ACPL-P314-000E Просмотр технического описания (PDF) - Avago Technologies

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производитель

ACPL-P314-000E

0.6 Amp Output Current IGBT Gate Driver Optocoupler

Avago Technologies 

+5 V

1

CLEDP

6

2

5

3

CLEDN

SHIELD

4

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 is equivalent

to the difference between the maximum and minimum

propagation delay difference specification as shown in

Figure 27. The maximum dead time for the ACPL-P314/

W314 is 1 μs (= 0.5 μs - (-0.5 μs)) over the operating tem-

perature range of –40°C to 100°C.

Figure 25. Recommended LED Drive Circuit for Ultra-High CMR Dead Time

ILED1

and Propagation Delay Specifications.

Dead Time and Propagation Delay Specifications

The ACPL-P314/W314 includes a Propagation Delay Dif-

ference (PDD) specification intended to help designers

minimize “dead time” in their power inverter designs.

Dead time is the time high and low side power transistors

are off. Any overlap in Ql and Q2 conduction will result

in large currents flowing through the power devices

from the high voltage to the low-voltage motor rails.

To minimize dead time in a given design, the turn on of

LED2 should be delayed (relative to the turn off of LED1)

so that under worst-case conditions, transistor Q1 has

just turned off when transistor Q2 turns on, as shown in

Figure 26. The amount of delay necessary to achieve this

condition is equal to the maximum value of the propa-

gation delay difference specification, PDD max, which is

specified to be 500 ns over the operating temperature

range of -40° to 100°C.

VOUT1

VOUT2

ILED2

Q1 ON

Q2 OFF

Q1 OFF

Q2 ON

tPHL MIN

tPHL MAX

(tPHL-tPLH) MAX

tPLH

MIN

tPLH MAX

PDD* MAX

MAXIMUM DEAD TIME

(DUE TO OPTOCOUPLER)

= (tPHL MAX - tPHL MIN) + (tPLH MAX - tPLH MIN)

= (tPHL MAX - tPLH MIN) – (tPHL MIN - tPLH MAX)

= PDD* MAX – PDD* MIN

ILED1

VOUT1

Q1 ON

Q1 OFF

*PDD = PROPAGATION DELAY DIFFERENCE

NOTE: FOR DEAD TIME AND PDD CALCULATIONS ALL PROPAGATION

DELAYS ARE TAKEN AT THE SAME TEMPERATURE AND TEST CONDITIONS.

Figure 27. Waveforms for Dead Time.

VOUT2

ILED2

Q2 OFF

Q2 ON

tPHL MAX

tPLH MIN

Note that the propagation delays used to calculate PDD

and dead time are taken at equal temperatures and test

conditions since the optocouplers under consideration

are typically mounted in close proximity to each other

and are switching identical IGBTs.

PDD* MAX = (tPHL- tPLH)MAX = tPHL MAX - tPLH MIN

*PDD = PROPAGATION DELAY DIFFERENCE

NOTE: FOR PDD CALCULATIONS THE PROPAGATION DELAYS

ARE TAKEN AT THE SAME TEMPERATURE AND TEST CONDITIONS.

Figure 26. Minimum LED Skew for Zero Dead Time.

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