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.
maximum and minimum propaga-
tion delay difference specifica-
tions as shown in Figure 35. The
maximum dead time for the
HCPL-3120 is 700 ns (= 350 ns -
(-350 ns)) over an operating
temperature range of -40°C to
100°C.
14
12
I
LED1
V
OUT1
(12.3, 10.8)
Q1 ON
10
8
(10.7, 9.2)
Q1 OFF
Q2 ON
6
Q2 OFF
V
OUT2
4
I
LED2
2
0
t
PHL MAX
(10.7, 0.1)
(12.3, 0.1)
15
t
PLH MIN
0
5
10
20
PDD* MAX = (t - t
)
= t
- t
PHL MAX PLH MIN
PHL PLH MAX
(V
- V
) – SUPPLY VOLTAGE – V
EE
CC
*PDD = PROPAGATION DELAY DIFFERENCE
NOTE: FOR PDD CALCULATIONS THE PROPAGATION DELAYS
ARE TAKEN AT THE SAME TEMPERATURE AND TEST CONDITIONS.
Figure 34. Minimum LED Skew for Zero Dead Time.
Figure 36. Under Voltage Lock Out.
I
800
LED1
P
(mW)
(mA)
S
700
600
500
400
300
I
S
V
OUT1
Q1 ON
Q1 OFF
Q2 ON
Q2 OFF
V
OUT2
200
100
0
I
LED2
t
PHL MIN
t
PHL MAX
t
PLH
MIN
0
25 50 75 100 125 150 175 200
– CASE TEMPERATURE – °C
T
S
t
PLH MAX
(t
t
)
PHL- PLH MAX
Figure 37. Thermal Derating Curve,
Dependence of Safety Limiting Value
with Case Temperature per VDE 0884.
PDD* MAX
MAXIMUM DEAD TIME
(DUE TO OPTOCOUPLER)
= (t
- t
) + (t
- t )
PLH MAX PLH MIN
PHL MAX PHL MIN
= (t
- t
) – (t
- t
)
PHL MAX PLH MIN PHL MIN PLH MAX
= 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.
Figure 35. Waveforms for Dead Time.
1-196
HP [ HEWLETT-PACKARD ]
