Evaluates: MAX15022
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:
where f
SW
is in hertz and R24 is in ohms.
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.
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