TPS65276VRHHT datasheet(23/43 Pages) TI

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TPS65276V

www.ti.com

SLVSBW0B – FEBRUARY 2013 – REVISED JANUARY 2014

High-Side MOSFET Over Current Protection

The device implements current mode control which uses the COMP pin voltage to control the turn off of the high-

side MOSFET and the turn on of the low-side MOSFET on a cycle by cycle basis. Each cycle the switch current

and the current reference generated by the COMP pin voltage are compared, when the peak switch current

intersects the current reference the high-side switch is turned off.

Low-Side MOSFET Over Current Protection

While the low-side MOSFET is turned on its conduction current is monitored by the internal circuitry. During

normal operation the low-side MOSFET sources current to the load. At the end of every clock cycle, the low-side

MOSFET sourcing current is compared to the internally set low-side sourcing current limit. If the low-side

sourcing current is exceeded, the high-side MOSFET is not turned on and the low-side MOSFET stays on for the

next cycle. The high-side MOSFET is turned on again when the low-side current is below the low-side sourcing

current limit at the start of a cycle.

The low-side MOSFET may also sink current from the load. If the low-side sinking current limit is exceeded the

low-side MOSFET is turned off immediately for the rest of that clock cycle. In this scenario both MOSFETs are

off until the start of the next cycle.

Furthermore, if an output overload condition (as measured by the COMP pin voltage) has lasted for more than

the hiccup wait time which is programmed for 512 switching cycles, the device will shut down itself and restart

after the hiccup time of 16384 cycles. The hiccup mode helps to reduce the device power dissipation under

severe overcurrent conditions.

Thermal Shutdown

The internal thermal shutdown circuitry forces the device to stop switching if the junction temperature exceeds

160°C typically. Once the junction temperature drops below 140°C typically, the internal thermal hiccup timer will

start to count. The device reinitiates the power up sequence after the built-in thermal shutdown hiccup time

(16384 cycles) is over.

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TPS65276VRHHT Datasheet(PDF) 23 Page - Texas Instruments