MAX5427EUA+T Datasheet MAX5429EUA, MAX5429EUA+T, MAX5429ETA+T | P4-P6

MAX5427/MAX5428/MAX5429

One-Time Programmable, Linear-Taper

Digital Potentiometers

4 _______________________________________________________________________________________

Typical Operating Characteristics

= 5.0V, T

= +25°C, unless otherwise noted.)

WIPER RESISTANCE vs. WIPER VOLTAGE

MAX5427 toc01

WIPER VOLTAGE (V)

WIPER RESISTANCE (Ω)

4321

100

120

140

160

= 3.3V

= 5.0V

END-TO-END RESISTANCE PERCENT

CHANGE vs. TEMPERATURE

MAX5427-29 toc02

TEMPERATURE (°C)

END-TO-END RESISTANCE CHANGE (%)

603510-15

-0.2

-0.1

0.1

0.2

0.3

-0.3

-40 85

MAX5429

MAX5428

MAX5427

W-TO-L RESISTANCE

vs. TAP POSITION

MAX5427-29 toc03

TAP POSITION

W-TO-L RESISTANCE (kΩ)

252015105

100

030

MAX5427

MAX5428

MAX5429

SUPPLY CURRENT vs. TEMPERATURE

MAX5427-29 toc04

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

603510-15

0.05

0.10

0.15

0.20

0.25

0.30

-40 85

= 5.0V

= 3.3V

R-DNL ERROR vs. INPUT CODE

(MAX5427)

MAX5427-29 toc07

INPUT CODE (DECIMAL)

R-DNL (LSB)

252051015

-0.015

-0.010

-0.005

0.005

0.010

0.015

0.020

-0.020

030

R-INL ERROR vs. INPUT CODE

(MAX5427)

MAX5427-29 toc08

INPUT CODE (DECIMAL)

R-INL (LSB)

252015105

-0.08

-0.06

-0.04

-0.02

0.02

0.04

0.06

0.08

0.10

-0.10

030

R-DNL ERROR vs. INPUT CODE

(MAX5428)

MAX5427-29 toc09

INPUT CODE (DECIMAL)

R-DNL (LSB)

252051015

-0.015

-0.010

-0.005

0.005

0.010

0.015

0.020

-0.020

030

TAP-TO-TAP SWITCHING TRANSIENT

MAX5427-29 toc05

100ns/div

OUTPUT

100mV/div

U/D

2V/div

= 10pF

WIPER TRANSIENT AT POWER-ON

MAX5427-29 toc06

s/div

OUTPUT

1V/div

2V/div

Detailed Description

The MAX5427/MAX5428/MAX5429 are 100kΩ/50kΩ/

10kΩ (end-to-end resistance) digitally controlled poten-

tiometers. They have 32 tap positions that are accessible

to the wiper along the resistor array between H and L.

The wiper (W) position is adjusted sequentially through

the tap positions using a simple 2-wire interface. These

digital potentiometers have an optional one-time pro-

grammable feature that sets the POR position of the

wiper. The 2-wire interface can then be disabled, perma-

nently preventing unwanted adjustment.

Digital Interface Operation

The MAX5427/MAX5428/MAX5429 have two modes of

operation when the serial interface is active: increment

mode and 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. When CS transitions from high

to low, the part goes into increment mode if U/D is high

(Figure 2), and into decrement mode if U/D is low

(Figure 3). Once the mode is set, the device remains in

that mode until CS goes high. A low-to-high transition at

the U/D increments or decrements the wiper position

depending on the current mode.

When the CS input transitions to high (when serial inter-

face is inactive) and U/D is low, the wiper increments or

decrements one position in accordance with the state

of U/D when CS went low. If U/D is high when CS tran-

sitions to high, the wiper remains in the same position.

MAX5427/MAX5428/MAX5429

One-Time Programmable, Linear-Taper

Digital Potentiometers

_______________________________________________________________________________________ 5

Pin Description

Typical Operating Characteristics (continued)

= 5.0V, T

= +25°C, unless otherwise noted.)

R-INL ERROR vs. INPUT CODE

(MAX5428)

MAX5427-29 toc10

INPUT CODE (DECIMAL)

R-INL (LSB)

252015105

-0.08

-0.06

-0.04

-0.02

0.02

0.04

0.06

0.08

0.10

-0.10

030

R-DNL ERROR vs. INPUT CODE

(MAX5429)

MAX5427-29 toc11

INPUT CODE (DECIMAL)

R-DNL (LSB)

252015105

-0.020

-0.015

-0.010

-0.005

0.005

0.010

0.015

0.020

0.025

-0.025

030

R-INL ERROR vs. INPUT CODE

(MAX5429)

MAX5427-29 toc12

INPUT CODE (DECIMAL)

R-INL (LSB)

252015105

-0.08

-0.06

-0.04

-0.02

0.02

0.04

0.06

0.08

0.10

-0.10

030

PIN NAME FUNCTION

1 W Wiper Connection

2 CS

Chip-Select Input. A high-to-low CS transition determines the mode: increment if U/D is high, or

decrement if U/D is low. CS is also used for one-time programming (see the One-Time Programming

section).

Power-Supply Voltage

4 GND Ground

Programming Voltage for One-Time Programming. Connect V

to 10V supply when one-time

programming the device. For normal operation, connect to ground or let float.

6U/D

Up/Down Control Input. With CS low, a low-to-high transition increments or decrements the wiper

position.

7 L Low Terminal of Resistor

8 H High Terminal of Resistor

MAX5427/MAX5428/MAX5429

The value of the counter is then stored and the wiper

position is maintained.

The wiper performs a make-before-break transition,

ensuring that there is never an open circuit during a tran-

sition from one resistor tap to another. When the wiper is

at either end (max/min) of the resistor array, additional

transitions in the direction of the endpoint do not change

the counter value (the counter does not wrap around).

One-Time Programming

The factory-set default position of the wiper on power-

up is tap 16. However, the power-up position can be

changed once using the one-time programming fea-

ture. After the wiper is moved to the desired position,

the programming sequence is initiated by setting U/D

high, applying 11V to V

, and then taking CS low. Five

pulses on CS (consisting of CS starting from low and

going high for t

and then low for t

) program the

device (Figure 4). The programming voltage should

then be taken to zero. After the device is programmed,

can be set to zero or be allowed to float. The wiper

position is still adjustable, but always returns to this

programmed position on power-up.

If the intent is to program the device to a specific wiper

position and not to allow further adjustments, then six

programming pulses are required (as opposed to five),

as shown in Figure 4. The sixth pulse locks the wiper

position and disables the serial interface. This also

allows U/D and CS to float without any increase in sup-

ply current. Once the lockout bit is set, no further

adjustment to the potentiometer is possible, effectively

changing the potentiometer into a fixed resistor-divider

(Table 1).

One-Time Programmable, Linear-Taper

Digital Potentiometers

6 _______________________________________________________________________________________

U/D

Figure 2. Increment Mode Serial Interface Timing Diagram

U/D

Figure 3. Decrement Mode Serial Interface Timing Diagram

MODE

POWER-ON

RESET WIPER

POSITION

ADJUSTABLE

WIPER

Factory Default

(Unprogrammed)

Tap 16 Yes

Programmed

(5 Programming Pulses)

Programmed

position

Yes

Lock-Bit Set

(6 Programming Pulses)

Programmed

position

Table 1. One-Time Programming Options

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

MAX5427EUA+T

Mfr. #:

Buy MAX5427EUA+T

Manufacturer:

Maxim Integrated

Description:

Digital Potentiometer ICs 32-Tap One-Time Programmable

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MAX5427EUA+T

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