Input Source

The MAX15003 EV kit is configured for normal operation

with an input power source of 6V to 14V. However, the

upper input-voltage limit can be raised to 23V by replac-

ing capacitors C1, C2, C8, and C14 with higher voltage-

rated capacitors. The EV kit circuit requires a minimum

5.5V input to generate the 5V regulation voltage (REG)

used to power the MOSFET gate drivers and provide

the pullup voltage for the SEL and PHASE inputs.

Triple Outputs

The MAX15003 EV kit’s three outputs are configured to

different voltages. VOUT1 is configured to 3.3V, with

resistors R16 and R17, and can supply up to 3A.

VOUT2 is configured to 2.5V, with resistors R4 and R5,

and can supply up to 4A. VOUT3 is configured to 1.2V,

with resistors R28 and R29, and can supply up to 10A.

The output voltage for each output can be reconfigured

between 0.6V and 0.9V x IN by replacing the respective

feedback resistors. Refer to the

Type III: Compensation

data sheet for instructions on selecting new resistor val-

ues for the respective outputs. Also refer to the

Inductor

Selection, Input Capacitor Selection, and the

Compensation Design Guidelines sections in the IC

data sheet to verify whether other components need

replacement for proper operation after reconfiguring

the output voltage.

Current Limit

The current limit for each MAX15003 EV kit output is set

with resistors. VOUT1 current limit is set to a nominal

4.5A, at room temperature, with resistors R44 and R23.

VOUT2 current limit is set to a nominal 6A, at room tem-

perature, with resistors R42 and R11. VOUT3 current

limit is set to a nominal 15A, at room temperature, with

resistors R43 and R35. To reconfigure the current limits,

refer to the

Setting the Current Limit section in the

MAX15003 IC data sheet to calculate new resistor val-

ues for R44/R23, R42/R11, and R43/R35.

The MAX15003 IC limits the inductor current by sensing

the voltage drop across the respective MOSFET’s

equivalent low-side sense resistance for each output

can be changed by cutting open the PCB shorting trace

across R9, R21, and R33 and installing sense resistors.

eliminated from the equivalent low-side sense resis-

tance, at each buck converter, by cutting open the PCB

shorting trace across R19, R7, or R31, and installing a

shorting resistor at R20, R31, or R32, respectively. See

Table 1 for current-limit resistor configuration.

Switching Frequency

The MAX15003 PWM switching frequency is set to

600kHz with resistor R40 (165k

Ω). Replace resistor R40

with a new resistor value to progam the switching

frequency between 200kHz and 2.2MHz. Use the fol-

lowing equation to choose the appropriate resistor

The switching frequency can also be synchronized to

an external digital clock signal connected to the EV kit

SYNC PCB pad. For proper synchronization, the exter-

nal signal frequency must be at least 20% higher than

3x the frequency programmed through resistor R40.

The digital clock signal should have peak amplitude of

3V to 5V, offset voltage of 1/2 the amplitude, frequency

in the 600kHz to 6.9MHz range, and a duty cycle of

50%. The MAX15003 IC switching frequency will be 1/3

the SYNC frequency. Refer to the

Inductor Selection,

Input Capacitor Selection, and the Compensation

Design Guidelines sections in the MAX15003 IC data

sheet to verify whether other components need

replacement for proper operation after reconfiguring

the switching frequency.

MAX15003 Evaluation Kit

4

_______________________________________________________________________________________

Table 1. Current-Limit Resistor Configuration

VOUT_ OUTPUT

ILIM_ RESISTORS

OPEN RESISTOR

0

Ω RESISTOR

INDUCTOR CURRENT-SENSING ELEMENTS

R20

R19

N4-A + R21

VOUT1

R44, R23

R19

R20

R21

R8

R7

N1-B + R9

VOUT2

R42, R11

R7

R8

R9

R32

R31

N3 + R33

VOUT3

R43, R35

R31

R32

R33