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Evaluates: MAX17536

3.3V Output-Voltage Application

MAX17536EVKITA#

Evaluation Kit

Detailed Description

The MAX17536 EV kit provides a proven design to

evaluate the high-voltage, high-efficiency, synchronous

step-down DC-DC converter. The EV kit is preset for a

3.3V output from a 4.5V to 60V input at load currents of

up to 4A and features a 450kHz switching frequency for

optimum efficiency and component size.

The EV kit includes an EN/UVLO PCB pad and JU1 to

enable the output at the desired input voltage. The SYNC

PCB pad allows an external clock to synchronize the

device. JU2 allows the selection of a particular mode of

operation based on light-load performance requirements.

An additional RESET PCB pad is available for monitoring

whether the converter output is in regulation.

Soft-Start Input (SS)

The device utilizes an adjustable soft-start function to

limit inrush current during startup. The soft-start time is

adjusted by the value of the external capacitor from SS to

C7, as shown by the following equation:

equation:

For example, to program a 2.2ms soft-start time, C7

should be 12nF.

Regulator Enable/Undervoltage-Lockout

Level (EN/UVLO)

The device offers an adjustable-input, undervoltage-

lockout level. For normal operation, a shunt should be

installed across pins 1-2 on JU1. To disable the output,

install a shunt across pins 2-3 on JU1 and pull the EN/

UVLO pin to GND. See Table 1 for JU1 settings.

Set the voltage at which the device turns on with the resistive

voltage-divider R1/R2 connected from VIN_ to SGND.

Connect the center node of the divider to EN/UVLO.

Choose R1 to be 3.32MΩ and then calculate R2 as follows:

INU

R1x1.215

R2

V

1.215

=

−

to turn on.

Mode/SYNC Selection (MODE)

The device’s MODE pin should be used to select among

the PWM, PFM, or DCM modes of operation. The logic

EN/UVLO voltages exceed the respective UVLO rising

thresholds and all internal voltages are ready to allow LX

switching. State changes on the MODE pin are ignored

during normal operation. Refer to the MAX17536 IC data

sheet for more information on the PWM, PFM, and DCM

modes of operation.

Table 2 shows EV kit jumper settings that can be used to

configure the desired mode of operation.

The internal oscillator of the device can be synchronized

to an external clock signal on the SYNC pin. The external

set by R5. The minimum external clock high pulse width

should be greater than 50ns and the minimum external

clock low pulse width should be greater than 160ns.

Table 1. Regulator Enable (EN/UVLO)

Description (JU1)

*Default position.

*Default position.

Table 2. MODE Description (JU2)

SHUNT

POSITION

EN/UVLO PIN

MAX17536_

OUTPUT

1-2*

Connected to VIN

Enabled

Not

installed

Connected to the center

node of resistor-divider

R1 and R2

Enabled, UVLO level

set through the R1

and R2 resistors

2-3

Connected to SGND

Disabled

SHUNT

POSITION

MODE PIN

MAX17536_

MODE

Not installed*

Unconnected

PFM mode of

operation

1-2

Connected to SGND

PWM mode of

operation

2-3

Connected to VCC

DCM mode of

operation