6

Functional description

6.1

Logic inputs

The PWD5F60 full bridge features two identical half-bridge sections. Each section has three logic inputs to control

the internal high-side and low-side MOSFETs.

Inputs

Outputs

SD

IN

PWM

HS

LS

0

X

X

OFF

OFF

1

0

0

OFF

ON

1

0

1

OFF

ON

1

1

0

OFF

ON

1

1

1

ON

OFF

The logic inputs have internal pull-down resistors. The purpose of these resistors is to set a defined logic level if,

for example, there is an interruption on the logic lines or the controller outputs are in tri-state conditions.

6.2

Bootstrap structure

Bootstrap circuitry is typically used to supply the high-voltage section. This function is normally accomplished with

a high-voltage fast recovery diode, as shown in Figure 16. (side a).

In the PWD5F60, a patented integrated structure replaces the external diode. The structure consists of a series of

low-voltage diodes and a high-voltage DMOS, driven synchronously by the low-side driver (LVG), as shown in

Figure 16. (side b). An internal bootstrap provides the DMOS driving voltage. The integrated diode structure is

actively turned on and guarantees best performance only when the low-side driver is on.

In applications where the control strategy requires recharging the bootstrap capacitor even when the low-side

driver is off, the use of an external bootstrap diode in parallel to the integrated structure is possible.

b

a

VCC

HVG

LVG

BOOT

VS

VCC

OUT

TO LOAD

HVG

LVG

BOOT

VS

OUT

TO LOAD

PWD5F60

Functional description

DS12543 - Rev 1

page 14/26