Datasheet

TPS40195

SLUS720E –FEBRUARY 2007–REVISED JULY 2012

www.ti.com

Drivers

The drivers for the external HDRV and LDRV MOSFETs are capable of driving a gate-to-source voltage of 5 V.

The LDRV driver switches between VDD and GND, while HDRV driver is referenced to SW and switches

between BOOT and SW. The drivers have non-overlapping timing that is governed by an adaptive delay circuit to

minimize body diode conduction in the synchronous rectifier. The drivers are capable of driving MOSFETS that

are appropriate for a 15-A converter if power dissipation requirements are met. See Package Dissipation Ratings

Table.

Power Good

The TPS40195 provides an indication that output power is good for the converter. This is an open drain signal

and pulls low when any condition exists that would indicate that the output of the supply might be out of

regulation. These conditions include:

• V

> ±10% from nominal

• soft-start is active

• a undervoltage condition exists for the device

• a short circuit condition has been detected

• die temperature is over (150°C)

NOTE

When there is no power to the device, PGOOD is not able to pull close to GND if an

auxiliary supply is used for the power good indication. In this case, a built in resistor

connected from drain to gate on the PGOOD pull down device makes the PGOOD pin

look approximately like a diode to GND.

Thermal Shutdown

Thermal shutdown If the junction temperature of the device reaches the thermal shutdown limit of 150°C, the

PWM and the oscillator is turned off and HDRV and LDRV are driven low, turning off both FETs. When the

junction cools to the required level (130°C nominal), the PWM initiates soft start as during a normal power up

cycle.