Datasheet TLE6280GP

5

2007-07-19

The Input Low-side pins ILx (see Fig. 3) trigger the charge pump. As soon as the first exter-

nal low-side Mosfet is switched on and the corresponding bootstrap capacitor is connected

rectly feed the low-side output stages and recharge the bootstrap capacitors connected to

GND.

down to be re-charged.

This synchronous operation with the output stages has the benefit that the electromagnetic

emissions generated by the charge pump can be filtered by the same filter necessary to filter

the EME of the converter itself. At the same time it is assured that the high voltage at the CH

pin is available just in time to charge the high-side bootstrap.

Fig. 3: Trigger timing of charge pump caused by changing input signals

Vreg1 13V

+13 ... +8V

CH

CL

BH

1

BH

2

BH

3

BL

1

BL

2

BL

3

Vreg2=6V

Vreg3 =

Vreg1-8V

Triggered

by ILx

VS

C

CP

C

BH1

C

BL1

Phase A

Phase B

Phase C

= Pin

Bold line = external component

C

VS

from battery

R

VS

Fig. 2: Supply structure with external components (compare to Fig. 1)

IL1

IL2

Timing of charge pump - Examples

1

2

1. ILx high

1. ILx low

IL3

CH

Charge of bootstrap

capacitors

Charge of charge pump

capacitor

IL2

1. ILx high

1. ILx low

CH

Charge of bootstrap capacitors

IL1

IL3

Charge of charge pump capacitor