MAX5128 Просмотр технического описания (PDF) - Maxim Integrated

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MAX5128

128-Tap, Nonvolatile, Linear-Taper Digital Potentiometer in 2mm x 2mm µDFN Package

Maxim Integrated 

128-Tap, Nonvolatile, Linear-Taper Digital

Potentiometer in 2mm x 2mm µDFN Package

tIMMU

UP

tIMMU

DN

tIMMU

PULSES WITH WIDTHS LESS THAN tIMMU ARE IGNORED.

tIMMU

Figure 4. Glitch-Immunity Timing Diagram

Standby Mode

The MAX5128 operates in standby mode while the seri-

al interface is inactive. Programming the MAX5128

increases the average operating current to 400µA

(max). When in standby mode, the static supply current

reduces to less than 0.5µA (typ).

Power-Up

Upon power-up, the MAX5128 updates the wiper posi-

tion with the data stored in the nonvolatile memory. This

initialization period takes 2µs (typ). For proper opera-

tion, limit the supply voltage slew rate to ≥ 10µs.

Applications Information

Use the MAX5128 for applications requiring digitally

controlled adjustable resistance or voltage, such as

LCD contrast control (where voltage biasing adjusts the

display contrast), or DC-DC converters with adjustable

outputs. The 22kΩ end-to-end resistance is divided into

128 tap points of 172Ω each. Use the MAX5128 in a

voltage-divider or variable-resistor configuration.

VCOM Generator

Figure 5 shows an application using the MAX4238 and

the MAX5128 to generate the VCOM voltage for a LCD

panel. Adjusting the resistor value of the MAX5128

changes the VCOM voltage. Adjusting the VCOM volt-

age changes the contrast for the LCD panel.

DC-DC Converter Applications

Figures 6 and 7 show two applications using the

MAX5128 to adjust the output voltage of a DC-DC con-

verter. Figure 6 shows the MAX5128 in the grounded

potentiometer configuration. Figure 7 shows the

MAX5128 in a floating potentiometer configuration. The

grounded potentiometer configuration forces the output

voltage range of the DC-DC converter to fall within the

supply voltage range of the MAX5128. Use the floating

potentiometer configuration to allow the DC-DC con-

verter’s output to exceed the supply voltage range of

the MAX5128. The floating potentiometer configuration

increases the output voltage range and increases the

precision of the output voltage adjustment range.

LED Bias Adjustment

Figure 8 shows a LED bias adjustment application

using a MAX5128 to set the current of the LEDs that the

MAX1574 drives. Use the MAX5128 for an adjustable

LED current drive of 10mA to 60mA.

Chip Information

PROCESS: BiCMOS

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