HCPL-7520-300E 查看數據表（PDF） - Avago Technologies

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HCPL-7520-300E

Isolated Linear Sensing IC

Avago Technologies 

Application Information

Power Supplies and Bypassing

The recommended supply connections are shown in

Figure 16. A floating power supply (which in many ap-

plications could be the same supply that is used to

drive the high-side power transistor) is regulated to 5 V

using a simple zener diode (D1); the value of resistor R4

should be chosen to supply sufficient current from the

existing floating supply. The voltage from the current

sensing resistor (Rsense) is applied to the input of the

HCPL-7520 through an RC anti-aliasing filter (R2 and

C2). Although the application circuit is relatively simple,

a few recom- mendations should be followed to ensure

optimal performance.

The power supply for the HCPL -7520 is most often

obtained from the same supply used to power the

power transistor gate drive circuit. If a dedicated supply

is required, in many cases it is possible to add an ad-

ditional winding on an existing transformer. Otherwise,

some sort of simple isolated supply can be used, such

as a line powered transformer or a high-frequency DC-

DC converter.

An inexpensive 78L05 three-terminal regulator can also

be used to reduce the floating supply voltage to 5 V. To

help attenuate high- frequency power supply noise or

ripple, a resistor or inductor can be used in series with

the input of the regulator to form a low-pass filter with

the regulator’s input bypass capacitor.

HV+

GATE DRIVE

CIRCUIT

MOTOR

+ R1 -

RSENSE

R4

D1

5.1 V

R2

39 Ω

+

FLOATING

POSITIVE

SUPPLY

-

C1

0.1 µF

C2

0.01 µF

1 VDD1

2 VIN+

3 VIN-

4 GND1

HCPL-7520

HV-

Figure 16. Recommended supply and sense resistor connections.

11

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