MP6302 – ENERGY STORAGE AND RELEASE CONTROL IC

MP6302 Rev. 1.02

www.MonolithicPower.com

7

7/17/2015

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OPERATION

The MP6302 is an energy 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. The

MP6302

continuously

monitors

the

input

voltage. Once the input voltage is lower than a

selected release voltage as

in the case of

losing input power, it releases the charge from

the storage capacitors to input side, and keeps

the input voltage regulated to the release

voltage for as long as possible. This allows the

system to respond to input power failure.

Start-up

During power start-up, there are two periods to

charge the storage voltage. In the first period,

the MP6302 pre-charges the large storage

capacitors from 0 to VIN with built-in inrush

current limit. Once the storage voltage is close

to the input voltage, an internal boost circuitry

will continuously charge and regulate the

storage capacitors to the target voltage. The

BST pin of MP6302 should connect to the

DCDC switch node. Figure1 shows the

charging process of MP6302.

VIN

EN of DC/DC

Output of DCDC

Storage Voltage

VIN

Pre-Charge w/ current limit

Target storage voltage

Figure 1—Timing of Charging

Storage Power Good Indicator

When the voltage on FB1 pin is lower than

can be driven to the high logic.

Storage Voltage

After the start up period of MP6302, the storage

voltage can automatically regulated at a

selected output voltage. With the hysteretic

mechanism, when the storage voltage is lower

than selected voltage, an internal controlled

switch is turned on and charges the storage

capacitor. Once the storage voltage is charged

up, the switch turns off and waits for the next

refresh cycle.

Release

The MP6302 keeps monitoring the input voltage.

Once the input voltage is lower than the

selected release voltage as in the case of losing

input power, the MP6302 moves the charge

from high voltage storage capacitor to low input

voltage capacitor through an internal controlled

release path. MP6302 must charge Vs up till

PGs rises to high before a release can be

executed.

The

release

voltage

can

be

determined by choosing appropriate input

resistance divider. The maximum release

current can be as high as 2.5A. The release

process is shown in Figure2.

Vrelease

Vstorage

VIN

GASP

t

Input UVLO of DC/DC converter

Figure 2—Timing of Releasing