HCPL-5120 Datasheet, PDF (15/16 Pages) Agilent(Hewlett-Packard) – 2.0 Amp Output Current IGBT Gate Drive Optocoupler

IPM Dead Time and Propagation
Delay Specifications.
The HCPL- 5120 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 25) 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 rail
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
33. The amount of delay
necessary to achieve this
conditions is equal to the
maximum value of the
propagation delay difference
specification, PDD_MAX, which is
specified to be 350 ns over the
operating temperature range of
- 55°C to 125°C.
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 specifications as
shown in Figure 34. The
maximum dead time for the
HCPL- 5120 is 700 ns (= 350 ns
- (- 350 ns)) over an operating
temperature range of - 55°C to
125°C.
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.
ILED1
V _OUT1
V _OUT2
Q1 ON
Q2 OFF
Q1 OFF
Q2 ON
*PDD = PROPAGATION
DELAY DIFFERENCE
NOTE:
FOR PDD CALCULATIONS
THE PROPAGATION DELAYS
ARE TAKEN AT THE SAME
TEMPERATURE AND TEST
CONDITIONS.
ILED2
tPHL MAX
tPLH MIN
PDD* MAX = (t_PHL - t_PLH)_MAX = t_{PHL MAX} - t_{PLH MIN}
Figure 33. Minimum LED Skew for Zero Dead Time
I_LED1
V_OUT1
V_OUT2
Q1 ON
Q2 OFF
Q1 OFF
Q2 ON
I_LED2
tPHL MIN
t_{PHL MAX}
tPLH MIN
(tPHL - tPLH) MAX
= PDD* MAX
tPLH 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
Figure 34. Waveforms for Dead Time Calculations
*PDD = PROPAGATION
DELAY DIFFERENCE
NOTE:
FOR DEAD TIME AND
PDD CALCULATIONS ALL
PROPAGATION DELAYS ARE
TAKEN AT THE SAME
TEMPERATURE AND TEST
CONDITIONS.
50
40
30
20
case-to-ambient thermal resistance
10
= 70 ^oC/W
= 140 ^oC/W
= 210 ^oC/W
0
-55 -25 5
35 65
95 125
TA - AMBIENT TEMPERATURE - ^oC
300
250
200
150
100 ^{case-to-ambient thermal resistance}
= 70 ^oC/W
= 140 ^oC/W
50
= 210 ^oC/W
0
-55 -25 5 35 65 95 125
T_A - AMBIENT TEMPERATURE - ^oC
Figure 35. Input Thermal Derating Curve,
Dependence of case-to-ambient Thermal
Resistance
Figure 36. Output Thermal Derating Curve,
Dependence of case-to-ambient Thermal
Resistance
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