Detailed Description

The MAX5527/MAX5528/MAX5529 100k

Ω/50kΩ/10kΩ

end-to-end resistance digitally-controlled potentiome-

ters offer 64 wiper tap positions accessible along the

resistor array between H and L. These devices function

as potentiometers or variable resistors (see Figure 1).

The wiper (W) position is adjusted sequentially through

the tap positions using a simple 2-wire up/down inter-

face. These digital potentiometers provide an optional

one-time programmable feature that sets and locks the

power-on reset position of the wiper (see the

PV One-

Time Programming section). Once the desired wiper

position is programmed, the 2-wire interface can be

disabled to prevent unwanted adjustment.

Digital Interface Operation

The MAX5527/MAX5528/MAX5529 provide two modes

of operation when the serial interface is active: incre-

ment mode or decrement mode. The serial interface is

only active when

CS is low.

The

CS and U/D inputs control the position of the wiper

along the resistor array. Set U/

D high to increment the

MAX5527/MAX5528/MAX5529 when

CS transitions

from high to low (Figure 2). Set U/

D low to decrement

the MAX5527/MAX5528/MAX5529 when

CS transitions

high to low (Figure 3). Once

CS is held low, each low-

to-high transition at U/

D increments or decrements the

wiper one position. Once the increment or decrement

mode is set, the device remains in that mode until

CS

goes high.

Idle U/

D high for normal operation. If U/D is low when

CS transitions low to high, the wiper moves one addi-

tional tap in its present direction. The wiper remains in

the same position when U/

D is high and CS transitions

low to high. After

CS returns high, the wiper position

remains the same (Figure 4).

Additional increments do not change the wiper position

when the wiper is at the maximum end of the resistor

array. Additional decrements do not change the wiper

position when the wiper is at the minimum end of the

resistor array.

H

L

H

L

W

POTENTIOMETER

CONFIGURATION

VARIABLE-RESISTOR

CONFIGURATION

W

Figure 1. Potentiometer/Variable-Resistor Configuration

Pin Description

PIN

NAME

DESCRIPTION

1

W

Wiper Connection

2

CS

Chip-Select Input. A high-to-low

CS transition determines the increment/decrement mode. Increment

if U/

D is high, or decrement if U/D is low. CS is also used for one-time programming. See the PV One-

Time Programming section.

Supply Voltage. Bypass with a 0.1µF capacitor to GND.

4

GND

Ground

5PV

One-Time Programming Voltage. Connect PV to an 11V supply at the time the device is

programmed/locked, and bypass with a 22µF capacitor to GND. For normal operation, connect to

GND or leave floating.

6U/

D

Up/Down Control Input. When

CS is low, a low-to-high transition at U/D increments or decrements the

wiper position. See the Digital Interface Operation section.

7

L

Resistor Low Terminal

8

H

Resistor High Terminal

—EP

Exposed Pad (TDFN Only). Internally connected to GND. Connect to a large ground plane to

maximize thermal dissipation.

One-Time Programmable, Linear-Taper Digital

Potentiometers

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