4A, 2MHz Step-Down Regulator

with Integrated Switches

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9

Pin Description

PIN

NAME

FUNCTION

1

MODE

Functional MODE Selection Input. See the MODE Selection section for more information.

3.3V LDO Output. Supply input for the internal analog core. Connect a low-ESR, ceramic capacitor with a

3

CTL1

4

CTL2

Preset Output-Voltage Selection Inputs. CTL1 and CTL2 set the output voltage to one of nine preset

voltages. See Table 1 and the Programming the Output Voltage (CTL1, CTL2) section for preset voltages.

5

REFIN

External Reference Input. Connect REFIN to SS to use the internal 0.6V reference. Connecting REFIN to an

external voltage forces FB to regulate to the voltage applied to REFIN. REFIN is internally pulled to GND

when the IC is in shutdown/hiccup mode.

6SS

Soft-Start Input. Connect a capacitor from SS to GND to set the startup time. Use a capacitor with a 1nF

minimum value. See the Soft-Start and REFIN section for details on setting the soft-start time.

7

GND

Analog Ground Connection. Connect GND and PGND together at one point near the input bypass capacitor

return terminal.

8

COMP

Voltage Error-Amplifier Output. Connect the necessary compensation network from COMP to FB and OUT.

COMP is internally pulled to GND when the IC is in shutdown/hiccup mode.

9FB

Feedback Input. Connect FB to the center tap of an external resistive divider from the output to GND to set

CTL1 and CTL2 to select any of nine preset voltages.

10

OUT

Output-Voltage Sense. Connect to the converter output. Leave OUT unconnected when an external resistive

divider is used.

11

FREQ

Oscillator Frequency Select. Connect a precision resistor from FREQ to GND to select the switching

frequency. See the Frequency Select (FREQ) section.

12

PWRGD

internal UVLO threshold, or the IC is in thermal shutdown.

13

BST

High-Side MOSFET Driver Supply. Internally connected to IN through a PMOS switch. Bypass BST to LX with

a 0.1µF capacitor.

14, 15,

16

LX

Inductor Connection. All LX pins are internally shorted together. Connect all LX pins to the switched side of

the inductor. LX is high impedance when the IC is in shutdown mode.

17–20

PGND

Power Ground. Connect all PGND pins externally to the power ground plane. Connect all PGND pins

together near the IC.

21, 22,

23

IN

Input Power Supply. Input supply range is from 2.9V to 5.5V. Bypass IN to PGND with a 22µF ceramic

capacitor.

24

EN

Enable Input. Logic input to enable/disable the MAX15038.

—EP

Exposed Pad. Solder EP to a large contiguous copper plane connected to PGND to optimize thermal

performance. Do not use EP as a ground connection for the device.