MP2420―75V, 0.3A, SYNCHRONOUS STEP-DOWN CONVERTER WITH WATCHDOG

MP2420 Rev. 1.0

www.MonolithicPower.com

10

9/6/2015

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PIN FUNCTIONS

Pin #

Name

Description

Watchdog

1

WDO

Watchdog output. WDO outputs the reset signal to the MCU.

2

WDI

Watchdog input. WDI receives the trigger signal from the MCU.

3

MODE

Mode switching. Pull MODE high to make the watchdog work in long window

mode; pull MODE low to make the watchdog work in short window mode. MODE

has a weak internal pull-up.

4

GND

Ground. Connect GND as close the output capacitor as possible to avoid high-

current switch paths.

14

VCC

Power input.

15

TIMER

Watchdog timer. Set the time-out with an external resistor.

16

/WD_DIS

Watchdog disable. Pull /WD_DIS low to disable the watchdog; pull /WD_DIS high

to enable the watchdog. /WD_DIS has a weak internal pull-up.

DC/DC

4

GND

Ground. Same as GND in Watchdog.

5

IN

Input supply. IN requires a decoupling capacitor connected to ground to reduce

switching spikes.

6

EN

Enable input. Pull EN below the low threshold to shut the chip down; pull EN

above the high threshold to enable the chip. Float EN to shut the chip down.

7

VREF

Reference voltage output.

8

FB

Feedback input to the error amplifier (for QFN-10 (3mmx3mm) package only).

Connect FB to the tap of an external resistive divider between output and GND. FB

sets the regulation voltage when compared to the internal 1V reference.

9

SS

Soft-start control input. Connect a capacitor from SS to GND to set the soft-start

period.

10

POK

90% of the reference. POK is pulled down during shutdown.

11

BIAS

2.9V. BIAS is the feedback input for the SOIC-8 E package, which has a fixed

output only.

12

BST

Bootstrap. BST is the positive power supply for the internal floating high-side

MOSFET driver. Connect a bypass capacitor between BST and SW.

13

SW

Switch node.

Exposed Pad Connect the exposed pad to the GND plane for optimal thermal performance.