0.010

-40 10-15 35 60 85

END-TO-END RESISTANCE CHANGE

vs. TEMPERATURE (MAX5489)

MAX5487-89 toc19

TEMPERATURE (°C)

RESISTANCE CHANGE (%)

Typical Operating Characteristics (continued)

(VDD= +5.0V, TA= +25°C, unless otherwise noted.)

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers

8 _______________________________________________________________________________________

Detailed Description

The MAX5487/MAX5488/MAX5489 contain two resistor
arrays, with 255 resistive elements each. The MAX5487
has an end-to-end resistance of 10kΩ, while the
MAX5488 and MAX5489 have resistances of 50kΩ and
100kΩ, respectively. The MAX5487/MAX5488/MAX5489
allow access to the high, low, and wiper terminals on
both potentiometers for a standard voltage-divider con­figuration. Connect the wiper to the high terminal, and
connect the low terminal to ground, to make the device
a variable resistor (see Figure 1).

A simple 3-wire serial interface programs either wiper
directly to any of the 256 tap points. The nonvolatile
memory stores the wiper position prior to power-down
and recalls the wiper to the same point upon power-up
or by using an interface command (see Table 1). The
nonvolatile memory is guaranteed for 200,000 wiper
store cycles and 50 years for wiper data retention.

SPI Digital Interface

The MAX5487/MAX5488/MAX5489 use a 3-wire SPI­compatible serial data interface (Figures 2 and 3). This
write-only interface contains three inputs: chip-select

(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, address, and data
(Figure 3a). The COPY commands (C1, C0 = 10, 11) can
use either eight clock cycles to transfer only command
and address bits (Figure 3b) or 16 clock cycles, with the
device disregarding 8 data bits (Figure 3a).

After loading data into the shift register, drive CS high
to latch the data into the appropriate potentiometer
control register and disable the serial interface. Keep
CS low during the entire serial data stream to avoid cor­ruption of the data.

Digital-Interface Format

The data format consists of three elements: command
bits, address bits, and data bits (see Table 1 and
Figure 3). The command bits (C1 and C0) indicate the
action to be taken such as changing or storing the
wiper position. The address bits (A1 and A0) specify
which potentiometer the command affects and the 8
data bits (D7 to D0) specify the wiper position.

PIN NAME FUNCTION

1VDDPower Supply. Bypass to GND with a 0.1µF capacitor as close to the device as possible.

2 SCLK Serial-Interface Clock Input

3 DIN Serial-Interface Data Input

4 CS Active-Low Chip-Select Digital Input

5, 6, 8, 9, 16

N.C. No Connection. Not internally connected.

7 GND Ground

10 LB

Low Terminal of Resistor B. The voltage at L can be greater than or less than the voltage at H.
Current can flow into or out of L.

11 WB Wiper Terminal of Resistor B

12 HB

High Terminal of Resistor B. The voltage at H can be greater than or less than the voltage at L.
Current can flow into or out of H.

13 LA

Low Terminal of Resistor A. The voltage at L can be greater than or less than the voltage at H.
Current can flow into or out of L.

14 WA Wiper Terminal of Resistor A

15 HA

High Terminal of Resistor A. The voltage at H can be greater than or less than the voltage at L.
Current can flow into or out of H.

— E.P. Exposed Pad. Not internally connected. Connect to ground or leave floating.

Pin Description

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,

Linear-Taper Digital Potentiometers

_______________________________________________________________________________________ 9

Write-Wiper Register (Command 00)

Data written to the write-wiper registers (C1, C0 = 00)
controls the wiper positions. The 8 data bits (D7 to D0)
indicate the position of the wiper. For example, if DIN =
0000 0000, the wiper moves to the position closest to
L_. If DIN = 1111 1111, the wiper moves closest to H_.

This command writes data to the volatile RAM, leaving the
NV registers unchanged. When the device powers up,
the data stored in the NV registers transfers to the volatile
wiper register, moving the wiper to the stored position.

Write-NV Register (Command 01)

This 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 can be used to store the position of the
wipers to the NV registers. Writing to the NV registers,
does not affect the position of the wipers.

Copy Wiper Register to NV Register (Command 10)

This command (C1, C0 = 10) stores the current position
of the wiper to the NV register, for use at power-up.

Table 1. Register Map

123456789101112131415

16

CLOCK EDGE

D0

Write Wiper Register A

D0

Write Wiper Register B

D0

Write NV Register A

D0

Write NV Register B

D0

Copy Wiper Register A to NV
Register A

—

Copy Wiper Register B to NV
Register B

—

Copy Both Wiper Registers to
NV Registers

—

Copy NV Register A to Wiper
Register A

—

Copy NV Register B to Wiper
Register B

—

Copy Both NV Registers to
Wiper Registers

—

Figure 2. Timing Diagram

CS

t

CSO

t

CSS

t

CL

t

CH

t

DH

t

DS

t

CP

t

CSH

t

CSW

t

CS1

SCLK

DIN

——C1 C0 ——A1 A0 D7 D6 D5 D4 D3 D2 D1

00000001D7D6D5D4D3D2D1

00000010D7D6D5D4D3D2D1

00010001D7D6D5D4D3D2D1

00010010D7D6D5D4D3D2D1

00100001———————

00100010———————

00100011———————

00110001———————

00110010———————

00110011———————

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers

10 ______________________________________________________________________________________

This command may affect one potentiometer at a time,
or both simultaneously, depending on the state of A1
and A0. Alternatively, the “write NV register” command
can be used to store the current position of the wiper to
the NV register.

Copy NV Register to Wiper Register (Command 11)

This command (C1, C0 = 11) restores the wiper position
to the previously stored position in the NV register. This
command may affect one potentiometer at a time, or both
simultaneously, depending on the state of A1 and A0.

Nonvolatile Memory

The internal EEPROM consists of a nonvolatile register
that retains the last stored value prior to power-down.
The nonvolatile register is programmed to midscale at
the factory. The nonvolatile memory is guaranteed for
200,000 wiper write cycles and 50 years for wiper data
retention.

Power-Up

Upon power-up, the MAX5487/MAX5488/MAX5489
load the data stored in the nonvolatile wiper register
into the volatile memory register, updating the wiper
position with the data stored in the nonvolatile wiper
register. This initialization period takes 5µs.

Standby

The MAX5487/MAX5488/MAX5489 feature a low-power
standby mode. When the device is not being pro­grammed, it enters into standby mode and supply cur­rent drops to 0.5µA (typ).

Applications Information

The MAX5487/MAX5488/MAX5489 are ideal for circuits
requiring digitally controlled adjustable resistance,
such as LCD contrast control (where voltage biasing
adjusts the display contrast), or for programmable fil­ters with adjustable gain and/or cutoff frequency.

Positive LCD Bias Control

Figures 4 and 5 show an application where the
MAX5487/MAX5488/MAX5489 provide an adjustable,
positive LCD-bias voltage. The op amp provides buffer­ing and gain to the resistor-divider network made by
the potentiometer (Figure 4) or by a fixed resistor and a
variable resistor (Figure 5).

Programmable Filter

Figure 6 shows the MAX5487/MAX5488/MAX5489 in a
1st-order programmable-filter application. Adjust the gain
of the filter with R2, and set the cutoff frequency with R3.

Figure 3. Digital-Interface Format

16151413121110987654321

SCLK

C1 C0

D7 D6 D5 D4 D3 D2 D1 D0A1 A0

87654321

C1 C0

A1 A0

DIN

SCLK

CS

B) 8-BIT COMMAND WORD

A) 16-BIT COMMAND/DATA WORD

CS

DIN

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,

Linear-Taper Digital Potentiometers

______________________________________________________________________________________ 11

Use the following equations to calculate the gain (A)
and the -3dB cutoff frequency (fC):

Adjustable Voltage Reference

Figure 7 shows the MAX5487/MAX5488/MAX5489 used
as the feedback resistors in multiple adjustable volt­age-reference applications. Independently adjust the
output voltages of the MAX6160s from 1.23V to VIN-

0.2V by changing the wiper positions of the MAX5487/
MAX5488/MAX5489.

Offset Voltage and Gain Adjustment

Connect the high and low terminals of one potentiome­ter of a MAX5487/MAX5488/MAX5489 to the NULL
inputs of a MAX410, and connect the wiper to the op
amp’s positive supply to nullify the offset voltage over
the operating temperature range. Install the other
potentiometer in the feedback path to adjust the gain of
the MAX410 (see Figure 8).

Chip Information

TRANSISTOR COUNT: 12,177

PROCESS: BiCMOS

f

RC

C

=

××

1

2

3

π

A

R

R

=+

1

1

2

Figure 4. Positive LCD-Bias Control Using a Voltage-Divider

V

OUT

30V

5V

W_

H_

L_

MAX5487
MAX5488
MAX5489

MAX480

Figure 5. Positive LCD-Bias Control Using a Variable Resistor

V

OUT

30V

5V

W_

H_

L_

MAX5487
MAX5488
MAX5489

MAX480

Figure 6. Programmable Filter

1/2 MAX5487
1/2 MAX5488
1/2 MAX5489

1/2 MAX5487
1/2 MAX5488
1/2 MAX5489

V

IN

R

2

HB

WB

LB

R

1

V

OUT

R

3

HA

WA

LA

C

MAX410

V+

V-

R

2

, R3 = RHL x D / 256

WHERE R

HL

= END-TO-END RESISTANCE

AND D = DECIMAL VALUE OF WIPER CODE

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers

12 ______________________________________________________________________________________

Figure 7. Adjustable Voltage Reference

MAX6160

IN

5V

OUT

ADJ

GND

HA

LA

WA

V

OUT1

IN

OUT

ADJ

GND

HB

LB

WB

V

OUT2

1/2 MAX5487
1/2 MAX5488
1/2 MAX5489

MAX6160

1/2 MAX5487
1/2 MAX5488
1/2 MAX5489

FOR THE MAX5487

V

OUT_

= 1.23V x

10kΩ

R

FOR THE MAX5488

V

OUT_

= 1.23V x

50kΩ

R

FOR THE MAX5489

V

OUT_

= 1.23V x

100kΩ

R

R2 = RHL x D / 256
WHERE R

HL

= END-TO-END RESISTANCE

AND D = DECIMAL VALUE OF WIPER CODE

RR

Figure 8. Offset Voltage and Gain Adjustment

3

2

5V

7

4

1

6

8

MAX410

HA

LA

WA

R2

R1

HB

LB

WB

1/2 MAX5487/MAX5488/MAX5489

1/2 MAX5487/MAX5488/MAX5489

R2 = RHL x D / 256
WHERE R

HL

= END-TO-END RESISTANCE

AND = D DECIMAL VALUE OF WIPER CODE

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,

Linear-Taper Digital Potentiometers

______________________________________________________________________________________ 13

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

12x16L QFN THIN.EPS

0.10 C 0.08 C

0.10 M C A B

D

D/2

E/2

E

A1

A2

A

E2

E2/2

L

k

e

(ND - 1) X e

(NE - 1) X e

D2

D2/2

b

L

e

L

C

L

e

C

L

L

C

L

C

E

1

2

21-0136

PACKAGE OUTLINE
12, 16L, THIN QFN, 3x3x0.8mm

MAX5487/MAX5488/MAX5489

Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers

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.

14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.

EXPOSED PAD VARIATIONS

2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.

3. N IS THE TOTAL NUMBER OF TERMINALS.

4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO
JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED
WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE.

5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm
FROM TERMINAL TIP.

6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.

7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.

8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.

9. DRAWING CONFORMS TO JEDEC MO220 REVISION C.

NOTES:

E

2

2

21-0136

PACKAGE OUTLINE
12, 16L, THIN QFN, 3x3x0.8mm

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