MAX5474 MAXIM [Maxim Integrated Products], MAX5474 Datasheet - Page 4

• Manufacturer Part Number: MAX5474
• Description: MAX5474 Evaluation Kit
• Manufacturer: MAXIM [Maxim Integrated Products]

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.
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.
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.
MAX5474 Evaluation Kit
Table 2. JU2, JU3, JU4 Jumper Functions (CS, U/D, INC)
* Default position.
4
Detailed Description of Hardware
POSITION
_______________________________________________________________________________________
Programming Nonvolatile (NV) Memory in Stand-
SHUNT
Open
1-3*
1-2
1-4
SIGNALS CONNECTED TO
INTERFACE CONTROL
USB interface circuit
No connect
PCB pads
Switches
Nonvolatile Memory
Software Operation
Alone Operation
User-supplied external signals (EV kit software not updated)
USB interface circuit and EV kit software
S tand - al one op er ati on, sw i tches S W 1, S W 2, S W 3 ( E V ki t softw ar e not up d ated ) :
• SW1 controls the CS signal
• SW2 controls the U/D signal
• SW3 controls the INC signal
Do not use this configuration
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.
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 1. JU1 Jumper Functions (V
* Default position.
INTERFACE SIGNALS CONTROLLED BY
POSITION
SHUNT
Open
1-2*
2-3
CONNECTED TO
Jumper and Switch Functions
Using an External DC Power Supply
No connect
V
DD
3.3V
VIN
PIN
Interface Control Signals
Do not use (EV kit will not
External power supply
USB interface circuit
EV KIT POWERED
be powered)
FROM
DD
)