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PDF HCPL7840 Data sheet ( Hoja de datos )
| Número de pieza | HCPL7840 | |
| Descripción | Analog Isolation Amplifier | |
| Fabricantes | Agilent(Hewlett-Packard) | |
| Logotipo | .gif "Agilent(Hewlett-Packard)"){kind=logo} |
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Analog Isolation Amplifier
Technical Data
H
HCPL-7840
Features
• High Common Mode
Rejection (CMR): 15 kV/µs
at VCM = 1000 V
• 5% Gain Tolerance
• 0.1% Nonlinearity
• Low Offset Voltage and Off-
set Temperature Coefficient
• 100 kHz Bandwidth
• Performance Specified Over
-40°C to 85°C Temperature
Range
• Recognized Under UL 1577
and CSA Approved for
Dielectric Withstand Proof
Test Voltage of 2500 Vac, 1
Minute
• Standard 8-Pin DIP Package
Applications
• Motor Phase and Rail
Current Sensing
• Inverter Current Sensing
• Switched Mode Power
Supply Signal Isolation
• General Purpose Current
Sensing and Monitoring
• General Purpose Analog
Signal Isolation
Description
The HCPL-7840 isolation ampli-
fier provides accurate, electrically
isolated and amplified representa-
tions of voltage and current.
When used with a shunt resistor
in the current path, the HCPL-
7840 offers superior reliability,
cost effectiveness, size and
autoinsertability compared with
the traditional solutions such as
current transformers and Hall-
effect sensors.
The HCPL-7840 consists of a
sigma-delta analog-to-digital
converter optically coupled to a
digital-to-analog converter.
Superior performance in design
critical specifications such as
common-mode rejection, offset
voltage, nonlinearity, operating
temperature range and regulatory
compliance make the HCPL-7840
the clear choice for designing
reliable, lower-cost, reduced-size
products such as motor
controllers and inverters.
environments such as those
generated by the high switching
rates of power IGBTs.
Low offset voltage together with
a low offset voltage temperature
coefficient permits accurate use
of auto-calibration techniques.
Gain tolerance of 5% with 0.1%
nonlinearity further provide the
performance necessary for
accurate feedback and control.
A wide operating temperature
range with specified performance
allows the HCPL-7840 to be used
in hostile industrial environments.
Functional Diagram
IDD1
VDD1 1
IDD2
8 VDD2
VIN+ 2
VIN– 3
+
–
+ 7 VOUT+
– 6 VOUT–
GND1 4
SHIELD
5 GND2
Common-mode rejection of
15 kV/µs makes the HCPL-7840
suitable for noisy electrical
A 0.1 F bypass capacitor must be connected between pins 1 and 4 and between pins 5 and 8.
CAUTION: It is advised that normal static precautions be taken in handling and assembly of this component to
prevent damage and/or degradation which may be induced by ESD.
1-248
5965-4784E
1 page  
AC Electrical Specifications
All specifications, typicals and figures are at the nominal operating conditions of VIN+ = 0 V, VIN- = 0 V,
TA = 25°C, VDD1 = 5 V and VDD2 = 5 V, unless otherwise noted.
Parameter Symbol Min. Typ. Max. Unit
Test Conditions
Fig.
Common Mode
Rejection
Common Mode
Rejection Ratio
at 60 Hz
CMR
CMRR
10 15
>140
kV/µs
dB
VCM = 1 kV
4.5 ≤ (VDD1, VDD2) ≤ 5.5 V
16
Propagation Delay tPD50
to 50%
Propagation Delay tPD90
to 90%
3.7 6.5 µs VIN+ = 0 to 100 mV step 17,18
-40°C ≤ TA ≤ 85°C
4.5 ≤ (VDD1, VDD2) ≤ 5.5 V
5.7 9.9
Rise/Fall Time
(10-90%)
tR/F
3.4 6.6
Small-Signal
Bandwidth
(-3 dB)
f-3 dB
50 100
kHz -40°C ≤ TA ≤ 85°C
17, 19,
4.5 ≤ (VDD1, VDD2) ≤ 5.5 V 20
Small-Signal
Bandwidth (-45°)
f-45°
33
RMS Input-
Referred Noise
VN
0.6 mVrms In recommended 21, 23
application circuit
Power Supply
Rejection
PSR
570 mVP-P
Note
8
9
10
11
Package Characteristics
All specifications, typicals and figures are at the nominal operating conditions of VIN+ = 0 V, VIN- = 0 V,
TA = 25°C, VDD1 = 5 V and VDD2 = 5 V, unless otherwise noted.
Parameter
Symbol Min. Typ. Max. Unit Test Conditions Fig. Note
Input-Output Momentary
Withstand Voltage*
VISO 2500
Vrms t = 1 min., RH ≤ 50%
12,13
Input-Output Resistance
Input-Output Capacitance
RI-O
CI-O
1012
0.6
Ω VI-O = 500 Vdc
pF f = 1 MHz
VI-O = 0 Vdc
13
*The Input-Output Momentary Withstand Voltage is a dielectric voltage rating that should not be interpreted as an input-output
continuous voltage rating. For the continuous voltage rating, refer to the VDE 0884 Insulation Characteristics Table (if applicable),
your equipment level safety specification, or HP Application Note 1074, “Optocoupler Input-Output Endurance Voltage.”
1-252
5 Page 
to help filter output noise. The
particular op-amp used in the
post-amp is not critical; however,
it should have low enough offset
and high enough bandwidth and
slew rate so that it does not
adversely affect circuit perfor-
mance. The offset of the op-amp
should be low relative to the out-
put offset of the HCPL-7840, or
less than about 5 mV.
To maintain overall circuit band-
width, the post-amplifier circuit
should have a bandwidth at least
twice the minimum bandwidth of
the isolation amplifier, or about
200 kHz. To obtain a bandwidth
of 200 kHz with a gain of 5, the
op-amp should have a gain-
bandwidth greater than 1 MHz.
The post-amplifier circuit
includes a pair of capacitors (C5
and C6) that form a single-pole
low-pass filter. These capacitors
allow the bandwidth of the post-
amp to be adjusted independently
of the gain and are useful for
reducing the output noise from
the isolation amplifier (doubling
the capacitor values halves the
circuit bandwidth). The compo-
nent values shown in Figure 23
form a differential amplifier with
a gain of 5 and a cutoff frequency
of approximately 100 kHz and
were chosen as a compromise
between low noise and fast
response times. The overall
recommended application circuit
has a bandwidth of 66 kHz, a rise
time of 5.2 µs and delay to 90%
of 8.5 µs.
The gain-setting resistors in the
post-amp should have a tolerance
of 1% or better to ensure adequate
CMRR and gain tolerance for the
overall circuit. Resistor networks
with even better ratio tolerances
can be used which offer better
performance, as well as reducing
the total component count and
board space.
The post-amplifier circuit can be
easily modified to allow for
single-supply operation. Figure
24 shows a schematic for a post
amplifier for use in 5 V single
supply applications. One addi-
tional resistor is needed and the
gain is decreased to 1 to allow
circuit operation over the full
input voltage range. See Applica-
tion Note 1078, Designing with
Hewlett-Packard Isolation
Amplifiers, for more information
on the post-amplifier circuit.
Other Information
As mentioned above, reducing the
bandwidth of the post amplifier
circuit reduces the amount of
output noise. Figure 21 shows
how the output noise changes as
a function of the post-amplifier
bandwidth. The post-amplifier
circuit exhibits a first-order low-
pass filter characteristic. For the
same filter bandwidth, a higher-
order filter can achieve even
better attenuation of modulation
noise due to the second-order
noise shaping of the sigma-delta
modulator. For more information
on the noise characteristics of the
HCPL-7840, see Application Note
1078, Designing with Hewlett-
Packard Isolation Amplifiers.
The HCPL-7840 can also be used
to isolate signals with amplitudes
larger than its recommended
input range through the use of a
resistive voltage divider at its
input. The only restrictions are
that the impedance of the divider
be relatively small (less than
1 KΩ so that the input resistance
(480 KΩ ) and input bias current
(0.6 A) do not affect the accuracy
of the measurement. An input
bypass capacitor is still required,
although the 68 Ω series damping
resistor is not (the resistance of
the voltage divider provides the
same function). The low pass
filter formed by the divider
resistance and the input bypass
capacitor may limit the
achievable bandwidth.
Table 1. Current Shunt Summary
Shunt Resistor Part Number
LVR-3.05-1%
LVR-3.02-1%
LVR-3.01-1%
LVR-5.005-1%
Shunt
Resistance
50 mΩ
20 mΩ
10 mΩ
5 mΩ
Maximum
Power
Dissipation
3W
3W
3W
5W
Maximum
Average
Current
3A
8A
15 A
35 A
Maximum
Horsepower
Range
0.8-3.0 hp
2.2-8.0 hp
4.1-15 hp
9.6-35 hp
1-258
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| PDF Descargar | [ Datasheet HCPL7840.PDF ] | |
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