Datasheet

21
Figure 33. Recommended LED Drive Circuit for Ultra-High CMR.Figure 32. Not Recommended Open Collector Drive Circuit.
t
PHL MAX
t
PLH MIN
PDD* MAX = (t
PHL
- t
PLH
)
MAX
= t
PHL MAX
- t
PLH MIN
*PDD = PROPAGATION DELAY DIFFERENCE
NOTE: FOR PDD CALCULATIONS THE PROPAGATION DELAYS
ARE TAKEN AT THE SAME TEMPERATURE AND TEST CONDITIONS.
V
OUT1
I
LED2
V
OUT2
I
LED1
Q1 ON
Q2 OFF
Q1 OFF
Q2 ON
HCPL-3150 fig 34
Figure 34. Minimum LED Skew for Zero Dead Time.
Figure 35. Waveforms for Dead Time.
t
PLH
MIN
MAXIMUM DEAD TIME
(DUE TO OPTOCOUPLER)
= (t
PHL MAX
- t
PHL MIN
) + (t
PLH MAX
- t
PLH MIN
)
= (t
PHL MAX
- t
PLH MIN
) – (t
PHL MIN
- t
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.
V
OUT1
I
LED2
V
OUT2
I
LED1
Q1 ON
Q2 OFF
Q1 OFF
Q2 ON
HCPL-3150 fig 35
t
PHL MIN
t
PHL MAX
t
PLH MAX
= PDD* MAX
(t
PHL-
t
PLH
)
MAX
HCPL-3150 fig 32
1
3
2
4
8
6
7
5
C
LEDP
C
LEDN
SHIELD
+5 V
Q1
I
LEDN
HCPL-3150 fig 33
1
3
2
4
8
6
7
5
C
LEDP
C
LEDN
SHIELD
+5 V