HCPL316J datasheet(33/33 Pages) HP

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Figure 80. Minimum LED Skew for Zero Dead Time.

Figure 81. Waveforms for Dead Time Calculation.

tPHLMAX

tPLHMIN

PDD* MAX = (tPHL- tPLH)MAX = tPHLMAX - tPLHMIN

*PDD = PROPAGATION DELAY

NOTE: FOR PDD CALCULATIONS THE PROPAGATION DELAYS

ARE TAKEN AT THE SAME TEMPERATURE AND TEST CONDITIONS.

VOUT1

VIN+2

VOUT2

VIN+1

Q1 ON

Q2 OFF

Q1 OFF

Q2 ON

tPLHMIN

MAXIMUM DEAD TIME

(DUE TO OPTOCOUPLER)

= (tPHLMAX - tPHLMIN) + (tPLHMAX - tPLHMIN)

= (tPHLMAX - tPLHMIN) – (tPHLMIN - tPLHMAX)

= PDD*MAX – PDD*MIN

*PDD = PROPAGATION DELAY DIFFERENCE

NOTE: FOR DEAD TIME AND PDD CALCULATIONS ALL PROPAGATION

DELAYS ARE TAKEN AT THE SAME TEMPERATURE AND TEST CONDITIONS.

VOUT1

VIN+2

VOUT2

VIN+1

Q1 ON

Q2 OFF

Q1 OFF

Q2 ON

tPHLMIN

tPHLMAX

tPLHMAX

= PDD*MAX

(tPHL-tPLH)MAX

System Considerations

Propagation Delay Difference

(PDD)

The HCPL-316J includes a

Propagation Delay Difference

(PDD) 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 62) 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,

a potentially catastrophic condi-

tion that must be prevented.

To minimize dead time in a given

design, the turn-on of the

HCPL-316J driving Q2 should be

delayed (relative to the turn-off of

the HCPL-316J driving Q1) so

that under worst-case conditions,

transistor Q1 has just turned off

when transistor Q2 turns on, as

shown in Figure 80. The amount

of delay necessary to achieve this

condition is equal to the maxi-

mum value of the propagation

delay difference specification,

PDDMAX, which is specified to be

400 ns over the operating

temperature range of -40

°C to

100

°C.

Delaying the HCPL-316J turn-on

signals 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 specifications as

shown in Figure 81. The

maximum dead time for the

HCPL-316J is 800 ns (= 400 ns -

(-400 ns)) over an operating

temperature range of -40

°C to

100

°C.

Note that the propagation delays

used to calculate PDD and dead

time are taken at equal tempera-

tures and test conditions since

the optocouplers under consider-

ation are typically mounted in

close proximity to each other and

are switching identical IGBTs.

www.agilent.com/semiconductors

E-mail: SemiconductorSupport@agilent.com

Data subject to change.

Obsoletes 5989-0784EN

March 1, 2005

5989-2143EN

For product information and a complete list of

Agilent contacts and distributors, please go to

our web site.

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