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MAX5474EVKIT

MAX5474 Evaluation Kit

Maxim Integrated 

MAX5474 Evaluation Kit

Detailed Description of Hardware

The MAX5474 EV kit demonstrates the MAX5474, a 32-

tap, 50kΩ nonvolatile, linear-taper digital potentiometer

IC’s features. The EV kit uses a MAX5474 IC in an 8-pin

SOT23 package on a proven two-layer PCB design. The

MAX5474 EV kit provides two options to power the

MAX5474 IC. It can operate from the 3.3V supply gener-

ated from the USB interface circuit, or from a user-sup-

plied 2.7V to 5.25V external DC power supply. The USB

interface circuit features MAX3374 low-voltage logic-

level translators (U7 and U8) for 2.7V to 5.25V operation.

Nonvolatile Memory

Programming Nonvolatile (NV) Memory in Stand-

Alone Operation

In stand-alone operation, the MAX5474 wiper position

is stored in nonvolatile memory whenever the SPDT

slide switch SW1 (CS) is moved from EN to DIS (rising

edge) and the pushbutton switch SW3 (INC) is not

depressed (high). The wiper returns to this stored posi-

tion upon power-up.

Software Operation

In software operation, the MAX5474 wiper position is

stored in nonvolatile memory when the Store button is

pressed. The MAX5474 wiper returns to this position

upon power-up. After powering up the EV kit, before

changing the wiper position from the nonvolatile memo-

ry position, press the Reset button to reinitialize the

wiper to a known position (midscale). Reset does not

overwrite the MAX5474 nonvolatile memory; press the

Factory Default button to reset the NV memory to the

factory-preset position (midscale). See the Detailed

Description of Software section for more information.

Jumper and Switch Functions

Using an External DC Power Supply

The MAX5474 EV kit can be powered by an external

2.7V to 5.25V DC power supply. To connect the EV kit

to an external power supply, disconnect the USB cable

and install a shunt on pins 2-3 of jumper JU1. Turn off

the power supply and connect the power-supply

ground terminal to the EV kit GND pad and the power-

supply positive terminal to the VIN pad. Table 1 lists the

various options for powering the MAX5474 EV kit.

Table 1. JU1 Jumper Functions (VDD)

SHUNT

VDD PIN

POSITION CONNECTED TO

EV KIT POWERED

FROM

1-2*

3.3V

USB interface circuit

Open

No connect

Do not use (EV kit will not

be powered)

2-3

VIN

*Default position.

External power supply

Interface Control Signals

The MAX5474 EV kit circuit features three logic-input

signals to control the MAX5474 wiper position. The

chip-select (CS), up/down (U/D), and increment (INC)

interface signals are controlled by the on-board USB

interface circuit or the PCB pads, along with user-sup-

plied external control signals, or stand-alone operation

using switches on the EV kit. Jumpers JU2, JU3, and

JU4 select the interface-signal-control sources for the

MAX5474 IC. Table 2 lists the various options for con-

figuring logic-input signal controls.

Table 2. JU2, JU3, JU4 Jumper Functions (CS, U/D, INC)

SHUNT

POSITION

1-2

1-3*

1-4

Open

*Default position.

INTERFACE CONTROL

SIGNALS CONNECTED TO

PCB pads

USB interface circuit

Switches

No connect

INTERFACE SIGNALS CONTROLLED BY

User-supplied external signals (EV kit software not updated)

USB interface circuit and EV kit software

Stand-alone operation, switches SW1, SW2, SW3 (EV kit software not updated):

• SW1 controls the CS signal

• SW2 controls the U/D signal

• SW3 controls the INC signal

Do not use this configuration

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