MAXM17536EVKIT datasheet(2/11 Pages) MAXIM

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Evaluates: MAXM17536 5V Output

MAXM17536 5V Output

Evaluation Kit

Detailed Description of Hardware

The MAXM17536EVKIT# is a proven circuit to demonstrate

the high-voltage, high-efficiency, and compact solution

size of the MAXM17536 synchronous step-down DC-DC

power module. The output voltage is preset to 5V to

operate from 7V to 60V input and provides up to 4A load

current. The optimal frequency is set at 450kHz to

maximize efficiency and minimize component size. The

EV kit includes test points, for monitoring the RESET, LX

voltage, DL voltage, BST, and VCC voltage.

Soft-Start Input (SS)

The MAXM17536 module implements adjustable soft-start

operation to reduce inrush current. A capacitor connected

from the SS pin to SGND programs the soft-start time.

The selected output capacitance (CSEL) and the output

voltage (VOUT) determine the minimum required soft-start

capacitor as follows:

CSS ≥ 28 x 10-6 x CSEL x VOUT

The soft-start time (tSS) is related to the capacitor

connected at SS (CSS) by the following equation:

tSS = CSS/(5.55)

where tSS is in ms and CSS is in nF. For example, to

program a 4ms soft-start time, a 22nF capacitor should be

connected from the SS pin to SGND.

Regulator Enable/Undervoltage-Lockout Level

(EN/UVLO)

The EV kit offers an adjustable input undervoltage-lockout

level by resistor-dividers connecting between the IN, EN/

UVLO, and GND pins. For normal operation, a shunt

should not be installed across pins 1-2 on J1 to enable

the output through an internal pullup 3.32MΩ resistor from

the EN/UVLO pin to the IN pin. To disable the output, install

the shunt across pins 1-2 on J1 to pull the EN/UVLO pin

to GND. See Table 1 for J1 setting details. The EV kit also

provides an R3 resistor to program a UVLO threshold

voltage at which an input-voltage level device turns on.

The R3 resistor can be calculated by the following equation:

R3 = 3320 x 1.215/(VINU - 1.215)

where VINU is the input voltage at which the device is

required to turn on, and R3 is in kΩ.

MODE/SYNC Selection (MODE)

The device’s MODE pin can be used to select among the

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

of the MODE pin is latched when the VCC and 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 MAXM17536 module data

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

modes of operation.

Table 2 lists J2 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 synchronization clock

frequency must be between 1.1 x fSW and 1.4 x fSW,

where fSW is the frequency of operation set by R4. The

minimum external clock high pulse width should be greater

than 50ns, while the minimum external clock low pulse

width should be greater than 160ns.

Table 1. EN/UVLO Enable/Disable Configuration (J1)

Table 2. MODE Description (J2)

*Default position

SHUNT POSITION

EN PIN

MAXM17536_OUTPUT

1-2

Connected to GND

Disabled

Not installed*

Connected to the center node of

resistor-divider 3.32MΩ and R3

Enabled, UVLO level set through

the 3.32MΩ and R3 resistors

SHUNT POSITION

MODE PIN

MAXM17536_MODE

Not installed

Unconnected

PFM mode of operation

1-2

Connected to VCC

DCM mode of operation

2-3*

Connected to GND

PWM mode of operation

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