ACPL-W456-060E データシートの表示（PDF） - Broadcom Corporation

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ACPL-W456-060E

High CMR Intelligent Power Module and Gate Drive Interface Optocoupler

Broadcom Corporation 

ACPL-P456 and ACPL-W456

Data Sheet

Figure 20 Recommended LED Drive Circuit for Ultra High CMR

+5V

1

6

2

5

3

SHIELD

4

IPM Dead Time and Propagation Delay

Specifications

The ACPL-P456/W456 includes a Propagation Delay Difference

specification intended to help designers minimize “dead time”

in their power inverter designs. Dead time is the time period

during which both the high and low side power transistors (Q1

and Q2 in Figure 21) are off. Any overlap in Q1 and Q2

conduction will result in large currents flowing through the

power devices between the high and low voltage motor rails.

To minimize dead time the designer must consider the

propagation delay characteristics of the optocoupler as well as

the characteristics of the IPM IGBT gate drive circuit.

Considering only the delay characteristics of the optocoupler

(the characteristics of the IPM IGBT gate drive circuit can be

analyzed in the same way) it is important to know the

minimum and maximum turn on (tPHL) and turn-off (tPLH)

propagation delay specifications, preferably over the desired

operating temperature range.

Figure 21 Typical Application Circuit

ILED1

+5V

1

2

310

3

CMOS

ILED2

+5V

1

2

310

3

CMOS

SHIELD

SHIELD

6

VCC1

VOUT1

5

4

6

VCC2

20

VOUT2

5

4

ACPL-P/W456

ACPL-P/W456

ACPL-P/W456

ACPL-P/W456

ACPL-P/W456

The limiting case of zero dead time occurs when the input to

Q1 turns off at the same time that the input to Q2 turns on. This

case determines the minimum delay between LED1 turn-off

and LED2 turn-on, which is related to the worst case

optocoupler propagation delay waveforms, as shown in

Figure 22. A minimum dead time of zero is achieved in

Figure 22 when the signal to turn on LED2 is delayed by (tPLH

max – tPHL min) from the LED1 turn off. Note that the

propagation delays used to calculate PDD are taken at equal

temperatures since the optocouplers under consideration are

typically mounted in close proximity to each other.

(Specifically, previous equation are not the same as the tPLH

max and tPHL min, over the full operating temperature range,

specified in the data sheet.) This delay is the maximum value

for the propagation delay difference specification which is

specified at 450 ns for the ACPL-P456/W456 over an operating

temperature range of –40°C to +100°C.

Delaying the LED signal by the maximum propagation delay

difference ensures that the minimum dead time is zero, but it

does not tell a designer what the maximum dead time will be.

The maximum dead time occurs in the highly unlikely case

where one optocoupler with the fastest tPLH and another with

the slowest tPHL are in the same inverter leg. The maximum

dead time in this case becomes the sum of the spread in the

tPLH and tPHL propagation delays as shown in Figure 23. The

maximum dead time is also equivalent to the difference

between the maximum and minimum propagation delay

difference specifications. The maximum dead time (due to the

optocouplers) for the ACPL-P456/W456 are 600 ns (= 450 ns –

(–150 ns)) over an operating temperature range of –40°C to

+100°C.

IPM

+HV

M

-HV

Broadcom

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