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HCPL-7860-000E

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17
10
OFFSET CHANGE - µV
TEMPERATURE - °C
-50
-15
150
60
-150
0
V
DD1
= 4.5 V
100
-40 8510 35
V
DD1
= 5.0 V
V
DD1
= 5.5 V
-100
50
V
REF
CHANGE - %
TEMPERATURE - °C
0
-15
0.8
60
-0.4
0.2
V
DD1
= 4.5 V
0.6
-40 8510 35
V
DD1
= 5.0 V
V
DD1
= 5.5 V
-0.2
0.4
SNR
TEMPERATURE - °C
64
62
-15
68
60
61
65
V
DD1
= 4.5 V
67
-40 8510 35
V
DD1
= 5.0 V
V
DD1
= 5.5 V
63
66
SNR
CONVERSION MODE #
60
2
80
4
45
70
5
75
55
50
65
31
EFFECTIVE RESOLUTION (# BITS)
CONVERSION MODE #
11
2
14
3
8
12
1
13
10
9
4 5
CONVERSION TIME - µs
CONVERSION MODE #
100
80
2
200
3
0
140
PRE-TRIGGER MODE 2
180
1
160
120
60
40
20
PRE-TRIGGER MODE 0
PRE-TRIGGER MODE 1
4 5
Figure 10. SNR vs. Conversion Mode.
Figure 11. Eective Resolution vs. Conversion Mode. Figure 12. Conversion Time vs. Conversion Mode.
Figure 7. Oset Change vs. Temperature Figure 8. V
REF
Change vs. Temperature
Figure 9. SNR vs. Temperature
11
Figure 16. Typical Application Circuit.
R
SHUNT
0.02
INPUT
CURRENT
V
DD1
ISOLATED
+ 5 V
V
IN+
V
IN-
GND1
V
DD2
MCLK
MDAT
GND2
C1
0.1 µF
+
CDAT SCLK
CCLK V
DD
CLAT CHAN
MCLK1 SDAT
MDAT1 CS
MCLK2 THR1
MDAT2 OVR1
GND RESET
NON-ISOLATED
+ 5 V
C3
10 µF
+
HCPL-7860/
HCPL-786J
3-WIRE
SERIAL
INTERFACE
C2
0.1 µF
HCPL-0872
SIGNAL DELAY - µs
CONVERSION MODE #
40
2
100
3
0
80
1
90
30
20
60
70
50
10
4 5
2 µs/DIV.
V
IN+
(200 mV/DIV.)
OVR1 (200 mV/DIV.)
THR1
(2 V/DIV.)
SIGNAL BANDWIDTH - kHz
CONVERSION MODE #
40
2
100
3
0
80
1
90
30
20
60
70
50
10
4 5
Figure 13. Signal Delay vs. Conversion Mode. Figure 14. Over-Range and Threshold Detect Times.
Figure 15. Signal Bandwidth vs. Conversion Mode.
Application Information
Digital Current Sensing
As shown in Figure 16, using the Isolated 2-chip A/D con-
verter to sense current can be as simple as connecting a
current-sensing resistor, or shunt, to the input and reading
output data through the 3-wire serial output interface.
By choosing the appropriate shunt resistance, any range
of current can be monitored, from less than 1 A to more
than 100 A.
Even better performance can be achieved by fully utilizing
the more advanced features of the Isolated A/D converter,
such as the pre-trigger circuit, which can reduce conver-
sion time to less than 1 µs, the fast over-range detector
for quickly detecting short circuits, dierent conversion
modes giving various resolution/speed trade-os, oset
calibration mode to eliminate initial oset from measure-
ments, and an adjustable threshold detector for detecting
non-short circuit overload conditions.
12
Product Description
The HCPL-7860/HCPL-786J Isolated Modulator (optocou-
pler) uses sigma-delta modulation to convert an analog
input signal into a high-speed (10 MHz) single-bit digital
data stream; the time average of the modulator’s single-
bit data is directly proportional to the input signal. The
isolated modulator’s other main function is to provide
galvanic isolation between the analog input and the digital
output. An internal voltage reference determines the full-
scale analog input range of the modulator (approximately
± 320 mV); an input range of ± 200 mV is recommended
to achieve optimal performance.
HCPL-7860/HCPL-786J can be used together with HCPL-
0872, Digital Interface IC or a digital lter. The primary
functions of the HCPL-0872 Digital Interface IC are to de-
rive a multi-bit output signal by averaging the single-bit
modulator data, as well as to provide a direct microcon-
troller interface. The eective resolution of the multi-bit
output signal is a function of the length of time (measured
in modulator clock cycles) over which the average is taken;
averaging over longer periods of time results in higher
resolution. The Digital Interface IC can be congured for
ve conversion modes, which have dierent combina-
tions of speed and resolution to achieve the desired level
of performance. Other functions of the HCPL-0872 Digital
Interface IC include a Phase Locked Loop based pre-trigger
circuit that can either give more precise control of the ef-
fective sampling time or reduce conversion time to less
than 1 µs, a fast over-range detection circuit that rapidly
indicates when the magnitude of the input signal is be-
yond full-scale, an adjustable threshold detection circuit
that indicates when the magnitude of the input signal is
above a user adjustable threshold level, an oset calibra-
tion circuit, and a second multiplexed input that allows a
second Isolated Modulator to be used with a single Digital
Interface IC.
The digital output format of the Isolated A/D Converter is
15 bits of unsigned binary data. The input full-scale range
and code assignment is shown in Table 1 below. Although
the output contains 15 bits of data, the eective resolution
is lower and is determined by selected conversion mode as
shown in Table 2 below.
Table 1. Input Full-Scale Range and Code Assignment.
Analog Input Voltage Input Digital Output
Full Scale Range 640 mV 32768 LSBs
Minimum Step Size 20 µV 1 LSB
+Full Scale +320 mV 111111111111111
Zero 0 mV 100000000000000
-Full Scale -320 mV 000000000000000
Table 2. Isolated A/D Converter Typical Performance Characteristics.
Conversion Mode
Signal-to-
Noise Ratio
(dB)
Eective
Resolution
(bits)
Conversion Time (µs)
Signal
Delay(µs)
Signal Band-
width (kHz)
Pre-Trigger Mode
0 1 2
1 83 13.5 205 102
0.2
102 3.4
2 79 12.8 103 51 51 6.9
3 73 11.9 39 19 19 22
4 66 10.7 20 10 10 45
5 53 8.5 10 5 5 90
Notes: Bold italic type indicates Default values.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17

HCPL-7860-000E

Mfr. #:
Buy HCPL-7860-000E
Manufacturer:
Broadcom / Avago
Description:
Data Acquisition ADCs/DACs - Specialized Isolated Modulator
Lifecycle:
New from this manufacturer.
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