MP3429

– 21A, HIGH-EFFICIENCY, FULLY INTEGRATED, SYNC, BOOST CONVERTER

MP3429 Rev. 1.0

www.MonolithicPower.com

13

6/8/2017

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© 2017 MPS. All Rights Reserved.

PIN FUNCTIONS

Pin #

Name

Description

1

SW

Converter switch. SW is connected to the drain of the internal low-side power MOSFET and

the source of the internal high-side synchronous power MOSFET. Connect the power inductor

to SW.

2

VDD

Internal bias supply. Decouple VDD

with a 4.7μF ceramic capacitor placed as close to VDD

as possible. When VIN is higher than 3.4V, VDD is powered by VIN. Otherwise, VDD is

powered by the higher voltage of either VIN or VOUT. If the bias voltage connected to VDD is

higher than 3.4V, the regulator from VIN and VOUT is disabled. The VDD regulator starts

working when VIN is higher than about 0.9V if EN is high. Supply VIN with a power source

higher than 2.7V during VIN start-up to provide enough VDD power voltage.

3

SS

Soft-start programming. Place a capacitor from SS to AGND to set the VOUT rising slew

rate.

4

COMP

Internal error amplifier output. Connect a capacitor and resistor in series from COMP to

AGND for loop compensation.

5

FB

Feedback input. Connect a resistor divider from VOUT to FB.

6

AGND

Analog ground.

7

PGND

Power ground.

8

VOUT

Output. VOUT is connected to the drain of the high-side MOSFET. VOUT powers VDD when

VOUT is higher than VIN and VIN is lower than 3.4V.

9

FTY

Factory use only. FTY must be connected to GND in the application.

10

MODE

MODE selection. If MODE is floating, the MP3429 works in ultrasonic mode (USM). If MODE

is high, the MP3429 works in forced continuous conduction mode (FCCM). If MODE is low, the

MP3429 works in pulse-skip mode (PSM). MODE must always be higher than 0.2V in the

application, even if in PSM. Place a

130kΩ + 20kΩ resistor divider from VDD to MODE to set

the MP3429 in PSM.

11

EN

Chip enable control. When not in use, connect EN to VIN for automatic start-up. EN can

program the VIN UVLO. Do not leave EN floating.

12

VIN

Input supply. VIN must be bypassed locally. Supply VIN with a power source higher than 2.7V

during VIN start-up to provide enough VDD power voltage.

13

BST

Bootstrap. A capacitor between BST and SW powers the synchronous HS-FET.