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HCPL-316J Datasheet, PDF (33/33 Pages) AVAGO TECHNOLOGIES LIMITED – 2.5 Amp Gate Drive Optocoupler with Integrated (VCE) Desaturation Detection and Fault Status Feedback | |||
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System Considerations
Propagation Delay Difference (PDD)
The HCPL-316J includes a Propagation Delay Difference
(PDD) specification intended to help designers minimize
âdead timeâ 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 cata-
strophic condiÂtion 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 maxiÂmum value of the propagation delay
difference specification, PDDMAX, which is specified to
be 400âns over the operating temperature range of â40°C
to 100°C.
Delaying the HCPL-316J turn-on signals by the maximum
propagaÂtion 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 800âns (= 400âns - (-400âns)) over an operat-
ing temperature range of -40°C to 100°C.
Note that the propagation delays used to calculate PDD
and dead time are taken at equal temperaÂtures and test
conditions since the optocouplers under considerÂaÂtion
are typically mounted in close proximity to each other
and are switching identical IGBTs.
0.1
5 V + µF
â
VIN+
VIN-
VCC1
GND1
RESET
FAULT
VLED1+
VLED1-
VE
VLED2+
DESAT
VCC2
VC
VOUT
VEE
VEE
IE
0.1
µF
0.1 µF
30 V
0.1 µF
+
â
30 V
0.1
5 V + µF
â
VIN+
VIN-
VCC1
GND1
RESET
FAULT
VLED1+
VLED1-
VE
VLED2+
DESAT
VCC2
VC
VOUT
VEE
VEE
IE
0.1
µF
0.1 µF
30 V
0.1 µF
+
â
30 V
Figure 80. Minimum LED Skew for Zero Dead Time.
Figure 81. Waveforms for Dead Time Calculation.
HCPL-316J fig 60
HCPL-316J fig 61
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Data subject to change. Copyright © 2005-2009 Avago Technologies. All rights reserved. Obsoletes AV01-0579EN
AV02-0717EN - April 9, 2009
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