LTC3203 datasheet(9/16 Pages) LINER

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LTC3203/LTC3203-1

LTC3203B/LTC3203B-1

32031fa

When the output voltage drops enough to overcome the

burst comparator hysteresis, the part wakes up and com-

mences normal fixed frequency operation. The output

capacitor recharges and causes the part to re-enter the

Sleep state if the output load still remains less than the

Burst Mode threshold. This Burst Mode threshold varies

with VIN, VOUT and the choice of output storage capacitor.

Short-Circuit/Thermal Protection

The LTC3203/LTC3203-1/LTC3203B/LTC3203B-1 have

built-in short-circuit current limit as well as over-tempera-

ture protection. During a short-circuit condition, the chip

will automatically limit the output current to approximately

1A. At higher temperatures, or if the input voltage is high

enough to cause excessive self-heating of the part, the

thermal shutdown circuitry will shut down the charge

pump once the junction temperature exceeds approxi-

mately 150

°C. It will enable the charge pump once the

junction temperature drops back to approximately 135

°C.

The LTC3203/LTC3203-1/LTC3203B/LTC3203B-1 will

cycle in and out of thermal shutdown indefinitely without

latch-up or damage until the short circuit condition on

VOUT is removed.

Soft-Start

To prevent excessive current flow at VIN during start-up,

the LTC3203/LTC3203-1/LTC3203B/LTC3203B-1 have

built-in soft-start circuitry. Soft-start is achieved by in-

creasing the amount of current available to the output

charge storage capacitor linearly over a period of approxi-

mately 250

µs.

OPERATIO

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