Datasheet

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SLVS196C − JANUARY1999 − REVISED JANUARY 2001
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Terminal Functions
TERMINAL
I/O
DESCRIPTION
NAME NO.
I/O
DESCRIPTION
BOOT 14 I Bootstrap terminal. A ceramic capacitor is connected between BOOT and BOOTLO terminals to develop the
floating bootstrap voltage for the high-side MOSFET. The capacitor value is typically between 0.1 µF and 1 µF.
A 1-MΩ resistor should be connected across the bootstrap capacitor to provide a discharge path when the driver
has been powered down.
BOOTLO 11 O This terminal connects to the junction of the high-side and low-side MOSFETs.
CROWBAR 3 I CROWBAR can to be driven by an external OVP circuit to protect against a short across the high-side MOSFET.
If CROWBAR is driven low, the low-side driver will be turned on and the high-side driver will be turned off,
independent of the status of all other control terminals.
DT 6 I Dead-time control terminal. Connect DT to the junction of the high-side and low-side MOSFETs.
ENABLE 1 I If ENABLE is low, both drivers are off.
HIGHDR 12 O Output drive for the high-side power MOSFET
IN 2 I Input signal to the MOSFET drivers (noninverting input for the TPS2830; inverting input for the TPS2831).
LOWDR 10 O Output drive for the low-side power MOSFET
NC 4, 9, 13 No internal connection
PGND 7 Power ground. Connect to the FET power ground
SYNC 5 I Synchronous Rectifier Enable terminal. If SYNC is low, the low-side driver is always off; If SYNC is high, the
low-side driver provides gate drive to the low-side MOSFET.
V
CC
8 I Input supply. Recommended that a 1-µF capacitor be connected from V
CC
to PGND.
detailed description
low-side driver
The low-side driver is designed to drive low Rds(on) N-channel MOSFETs. The current rating of the driver is
2 A, source and sink.
high-side driver
The high-side driver is designed to drive low Rds(on) N-channel MOSFETs. The current rating of the driver is
2 A, source and sink. The high-side driver can be configured as a GND-reference driver or as a floating bootstrap
driver. The internal bootstrap diode is a Schottky, for improved drive efficiency. The maximum voltage that can
be applied from BOOT to ground is 30 V.
dead-time (DT) control
†
Dead-time control prevents shoot through current from flowing through the main power FETs during switching
transitions by controlling the turn-on times of the MOSFET drivers. The high-side driver is not allowed to turn
on until the gate drive voltage to the low-side FET is low, and the low-side driver is not allowed to turn on until
the voltage at the junction of the power FETs (Vdrain) is low; the DT terminal connects to the junction of the power
FETs.
ENABLE
†
The ENABLE terminal enables the drivers. When enable is low, the output drivers are low.
IN
†
The IN terminal is the input control signal for the drivers. The TPS2830 has a noninverting input; the TPS2831
has an inverting input.
†
High-level input voltages on ENABLE, SYNC, CROWBAR, IN, and DT must be greater than or equal to 0.7V
CC
.