AN2785 datasheet(13/51 Pages) STMICROELECTRONICS

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AN2785

Application examples

Doc ID 14785 Rev 1

13/51

Application examples

6.1

Basic topology: single half-bridge

A typical schematic for one half-bridge is shown in Figure 8.

Figure 8.

Typical schematic of power half-bridge

The half-bridge comprises two power switches such as IGBTs (or MOSFETs), one high-side

and one low-side. When the high-side switch is ON, it brings the output voltage of the half-

bridge to the HV bus voltage, which can be a high DC voltage power supply with large power

availability, while the low-side switch shorts the output to the power ground voltage when it is

ON. Thanks to the internal floating structure for the high-side switch driving, n-type IGBTs

(or n-channel MOSFETs) can be used. The gate driver works exactly like a digital/analog-

power interface between the controller and the power stage. Note that it is usually

recommended (not mandatory) to have some gate resistances between each power switch

gate and the corresponding gate driver output, in order to limit current during the gate

charge.

6.1.1

VCC supply pin

Regarding the VCC pin, a local filtering of the supply voltage very close to the L6393 IC is

recommended. Generally, the suggestion is to use two capacitors, one electrolytic with a

greater value (CVCC1 = 10 µF, for example), which has a great energy capability but also a

non-negligible ESR (so is quite slow in providing the current) and a second smaller ceramic

capacitor (CVCC2 = 100 nF) which has a lower ESR value but a lower energy capability. The

first capacitor works mainly as the bulk energy storage while the second is able to supply the

dynamic current spikes required by the commutations of the device, so is better for high-

frequency decoupling of the IC supply voltage.

PHASE

BRAKE

HVG

H.V.

TO LOAD

OUT

LVG

VBOOT

CP+

CP-

GND

CPOUT

FROM CONTROLLER

VCC

33 Ω 0.25W

0 Ω 0.25W

1N4148

33 Ω 0.25W

0 Ω 0.25W

1N4148

100 nF

25V

10 uF

25V

15V

100 nF

25V

STGP10NC60HD

100 nF

25V

47 kΩ

0.25W

L6393

100 uF

400V

RGH_ON

RGH_OFF

RGL_ON

RGL_OFF

CHV

CBOOT

CVCC1

CVCC2

RDT

CDT

FROM CONTROLLER

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