Step-Down Regulator Output Voltages

(VOUT1, VOUT2)

Regulator output VOUT1 is set to 3.3V with resistors

R22 and R23 and provides up to 4A at 90% efficiency.

Capacitors C15, C16, and C17, and resistors R18 and

R19 provide a compensation network for VOUT1 on the

EV kit.

Regulator output VOUT2 is set to 1.5V with resistors

R18 and R19 and provides up to 2A at 84% efficiency.

Capacitors C5, C6, and C7, and resistors R16 and

R17 provide a compensation network for VOUT2 on

the EV kit.

VOUT1 and VOUT2 output voltages can be reconfig-

ured between 0.6V to VIN by replacing the respective

feedback resistors. To reconfigure the regulator out-

puts, refer to the

Compensation Design Guidelines sec-

tion in the MAX15022 IC data sheet for instructions on

selecting new resistor values. Also refer to the

Effective

Input-Voltage Range section in the MAX15022 IC data

sheet for the minimum and maximum input-voltage

range when reconfiguring the regulator outputs.

Component changes are necessary for proper opera-

tion after reconfiguring the output voltage. Refer to the

Inductor Selection, Input-Capacitor Selection, and the

Compensation Design Guidelines sections in the

MAX15022 IC data sheet to select the proper values.

2.5V LDO Output (VOUT3)

The VOUT3 LDO output is set to 2.5V by feedback

resistors R3 and R4 and provide up to 500mA of output

current. Jumper JU1 selects the input power source for

VOUT3 or configures VOUT3 for power-supply

sequencing with VOUT1. Install a shunt across pins 1-2

to select VIN as the input power source. Install a shunt

across pins 2-3 to select VOUT1 as the LDO input

power source. Resistors R5 and R6 set VOUT3 turn-on

threshold to 3V. See Table 2 for proper jumper configu-

ration of VOUT3 input power source.

To reconfigure VOUT3 to different output voltages, refer

to the

Output 3 and Output 4 Voltage Selection section in

the MAX15022 IC data sheet for additional information.

VOUT3 current capability is restricted by the regulator’s

input power source, the output voltage setting, and

transistor Q1. Verify that Q1 power dissipation rating is

not exceeded when operating the LDO regulator at

high input-to-output voltage differentials and full load.

1.2V Regulator Output (VOUT4)

VOUT4 LDO output is set to 1.2V by feedback resistors

R9 and R10 and provides up to 500mA of output cur-

rent. Jumper JU2 selects the input power source for

VOUT4 or configures VOUT4 for power-supply

sequencing with VOUT2. Install a shunt across pins 1-2

to select VIN as the input power source. Install a shunt

across pins 2-3 to select VOUT2 as the LDO input

power source. Resistors R11 and R12 set the VOUT4

turn-on threshold to 1.3V. See Table 3 for proper

jumper configuration of VOUT4 input power source.

To reconfigure VOUT4 to different output voltages, refer

to the

Output 3 and Output 4 Voltage Selection section in

the MAX15022 IC data sheet for additional information.

VOUT4 current capability is restricted by the regulator’s

input power source, the output voltage setting, and

transistor Q2. Verify that Q2 power dissipation rating is

not exceeded when operating the LDO regulator at

high input-to-output voltage differentials and full load.

Switching Frequency

The MAX15022 switching frequency is set to 2MHz by

resistor R24. Replace resistor R24 with a new resistor

value to program the switching frequency between

500kHz and 4MHz. Use the following equation to select

R24 when reconfiguring the switching frequency:

When reconfiguring the EV kit switching frequency, it is

necessary to replace the compensation network and

power components. Refer to the

Inductor Selection and

Compensation Design Guidelines sections in the

MAX15022 IC data sheet for computing new compen-

sation and power component values.

24

≅×

×

−

(.

)

MAX15022 Evaluation Kit

4

_______________________________________________________________________________________

Table 2. VOUT3 Input Power Source (JU1)

SHUNT

POSITION

VOUT3 INPUT

POWER SOURCE

EV KIT OPERATION

1-2

VIN

VOUT3 enabled

2-3

VOUT1

VOUT3 enabled

Not

installed

—

VOUT3 disabled

Table 3. VOUT4 Input Power Source (JU2)

SHUNT

POSITION

VOUT4 INPUT

POWER SOURCE

EV KIT OPERATION

1-2

VIN

VOUT4 enabled

2-3

VOUT2

VOUT4 enabled

Not

installed

—

VOUT4 disabled