ACPL-P314-060E 데이터 시트보기 (PDF) - Avago Technologies

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ACPL-P314-060E

0.6 Amp Output Current IGBT Gate Driver Optocoupler

Avago Technologies 

Applications Information

Eliminating Negative IGBT Gate Drive

To keep the IGBT firmly off, the ACPL-P314/W314 has a

very low maximum VOL specification of 1.0 V. Minimizing

Rg and the lead inductance from the ACPL-P314/W314

to the IGBT gate and emitter (possibly by mounting the

ACPL-P314/W314 on a small PC board directly above the

IGBT) can eliminate the need for negative IGBT gate drive

in many applications as shown in Figure 19. Care should

be taken with such a PC board design to avoid routing

the IGBT collector or emitter traces close to the ACPL-

P314/W314 input as this can result in unwanted coupling

of transient signals into the input of ACPL-P314/W314

and degrade performance. (If the IGBT drain must be

routed near the ACPL-P314/W314 input, then the LED

should be reverse biased when in the off state, to prevent

the transient signals coupled from the IGBT drain from

turning on the ACPL-P314/W314.

Selecting the Gate Resistor (Rg)

Step 1: Calculate Rg minimum from the IOL peak specifi-

cation. The IGBT and Rg in Figure 19 can be analyzed as

a simple RC circuit with a voltage supplied by the ACPL-

P314/W314.

R g ³ VCC − V OL

IOLPEAK

24 − 5

=

0.6

= 32 Ω

The VOL value of 5 V in the previous equation is the VOL at

the peak current of 0.6A. (See Figure 6).

Step 2: Check the ACPL-P314/W314 power dissipation

and increase Rg if necessary. The ACPL-P314/W314 total

power dissipation (PT) is equal to the sum of the emitter

power (PE) and the output power (PO).

PT =PE +PO

PE = IF u V F u DutyCycle

P O = P O(BIAS) + P O(SWITCHING) = ICC u V CC + E SW (Rg; Q g ) u f

= (I CCBIAS + K ICC u Q g u f) u VCC + E SW (Rg ; Q g ) u f

where KICC · Qg · f is the increase in ICC due to switching

and KICC is a constant of 0.001 mA/(nC*kHz). For the

circuit in Figure 19 with IF (worst case) = 10 mA, Rg = 32

, Max Duty Cycle = 80%, Qg = 100 nC, f = 20 kHz and

TAMAX = 85°C:

PE = 10 mA u 1.8V u 0.8 = 14 mW

PO = (3 mA + (0.001 mA/nC u kHz) u 20 kHz u 100 nC) u 24V +

0.4 μJ u 20 kHz = 128 mW £ 250 mW ( P O(MAX) @85 °C)

The value of 3 mA for ICC in the previous equation is the

max. ICC over entire operating temperature range.

Since PO for this case is less than PO(MAX), Rg = 32  is

alright for the power dissipation.

4.0

Qg = 50 nC

3.5

Qg = 100 nC

3.0

Qg = 200 nC

Qg = 400 nC

2.5

2.0

1.5

1.0

0.5

0

0

20

40 60 80 100

Rg – GATE RESISTANCE – Ω

Figure 20. Energy Dissipated in the ACPL-P314/W314 and for Each IGBT

Switching Cycle.

+5 V

CONTROL

INPUT

74XXX

OPEN

COLLECTOR

270 Ω

1

2

3

ACPL-P314/W314

6

0.1 μF

5

4

+ VCC = 24V

-

Rg Q1

Q2

Figure 19. Recommended LED Drive and Application Circuit for ACPL-P314/W314

+ HVD

3-PHASE

AC

- HVDC

11

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