25. Short circuit current is the amount of
output current generated when either
output is shorted to V
DD2
or ground.
26. IMR (also known as CMR or Common
Mode Rejection) specifies the mini-
mum rate of rise of an isolation mode
noise signal at which small output
perturbations begin to appear. These
output perturbations can occur with
both the rising and falling edges of the
isolation-mode wave form and may be
of either polarity. When the perturba-
tions first appear, they occur only
occasionally and with relatively small
peak amplitudes (typically 20-30 mV
at the output of the recommended
application circuit). As the magnitude
of the isolation mode transients
increase, the regularity and amplitude
of the perturbations also increase. See
applications section for more
information.
27. IMRR is defined as the ratio of
differential signal gain (signal applied
differentially between pins 2 and 3) to
the isolation mode gain (input pins
tied to pin 4 and the signal applied
between the input and the output of
the isolation amplifier) at 60 Hz,
expressed in dB.
28. Output noise comes from two primary
sources: chopper noise and sigma-
delta quantization noise. Chopper
noise results from chopper stabiliza-
tion of the output op-amps. It occurs
at a specific frequency (typically 200
kHz at room temperature), and is not
attenuated by the internal output filter.
A filter circuit can be easily added to
the external post-amplifier to reduce
the total rms output noise. The
internal output filter does eliminate
most, but not all, of the sigma-delta
quantization noise. The magnitude of
the output quantization noise is very
small at lower frequencies (below 10
kHz) and increases with increasing
frequency. See applications section for
more information.
29. Data sheet value is the differential
amplitude of the transient at the
output of the HCPL-7800 when a
1 V
pk-pk
, 1 MHz square wave with 5 ns
rise and fall times is applied to both
V
DD1
and V
DD2
.
30. This is a two-terminal measurement:
pins 1-4 are shorted together and pins
5-8 are shorted together.
31. In accordance with UL1577, for
devices with minimum V
ISO
specified at
3750 V
rms
, each optocoupler is proof-
tested by applying an insulation test
voltage greater-than-or-equal-to 4500
V
rms
for one second (leak current
detection limit, I
I-O
< 5
µA).
This test
is performed before the method b,
100% production test for partial
discharge shown in the VDE 0884
Insulation Characteristics Table.
32. Case temperature was measured with a
thermocouple located in the center of
the underside of the package.
dV
OS
– INPUT-REFERRED OFFSET DRIFT – µV
1500
MEAN
± 2 SIGMA
1000
+5 V
+5 V
+15 V
0.1 µF
0.1 µF
1
2
3
4
HCPL-7800
8
7
6
5
0.1 µF
10 K
+
-
10 K
AD624CD
GAIN = 1000
V
OUT
500
0
-500
0.33 µF
0.33 µF
0.1 µF
-1000
-40
-20
0
20
40
60
80
100
-15 V
T
A
– TEMPERATURE – °C
Figure 1. Input Offset Voltage Test Circuit.
Figure 2. Input-Referred Offset Drift
vs. Temperature.
1-224
HP [ AGILENT(HEWLETT-PACKARD) ]
