Datasheet

1.5 MW

200 W

200 kW

1 kW

300 kW

Enable

Chip

VDD

GND

UDG-07005

TPS40195

SLUS720E –FEBRUARY 2007–REVISED JULY 2012

www.ti.com

APPLICATION INFORMATION

Introduction

The TPS40195 is a flexible controller providing all the necessary features to construct a high performance DC-

DC converter while keeping costs to a minimum. Support for pre-biased outputs eliminates concerns about

damaging sensitive loads during startup. Strong gate drivers for the high side and rectifier N channel FETs

decrease switching losses for increased efficiency. Adaptive gate drive timing minimizes body diode conduction

in the rectifier FET, also increasing efficiency. Selectable short circuit protection thresholds and hiccup recovery

from a short circuit increase design flexibility and minimize power dissipation in the event of a prolonged output

fault. A dedicated enable pin (EN) allows the converter to be placed in a low quiescent current shutdown mode.

Enable Functionality

The TPS40195 has a dedicated device enable (EN) pin. This simplifies user level interface design since no

multiplexed functions exist. Another benefit is a true low power shutdown mode of operation. When the EN pin is

pulled to GND, all unnecessary functions inside the IC, including the BP regulator, are turned off and the

TPS40195 consumes a typical 165-μA of current. A functionally equivalent circuit to the enable circuitry on the

TPS40195 is shown in Figure 16.

Figure 16. TPS40195 EN Pin Internal Circuitry

If the EN pin is left floating, the chip starts automatically. The pin must be pulled to less than 600 mV for the

TPS40195 to be in shutdown mode. Note that the EN pin is relatively high impedance. In some situations, there

could be enough noise nearby to cause the EN pin to swing below the 600 mV threshold and give erroneous

shutdown commands to the rest of the device. There are two solutions to this problem should it arise.

1. Place a capacitor from EN to GND. A side effect of this is to delay the start of the converter while the

capacitor charges past the enable threshold

2. Place a resistor from VDD to EN. This causes more current to flow in the shutdown mode, but does not delay

converter startup. If a resistor is used, the total current into the EN pin should be limited to no more than 500

μA.