HCPL-0466-560E View Datasheet(PDF) - Avago Technologies

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HCPL-0466-560E

Intelligent Power Module and Gate Drive Interface Optocouplers

Avago Technologies 

IPM Dead Time and Propagation Delay Specifications

The HCPL-4506 series include a Propa­gation Delay Differ-

ence 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  24) are off. Any

overlap in Q1 and Q2 conduc­tion will result in large cur-

rents 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 impor-

tant to know the mini­mum and maximum turn-on (tPHL)

and turn-off (tPLH) propagation delay specifications, pref-

erably over the desired operating temperature range.

The limiting case of zero dead time occurs when the in-

put to Q1 turns off at the same time that the input to

Q2 turns on. This case determines the minimum de-

lay between LED1 turn-off and LED2 turn-on, which

is related to the worst case optocoupler propaga­tion

delay waveforms, as shown in Figure 25. A minimum

dead time of zero is achieved in Figure 25 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 tem-

peratures since the opto­couplers under consideration

are typically mounted in close proximity to each other.

(Specifically, tPLH max and tPHL min in the previous equa-

tion 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 propaga­

tion delay differ­ence specification which is specified at

450 ns for the HCPL-4506 series over an operating tem-

perature 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 maxi-

mum dead time will be. The maximum dead time oc-

curs 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 26.

The maximum dead time is also equivalent to the differ-

ence between the maximum and mini­mum propagation

delay difference specifications. The maximum dead time

(due to the optocoup­lers) for the HCPL-4506 series is

600 ns (= 450 ns - (-150 ns) ) over an operating tempera-

ture range of ‑40°C to 100°C.

For product information and a complete list of distributors, please go to our website: www.avagotech.com

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Data subject to change. Copyright © 2005-2008 Avago Technologies Limited. All rights reserved. Obsoletes AV01-0551EN

AV02-1360EN - June 20, 2008

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