MAX17633 datasheet(3/14 Pages) MAXIM

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Evaluates: MAX17633

3.3V Output-Voltage Application

MAX17633AEVKIT# Evaluation Kit

MODE Selection (MODE/SYNC)

The device’s MODE/SYNC pin can be used to select

among forced PWM, DCM, or PFM modes of operation

at light loads. The logic state of the MODE/SYNC pin is

latched when the VCC and EN/UVLO voltages exceed

the respective UVLO rising thresholds and all internal volt-

ages are ready to allow LX switching. State changes on

the MODE/SYNC pin are ignored during normal operation.

Refer to the MAX17633 IC datasheet for more information

on the PWM, DCM, and PFM modes of operation. Table 2

shows the EV kit jumper (JU2) settings that can be used to

configure the desired mode of operation.

External Clock Synchronization

(MODE/SYNC)

The internal oscillator of the MAX17633A can be

synchronized to an external clock signal through the

MODE/ SYNC pin in DCM and PWM modes of operation.

The synchronization to an external clock is not supported

in PFM mode of operation. The external synchronization

clock frequency must be between 1.1 x fSW and 1.4 x

fSW, where fSW is the frequency of operation as set by

R5 resistor. The minimum external clock high pulse width

should be greater than 50ns and minimum external low

pulse width should be greater than 160ns. The source

impedance of the external SYNC signal source should be

below 25kΩ for reliable operation.

Hot Plug-In and Long Input Cables

The MAX17633AEVKIT# PCB layout provides an optional

electrolytic capacitor (C6, 10μF/50V). This capacitor limits

the peak voltage at the input of the MAX17633A when

the DC input source is “Hot-Plugged” to the EV kit input

terminals with long input cables. The equivalent series

resistance (ESR) of the electrolytic capacitor dampens

the oscillations caused by interaction of the inductance of

the long input cables, and the ceramic capacitors at the

power module input.

Table 2. MODE/SYNC Description (JU2)

*Default position

SHUNT

POSITION

MODE/SYNC PIN

MAX17633A EV KIT

OUTPUT

1-2

Connected to INTVCC

DCM mode of

operation

2-3*

Connected to SGND

PWM mode of

operation

Not

Installed

Unconnected

PFM model of

operation

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