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 flexible
because the LED and both photodiodes are accessible
to the designer. This allows the designer to make perf‑
ormance trade‑offs that would otherwise be difficult to
make with commercially available isolation amplifiers
(e.g., bandwidth vs. accuracy vs. cost). Analog isolation
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
simplified circuit topologies illustrating the design flex‑
ibility of the HCNR200/201 are discussed below.
The circuit in Figure 12a is configured 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 implement
other circuit configurations 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
combination of positive and negative voltages, allowing
for both inverting and non‑inverting circuits.
All of the configurations described above are unipolar
(single polarity); the circuits cannot accommodate 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 amplifier. Two topologies
that allow for bipolar operation are shown in Figure 14.
The circuit in Figure 14a uses two current sources to
offset 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 offset of zero. Current sources I
I
suitable voltage sources.
The circuit in Figure 14b uses two optocouplers to obtain
bipolar operation. The first optocoupler handles the pos‑
itive voltage excursions, while the second optocoupler
handles the negative ones. The output photodiodes are
connected in an antiparallel configuration so that they
produce output signals of opposite polarity.
The first circuit has the obvious advantage of requiring
only one optocoupler; however, the offset performance
of the circuit is dependent on the matching of I
I
Changes in the gain of the optocoupler will directly af‑
fect the offset of the circuit.
The offset performance of the second circuit, on the
other hand, is much more stable; it is independent 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 offset of opposite polarity to ob‑
PD1
is always positive. The second current
OS1
provides enough offset
OS1
OS1
and
and
to worry about. However, the second circuit requires two
optocouplers, separate gain adjustments for the posi‑
tive and negative portions of the signal, and can exhibit
crossover distortion near zero volts. The correct circuit to
choose for an application would depend on the require‑
ments of that particular application. As with the basic
isolation amplifier circuit in Figure 12a, the circuits in Fig‑
ure 14 are simplified and would require a few additional
components to function properly. Two example circuits
that operate with bipolar input signals are discussed in
the next section.
As a final example of circuit design flexibility, the simpli‑
fied schematics in Figure 15 illustrate 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 amplifier, 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 amplifier 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 characteristics of the LED.
The 4‑20 mA transmitter circuit in Figure 15b is a little dif‑
ferent from the previous circuits, particularly 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 flows 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