MP201 – DYING GASP STORAGE AND RELEASE CONTROL IC

MP201 Rev. 1.01

www.MonolithicPower.com

8

11/27/2012

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© 2012 MPS. All Rights Reserved.

OPERATION

MP201 is a dying gasp storage and release

control IC. It charges the storage capacitors

from input supply during power start up and

keeps refreshing the storage voltage at a

regulated value during normal operation.

MP201 continuously monitors the input voltage.

Once the input voltage is lower than the

programmed release voltage in the case of

losing input power, it releases the charge from

the storage capacitors to input, and keeps the

input voltage regulated to the release voltage

for as long as possible. It allows the system to

respond to input power failure.

Start-Up

During the power start-up, there are two periods

to charge the storage capacitors. In the first

period, the MP201 pre-charges the large

storage capacitors from 0 to nearly VIN with

built-in inrush current limit. Once the storage

voltage is close to the input voltage, the storage

voltage is boosted and regulated at target

voltage.

The BST pin of MP201 should connect to the

DCDC switch node. Only after the DCDC is

enabled, the MP201 will start boosting. Figure 2

shows the charging build-up process of MP201.

VIN

EN of DC/DC

Output of DCDC

Storage Voltage

VIN

Pre-Charge w/ current limit

Target storage voltage

Figure 2 – Timing of Charging

Release

MP201 keeps monitoring the input voltage.

Once the input voltage is lower than selected

release voltage in the case of losing input

power, MP201 moves the charge from high

voltage storage capacitor to low input voltage

capacitor.

The

release

voltage

can

be

determined by choosing appropriate input

resistance divider. The maximum LDO release

current can be as high as 2.5A. Until the

storage capacitor voltage is near the input

voltage, the input voltage loses its regulation

and reduces further. A conceptual release

process of MP201 is shown in Figure 3.

Vrelease

Vstorage

VIN

GASP

t

Input UVLO of DC/DC converter

Figure 3 – Timing of Releasing

Gasp Indicator

When the FB2 voltage, feedback voltage for the

GASP pin will be pulled high. Connect a resistor

across VIN and GASP can drive GASP high.

the GASP voltage will be internally pulled low.

GASP voltage can be used as a communication

indicator signal which states input power

availability.