MAX5527GUA+T Datasheet MAX5527GTA+T, MAX5529GTA+T, MAX5529GUA+T | P7-P9

MAX5527/MAX5528/MAX5529

Detailed Description

The MAX5527/MAX5528/MAX5529 100kΩ/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.

POTENTIOMETER

CONFIGURATION

VARIABLE-RESISTOR

CONFIGURATION

Figure 1. Potentiometer/Variable-Resistor Configuration

Pin Description

PIN NAME FUNCTION

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

_______________________________________________________________________________________ 7

MAX5527/MAX5528/MAX5529

One-Time Programmable, Linear-Taper Digital

Potentiometers

8 _______________________________________________________________________________________

PV One-Time Programming

The MAX5527/MAX5528/MAX5529 power up and func-

tion after power-up with the wiper position set in one of

three ways:

1) Factory default power-up position, midscale, adjustable

wiper

2) A newly programmed power-up position, adjustable

wiper

3) A new programmed power-up position, locked wiper

The wiper is set to the factory default position at power-

up (midscale, tap 31). Connect PV to GND or leave

floating to continue powering up the wiper position at

midscale. See Table 1 for the default and one-time pro-

gramming options.

U/D

Figure 2. Increment-Mode Timing Diagram

U/D

Figure 3. Decrement-Mode Timing Diagram

U/D

WIPER REMAINS THE

SAME WITH U/D

HIGH AND CS RISING

WIPER CHANGES

WITH U/D LOW AND

CS RISING

Figure 4. CS Low-to-High Transition Timing Diagram

MAX5527/MAX5528/MAX5529

One-Time Programmable, Linear-Taper Digital

Potentiometers

_______________________________________________________________________________________ 9

Change the wiper’s power-up position using the PV

one-time programming sequence after power-up (see

Figure 5). After setting the wiper to the desired power-

up position, perform the following six-step sequence:

1) Set U/D and CS high.

2) Connect an external voltage source at PV in the

range of +11V to +11.55V.

3) Pull CS low.

4a) Pulse CS high for six cycles, consisting of CS

starting low and going high for at least t

CH,

and

then low for at least t

, to change the wiper

power-up position. The wiper remains adjustable.

4b) Pulse CS high for seven cycles, consisting of CS

starting low and going high for at least t

and then

low for at least t

, to change the wiper power-up

position and lock the wiper in that same position.

The seventh CS pulse is labeled the optional lock-

out bit in Figure 5.

5) Connect PV to GND or release the voltage source,

leaving PV floating.

6) Pull CS high.

Pulse CS high for six cycles to change the wiper power-

up position. The wiper position returns to this pro-

grammed position on power-up, but remains adjustable.

Pulse CS high for seven cycles to lock the MAX5527/

MAX5528/MAX5529 to a specific wiper position with no

further adjustments allowed. This effectively converts

the potentiometer to a fixed resistor-divider. The sev-

enth pulse locks the wiper position and disables the

up/down interface. Once locked, connect U/D and CS

high, low, or leave them floating without increasing the

supply current (see Table 1).

If six clock pulses are used, the interface is enabled

and the device can be put into program mode again.

However, the part uses one-time programmable (OTP)

memory and should be programmed only once. If the

part is programmed more than once, all applied values

are ORed together. Thus, if 010101 is programmed the

first time and 101010 is programmed the second time,

the result will be 111111.

The external PV power supply must source at least 5mA

and have a good transient response. Decouple the PV

power supply with a 22µF capacitor to GND. Ensure that

no more than 250µH of inductance and/or 40Ω of para-

sitic resistance exists between the capacitor and the

device (see Figure 6).

+11V

6 PULSES RECORD WIPER POSITION

OPTIONAL 7TH

LOCKOUT BIT

U/D

Figure 5. One-Time Program Mode, Serial-Interface Timing Diagram

11V

22µF

PARASITIC

< 250µH

PARASITIC

< 40Ω

TRACE PARASITICS

MAX5527

MAX5528

MAX5529

Figure 6. PV Power-Supply Decoupling

MODE

POWER-ON RESET

WIPER POSITION

ADJUSTABLE

WIPER

Factory Default

(Unprogrammed)

Tap 31 Yes

Programmed by

Six CS Pulses

Programmed position Yes

Programmed by

Seven CS Pulses

Programmed position No

Table 1. One-Time Programming Options

P1-P3 P4-P6 P7-P9 P10-P12

MAX5527GUA+T

Mfr. #:

Buy MAX5527GUA+T

Manufacturer:

Maxim Integrated

Description:

Digital Potentiometer ICs 64-Tap One-Time Programmable

Lifecycle:

New from this manufacturer.

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MAX5527GUA+T

MAX5527GUA+T

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