MP5455 – PEAK POWER ASSIST FOR LOW-POWER APPLICATIONS

MP5455 Rev. 1.01

www.MonolithicPower.com

9

2/2/2018

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PIN FUNCTIONS

Pin #

Name

Description

1

DVDT

Slew rate control pin for VB during start-up. Leave DVDT floating for the default

soft-start time (around 0.9ms from 0V to 5V).

2

NC

Factory use only. Leave NC floating.

3

ILIM

Input current limit setting. Do not leave ILIM floating.

4

5

6

EN

On/off control pin for the MP5455. When EN is pulled low, all functions of the

MP5455 are disabled (for both the input current limiter and the charge/release

circuitry). Ensure that the EN voltage is high during release.

7

ENCH

On/off control pin for the charge/release circuitry. When ENCH is pulled down, the

release circuitry is disabled. Note that ENCH must be kept high to achieve energy

release.

8

PGND

Power ground.

9

SW

Switching node for the charge/release circuitry. Connect a small inductor between

SW and VBO.

10

STRG

Storage voltage. Connect the appropriate storage capacitors for the energy storage

and release operation.

11

BST

Bootstrap pin for the charge/release circuitry. The internal bi-directional switcher

requires a bootstrap capacitor (100nF) from BST to SW to supply the high-side switch

driver voltage during release.

12

CST

High-side switch driving voltage storage. The MP5455 supports energy, even when

the storage voltage is close to the VB-regulated voltage.

13

NC

No connection.

14

AGND

IC signal ground.

15

FBB

Bus voltage feedback sense. FBB sets the bus release voltage.

16

FBS

Storage voltage feedback sense. FBS sets the storage voltage.

17

ICH

Boost mode current limit adjustment. Do not pull ICH to VCC or an external voltage

source.

18

VBO

Internal boost. VBO is the input voltage after passing through the input isolation

MOSFET.

19

VB

Internal bus voltage. Place a 22μF to 47μF ceramic capacitor as close to VB as

possible.

20

VIN

Input supply voltage. The MP5455 operates from an unregulated 2.7V to 7V input.

Place a ceramic capacitor 0.1µF or larger as close to VIN as possible. A TVS diode at

the input is necessary if the VIN spike is high. Refer to the Selecting the Input

Capacitor and TVS section on page 12 for additional details.