HCNR201-300E Avago Technologies US Inc., HCNR201-300E Datasheet - Page 17

• Manufacturer Part Number: HCNR201-300E
• Description: OPTOCOUPLER ANLG DC-1MHZ GW 8SMD
• Manufacturer: Avago Technologies US Inc.

Specifications of HCNR201-300E

• Output Type: Linear Photovoltaic
• Input Type: DC
• Package / Case: 8-SMD Gull Wing
• Number Of Channels: 1
• Voltage - Isolation: 5000Vrms
• Current Transfer Ratio (min): 0.36% @ 10mA
• Current Transfer Ratio (max): 0.72% @ 10mA
• Current - Dc Forward (if): 25mA
• Mounting Type: Surface Mount, Gull Wing
• Current Transfer Ratio: 0.36 % to 0.72 %
• Forward Current: 1 mA to 20 mA
• Isolation Voltage: 5000 Vrms
• Minimum Forward Diode Voltage: 1.2 V
• Output Device: Photodiode
• Configuration: 1 Channel
• Maximum Forward Diode Voltage: 1.95 V
• Maximum Reverse Diode Voltage: 2.5 V
• Maximum Input Diode Current: 25 mA
• Maximum Power Dissipation: 60 mW
• Maximum Operating Temperature: + 100 C
• Minimum Operating Temperature: - 55 C
• No. Of Channels: 1
• Optocoupler Output Type: Photodiode
• Input Current: 20mA
• Output Voltage: 15V
• Opto Case Style: SMD
• No. Of Pins: 8
• Forward Voltage: 1.6V
• Rohs Compliant: Yes
• Forward Current If: 25mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Current - Output / Channel: -
• Vce Saturation (max): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 516-1609-5

Circuit Design Flexibility
Circuit design with the HCNR200/201 is very fl exible
because the LED and both photodiodes are acces sible
to the designer. This allows the designer to make perf-
ormance trade-off s that would otherwise be diffi cult to
make with commercially avail able isolation amplifi ers
(e.g., band width vs. accuracy vs. cost). Analog isola tion
circuits can be designed for applications that have either
unipolar (e.g., 0-10 V) or bipolar (e.g., ±10 V) signals, with
positive or negative input or output voltages. Several
simplifi ed circuit topologies illustrating the design fl ex-
ibility of the HCNR200/201 are discussed below.
The circuit in Figure 12a is confi gured to be non-invert-
ing with positive input and output voltages. By simply
changing the polarity of one or both of the photodiodes,
the LED, or the op-amp inputs, it is possible to imple ment
other circuit confi gu ra tions as well. Figure 13 illustrates
how to change the basic circuit to accommodate both
positive and negative input and output voltages. The in-
put and output circuits can be matched to achieve any
combina tion of positive and negative voltages, allowing
for both inverting and non-inverting circuits.
All of the confi gurations described above are unipolar
(single polar ity); the circuits cannot accom mo date a sig-
nal that might swing both positive and negative. It is pos-
sible, however, to use the HCNR200/201 optocoupler to
implement a bipolar isolation amplifi er. Two topologies
that allow for bipolar operation are shown in Figure 14.
The circuit in Figure 14a uses two current sources to
off set the signal so that it appears to be unipolar to the
optocoupler. Current source I
to ensure that I
source, I
tain a net circuit off set of zero. Current sources I
I
suitable voltage sources.
The circuit in Figure 14b uses two optocouplers to obtain
bipolar operation. The fi rst optocoupler handles the pos-
itive voltage excursions, while the second optocoupler
handles the negative ones. The output photo diodes are
connected in an antiparallel confi guration so that they
produce output signals of opposite polarity.
The fi rst circuit has the obvious advantage of requiring
only one optocoupler; however, the off set performance
of the circuit is dependent on the matching of I
I
Changes in the gain of the opto coupler will directly af-
fect the off set of the circuit.
The off set performance of the second circuit, on the
other hand, is much more stable; it is inde pendent of
optocoupler gain and has no matched current sources
17
OS2
OS2
can be implemented simply as resistors connected to
and is also dependent on the gain of the optocoupler.
OS2
, provides an off set of opposite polarity to ob-
PD1
is always positive. The second current
OS1
provides enough off set
OS1
OS1
and
and
to worry about. How ever, the second circuit requires two
optocouplers, separate gain adjustments for the posi-
tive and negative portions of the signal, and can exhibit
crossover distor tion near zero volts. The correct circuit to
choose for an applica tion would depend on the require-
ments of that particular application. As with the basic
isolation amplifi er circuit in Figure 12a, the circuits in Fig-
ure 14 are simplifi ed and would require a few additional
compo nents to function properly. Two example circuits
that operate with bipolar input signals are discussed in
the next section.
As a fi nal example of circuit design fl exibility, the simpli-
fi ed schematics in Figure 15 illus trate how to implement
4-20 mA analog current-loop transmitter and receiver
circuits using the HCNR200/201 optocoupler. An impor-
tant feature of these circuits is that the loop side of the
circuit is powered entirely by the loop current, eliminat-
ing the need for an isolated power supply.
The input and output circuits in Figure 15a are the same
as the negative input and positive output circuits shown
in Figures 13c and 13b, except for the addition of R3 and
zener diode D1 on the input side of the circuit. D1 regu-
lates the supply voltage for the input amplifi er, while R3
forms a current divider with R1 to scale the loop current
down from 20 mA to an appropriate level for the input
circuit (<50 μA).
As in the simpler circuits, the input amplifi er adjusts the
LED current so that both of its input terminals are at the
same voltage. The loop current is then divided
between R1 and R3. I
is given by the following equation:
Combining the above equation with the equations used
for Figure 12a yields an overall expression relating the
output voltage to the loop current,
Again, you can see that the relationship is constant, lin-
ear, and independent of the charac teristics of the LED.
The 4-20 mA transmitter circuit in Figure 15b is a little dif-
ferent from the previous circuits, partic ularly the output
circuit. The output circuit does not directly generate an
output voltage which is sensed by R2, it instead uses Q1
to generate an output current which fl ows through R3.
This output current generates a voltage across R3, which
is then sensed by R2. An analysis similar to the one above
yields the following expression relating output current
to input voltage:
I
V
I
PD1
LOOP
OUT
= I
/I
/V
LOOP
LOOP
IN
= K*(R2+R3)/(R1*R3).
= K*(R2*R3)/(R1+R3).
*R3/(R1+R3).
PD1
is equal to the current in R1 and