Description
The HCPL-7860/HCPL-786J Optically Isolated Modulator
and HCPL-0872 Digital Interface IC or digital lter together
form an isolated programmable two-chip analog-to-digital
converter. The isolated modulator allows direct measure-
ment of motor phase currents in power inverters.
In operation, the HCPL-7860/HCPL-786J Isolated Modula-
tor converts a low-bandwidth analog input into a high-
speed one-bit data stream by means of a Sigma-Delta
(6') over-sampling modulator. This modulation provides
for high noise margins and excellent immunity against
isolation-mode transients. The modulator data and on-
chip sampling clock are encoded and transmitted across
the isolation boundary where they are recovered and de-
coded into separate high-speed clock and data channels.
NOTE: A 0.1 F bypass capacitor must be connected between pins VDD1 and GND1 and between pins VDD2 and GND2.
SIGMA
DELTA
MOD./
ENCODE
DECODE
1
2
3
4
8
7
6
5
Input
Current
HCPL-0872
or
Digital Filter
MCU
or
DSP
HCPL-7860
HCPL-7860/HCPL-786J
Optically Isolated Sigma-Delta (S-D) Modulator
Data Sheet
Features
x12-bit Linearity
x200 ns Conversion Time
(Pre-Trigger Mode 2 with HCPL-0872)
x12-bit Eective Resolution with 5 Ps Signal Delay
(14-bit with 102 Ps) (with HCPL-0872)
xFast 3 Ps Over-Range Detection (with HCPL-0872)
x± 200 mV Input Range with Single 5 V Supply
x1% Internal Reference Voltage Matching
xOset Calibration (with HCPL-0872)
x-40°C to +85°C Operating Temperature Range
x15 kV/Ps Isolation Transient Immunity
xSafety Approval: UL 1577, CSA and IEC/EN/DIN EN
60747-5-2
Applications
x Motor Phase and Rail Current Sensing
x Data Acquisition Systems
x Industrial Process Control
x Inverter Current Sensing
x General Purpose Current Sensing and Monitoring
Lead (Pb) Free
RoHS 6 fully
compliant
RoHS 6 fully compliant options available;
-xxxE denotes a lead-free product
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.
2
Pin Description
Symbol Description Symbol Description
VDD1 Supply voltage input (4.5 V to 5.5 V) VDD2 Supply voltage input (4.5 V to 5.5 V)
VIN+ Positive input (± 200 mV recommended) MCLK Clock output (10 MHz typical)
VIN- Negative input (normally connected to GND1) MDAT Serial data output
GND1 Input ground GND2 Output ground
HCPL-7860
1
2
3
4
8
7
6
5
VDD1
VIN+
VIN-
GND1
VDD2
MCLK
MDAT
GND2
SHIELD
ISOLATION
BOUNDARY
DECODE
SIGMA-
DELTA
MOD./
ENCODE
5
6
12
11
NC
NC
NC
MDAT
710
NC NC
89
GND1 GND2
1
2
16
15
VDD1
VIN+
GND2
NC
314
VIN- VDD2
413
NC MCLK
SIGMA-
DELTA
MOD./
ENCODER
DECODER
HCPL-786J
Ordering Information
HCPL-7860 is UL Recognized with 3750 Vrms for 1 minute per UL1577. HCPL-786J is UL Recognized with 5000 Vrms for
1 minute per UL1577.
Part number
Option
Package
Surface
Mount
Gull
Wing
Tape
& Reel
IEC/EN/DIN EN
60747-5-2 Quantity
RoHS
Compliant
Non-RoHS
Compliant
HCPL-7860 -000E No option 300 mil
DIP-8
X 50 per tube
-300E #300 X X X 50 per tube
-500E #500 X X X X 1000 per reel
HCPL-786J -000E No option SO-16 X 45 per tube
-500E #500 X X X 850 per reel
To order, choose a part number from the part number column and combine with the desired option from the option
column to form an order entry.
Example 1:
HCPL-7860-500E to order product of Gull Wing Surface Mount package in Tape and Reel packaging with IEC/EN/DIN
EN 60747-5-2 Safety Approval in RoHS compliant.
Example 2:
HCPL-786J to order product of SO-16 package in tube packaging and non-RoHS compliant.
Option datasheets are available. Contact your Avago sales representative or authorized distributor for information.
Remarks: The notation ‘#XXX’ is used for existing products, while (new) products launched since 15th July 2001 and RoHS
compliant option will use ‘-XXXE’.
Note: NC = No connection. Leave oating.
3
Package Outline Drawings
8-pin DIP Package
9.80 ± 0.25
(0.386 ± 0.010)
PIN ONE
1.78 (0.070) MAX.
1.19 (0.047) MAX.
A 7860X
YYWW
DATE CODE
0.51 (0.020) MIN.
0.65 (0.025) MAX.
4.70 (0.185) MAX.
2.92 (0.115) MIN.
5° TYP.
7.62 ± 0.25
(0.300 ± 0.010)
5678
4321
REFERENCE VOLTAGE
MATCHING SUFFIX*
TYPE NUMBER
3.56 ± 0.13
(0.140 ± 0.005)
6.35 ± 0.25
(0.250 ± 0.010)
0.20 (0.008)
0.33 (0.013)
2.54 ± 0.25
(0.100 ± 0.010)
1.080 ± 0.320
(0.043 ± 0.013)
DIMENSIONS IN MILLIMETERS AND (INCHES).
NOTE: FLOATING LEAD PROTRUSION IS 0.5 mm (20mils) MAX.
NOTE: INITIAL OR CONTINUED VARIATION IN THE COLOUR OF THE HCPL-7860/HCPL-786J’S WHITE MOLD
COMPOUND ISNORMAL AND DOES NOT AFFECT DEVICE PERFORMANCE OR RELIABILITY.
*ALL UNITS WITHIN EACH HCPL-7860 STANDARD PACKAGING INCREMENT (EITHER 50 PER TUBE OR 1000 PER
REEL) HAVEA COMMON MARKING SUFFIX TO REPRESENT A REFERENCE VOLTAGE MATCHING OF ± 1%. AN
ABSOLUTEREFERENCE VOLTAGE TOLERANCE OF ± 4% IS GUARANTEED BETWEEN STANDARD PACKAGING
INCREMENTS.
4
8-pin Gull Wing Surface Mount Option 300
16-Lead Surface Mount
0.635 ± 0.25
(0.025 ± 0.010) 12° NOM.
9.65 ± 0.25
(0.380 ± 0.010)
0.51 ± 0.130
(0.020 ± 0.005)
7.62 ± 0.25
(0.300 ± 0.010)
5
6
7
8
4
3
2
1
9.80 ± 0.25
(0.386 ± 0.010)
6.350 ± 0.25
(0.250 ± 0.010)
1.016 (0.040)
1.27 (0.050)
10.9 (0.430)
2.0 (0.080)
LAND PATTERN RECOMMENDATION
1.080 ± 0.320
(0.043 ± 0.013)
3.56 ± 0.13
(0.140 ± 0.005)
1.780
(0.070)
MAX.
1.19
(0.047)
MAX.
2.540
(0.100)
BSC
0.20 (0.008)
0.33 (0.013)
NOTE: FLOATING LEAD PROTRUSION IS 0.15 mm (6 mils) MAX.
DIMENSIONS IN MILLIMETERS (INCHES).
TOLERANCES (UNLESS OTHERWISE SPECIFIED): xx.xx = 0.01
xx.xxx = 0.005
LEAD COPLANARITY
MAXIMUM: 0.102 (0.004)
9
7.493 ± 0.254
(0.295 ± 0.010)
10111213141516
87654321
0.457
(0.018)
3.505 ± 0.127
(0.138 ± 0.005)
9°
10.312 ± 0.254
(0.406 ± 0.10)
10.363 ± 0.254
(0.408 ± 0.010)
0.025 MIN.
0.203 ± 0.076
(0.008 ± 0.003)
STANDOFF
8.763 ± 0.254
(0.345 ± 0.010)
0-8°
0.457
(0.018)
1.270
(0.050)
ALL LEADS
TO BE
COPLANAR
± 0.002
A 786J
YYWW
TYPE NUMBER
DATE CODE
DIMENSIONS IN MILLIMETERS AND (INCHES).
NOTE: Initial and continued variation in the color of the HCPL-786J's white mold compound is normal
and does not aect device performance or reliability.
NOTE: FLOATING LEAD PROTRUSION IS 0.15 mm (6 mils) MAX.
11.63 (0.458)
2.16 (0.085)
0.64 (0.025)
LAND PATTERN RECOMMENDATION
5
Solder Reow Temperature Prole
Recommended Lead Free IR Prole
217˚C
RAMP-DOWN
6˚C/SEC. MAX.
RAMP-UP
3˚C/SEC. MAX.
150 - 200˚C
260 +0/-5˚C
t 25˚C to PEAK
60 to 150 SEC.
20-40 SEC.
TIME WITHIN 5˚C of ACTUAL
PEAK TEMPERATURE
tp
t
s
PREHEAT
60 to 180 SEC.
t
L
T
L
T
smax
T
smin
25
T
p
TIME (SECONDS)
TEMPERATURE (˚C)
NOTES:
THE TIME FROM 25˚C to PEAK TEMPERATURE = 8 MINUTES MAX.
T
smax
= 200˚C, T
smin
= 150˚C
UL
Approval under UL 1577, component recognition pro-
gram. File E55361.
CSA
Approval under CSA Component Acceptance Notice #5,
File CA 88324.
IEC/EN/DIN EN 60747-5-2
Approved under:
IEC 60747-5-2:1997 + A1:2002
EN 60747-5-2:2001 + A1:2002
DIN EN 60747-5-2
(VDE 0884 Teil 2):2003-01.
Regulatory Information
The HCPL-7860/HCPL-786J has been approved by the following organizations:
0
TIME (SECONDS)
TEMPERATURE (˚C)
200
100
50 150100 200 250
300
0
30
SEC.
50 SEC.
30
SEC.
160˚C
140˚C
150˚C
PEAK
TEMP.
245˚C
PEAK
TEMP.
240˚C
PEAK
TEMP.
230˚C
SOLDERING
TIME
200˚C
PREHEATING TIME
150˚C, 90 + 30 SEC.
2.5˚C ± 0.5˚C/SEC.
3˚C + 1˚C/-0.5˚C
TIGHT
TYPICAL
LOOSE
ROOM
TEMPERATURE
PREHEATING RATE 3˚C + 1˚C/-0.5˚C/SEC.
REFLOW HEATING RATE 2.5˚C ± 0.5˚C/SEC.
Note: Use of non-chlorine-activated uxes is highly recommended.
Note: Use of non-chlorine-activated uxes is highly recommended.
6
Notes:
1. Insulation characteristics are guaranteed only within the safety maximum ratings, which must
be ensured by protective circuits within the application. Surface Mount Classications is Class
A in accordance with CECC00802.
2. Refer to the optocoupler section of the Isolation and Control Components Designer’s Catalog,
under Product Safety Regulations section, (IEC/EN/DIN EN 60747-5-2) for a detailed descrip-
tion of Method a and Method b partial discharge test proles.
3. Refer to the following gure for dependence of PS and IS on ambient temperature.
IEC/EN/DIN EN 60747-5-2 Insulation Characteristics[1]
Description Symbol HCPL-7860 HCPL-786J Unit
Installation classication per DIN VDE 0110/1.89, Table 1
for rated mains voltage d 300 Vrms
for rated mains voltage d 450 Vrms
for rated mains voltage d 600 Vrms
for rated mains voltage d 1000 Vrms
I - IV
I - III
I - III
I - II
I - IV
I - IV
I - IV
I - III
Climatic Classication 40/85/21 40/85/21
Pollution Degree (DIN VDE 0110/1.89) 2 2
Maximum Working Insulation Voltage VIORM 891 1230 Vpeak
Input to Output Test Voltage, Method b [2]
VIORM x 1.875=VPR, 100% Production Test with tm=1 sec,
Partial discharge < 5 pC
VPR 1670 2306 Vpeak
Input to Output Test Voltage, Method a[2]
VIORM x 1.6=VPR, Type and Sample Test, tm=10 sec,
Partial discharge < 5 pC
VPR 1425 1968 Vpeak
Highest Allowable Overvoltage(Transient Overvoltage tini = 60 sec) VIOTM 6000 8000 Vpeak
Safety-limiting values - maximum values allowed in the event of a failure.
Case Temperature
Input Current [3]
Output Power [3]
TS
IS, INPUT
PS, OUTPUT
175
400
600
175
400
600
°C
mA
mW
Insulation Resistance at TS, VIO = 500 V RS>109>109:
Insulation and Safety Related Specications
Option 300 - surface mount classication is Class A in accordance with CECC 00802.
Parameter Symbol DIP-8 SO-16 Units Conditions
Minimum External Air Gap
(Clearance)
L(101) 7.4 8.3 mm Measured from input terminals to output terminals,
shortest distance through air.
Minimum External Tracking
(Creepage)
L(102) 8.0 8.3 mm Measured from input terminals to output terminals,
shortest distance path along body.
Minimum Internal Plastic
Gap (Internal Clearance)
0.5 0.5 mm Through insulation distance conductor to conductor,
usually the straight line distance thickness between
the emitter and detector.
Tracking Resistance
(Comparative Tracking
Index)
CTI >175 >175 V DIN IEC 112/VDE 0303 Part 1
Isolation Group IIIa IIIa Material Group (DIN VDE 0110, 1/89, Table 1)
OUTPUT POWER - P
S
, INPUT CURRENT - I
S
0
0
T
S
- CASE TEMPERATURE -
o
C
20050
400
12525 75 100 150
600
800
200
100
300
500
700
175
P
S
(mW)
I
S
(mA)
7
Absolute Maximum Ratings
Parameter Symbol Min. Max. Units Note
Storage Temperature TS-55 125 °C
Ambient Operating Temperature TA-40 85 °C
Supply Voltages VDD1, VDD2 0 5.5 V
Steady-State Input Voltage VIN+, VIN- -2.0 VDD1 + 0.5 V 1
Two Second Transient Input Voltage -6.0
Output Voltages MCLK, MDAT -0.5 VDD2 + 0.5 V
Lead Solder Temperature 260°C for 10 sec., 1.6 mm below seating plane
Solder Reow Temperature Prole See Maximum Solder Reow Thermal Prole section
Recommended Operating Conditions
Parameter Symbol Min. Max. Units Note
Ambient Operating Temperature TA-40 +85 °C
Supply Voltages VDD1, VDD2 4.5 5.5 V
Input Voltage VIN+, VIN- -200 +200 mV 1
Electrical Specications (DC)
Unless otherwise noted, all specications are at VIN+ = 0 V and VIN- = 0 V, all Typical specications are at TA = 25°C and
VDD1 = VDD2 = 5 V, and all Minimum and Maximum specications apply over the following ranges: TA = -40°C to +85°C,
VDD1 = 4.5 to 5.5 V and VDD2 = 4.5 to 5.5 V.
Parameter Symbol Min. Typ. Max. Units Conditions Fig. Note
Average Input Bias Current IIN -0.8 µA 1 3
Average Input Resistance RIN 450 k :3
Input DC Common-Mode
Rejection Ratio
CMRRIN 60 dB 4
Output Logic High Voltage VOH 3.9 4.9 V IOUT = -100 µA
Output Logic Low Voltage VOL 0.1 0.6 V IOUT = 1.6 mA
Output Short Circuit Current |IOSC|30 mAV
OUT = VDD2
or GND2
5
Input Supply Current IDD1 10 15 mA VIN+ = -350 mV
to +350 mV
2
Output Supply Current IDD2 10 15 mA 3
Output Clock Frequency fCLK 8.2 10 13.2 MHz 4
Data Hold Time tHDDAT 15 ns 6
8
Electrical Specications (Tested with HCPL-0872 or Sinc3 Filter)
Unless otherwise noted, all specications are at VIN+ = -200 mV to +200 mV and VIN- = 0 V; all Typical specications are
at TA = 25°C and VDD1 = VDD2 = 5 V, and all Minimum and Maximum specications apply over the following ranges: TA =
-40°C to +85°C, VDD1 = 4.5 to 5.5 V and VDD2 = 4.5 to 5.5 V.
STATIC CHARACTERISTICS
Parameter Symbol Min. Typ. Max. Units Conditions Fig. Note
Resolution 15 bits 7
Integral Nonlinearity INL 3 30 LSB 5 8
0.01 0.14 % 6 8
Dierential Nonlinearity DNL 1 LSB 9
Uncalibrated Input Oset VOS -3 0 3 mV VIN+ = 0 V 7
Oset Drift vs. Temperature dVOS/dTA2 10 µV/°C VIN+ = 0 V 7 10
Oset drift vs. VDD1 dVOS/dVDD1 0.12 mV/V VIN+ = 0 V 7
Internal Reference Voltage VREF 320 mV 8
Absolute Reference Voltage Tolerance -4 4 % 8 2
Reference Voltage
Matching
HCPL-7860 -1 1 % TA = 25°C. 8 2
HCPL-786J -2 2 %
VREF Drift vs. Temperature dVREF/dTA60 ppm/°C. 8
VREF Drift vs. VDD1 dVREF/dVDD1 0.2 % 8
Full Scale Input Range -VREF +VREF mV 11
Recommended Input Voltage Range -200 +200 mV
DYNAMIC CHARACTERISTICS (Digital Interface IC HCPL-0872 is set to Conversion Mode 3.)
Parameter Symbol Min. Typ. Max. Units Conditions Fig. Note
Signal-to-Noise Ratio SNR 62 73 dB VIN+ = 35 Hz,
400 mVpk-pk
(141 mVrms)
sine wave.
9,10
Total Harmonic Distortion THD -67 dB
Signal-to-(Noise + Distortion) SND 66 dB
Eective Number of Bits ENOB 10 12 bits 11 12
Conversion Time tC2 0.2 0.8 µs Pre-Trigger Mode 2 1,12 13
tC1 19 23 µs Pre-Trigger Mode 1 1,12 13
tC0 39 47 µs Pre-Trigger Mode 0 1,12
Signal Delay tDSIG 19 23 µs 13 14
Over-Range Detect Time tOVR1 2.0 3.0 4.2 µs VIN+ = 0 to 400mV
step waveform
14 15
Threshold Detect Time (default
conguration)
tTHR1 10 µs 16
Signal Bandwidth BW 18 22 kHz 15 17
Isolation Transient Immunity CMR 15 20 kV/µs VISO = 1 kV 18
9
Package Characteristics
Parameter Symbol Device Min. Typ. Max. Units Conditions Note
Input-Output Momentary
Withstand Voltage*
VISO HCPL-7860 3750 Vrms RH ≤ 50%, t = 1 min;
TA = 25°C
19, 20
HCPL-786J 5000
Input-Output Resistance RI-O 1012 1013 :VI-O = 500 Vdc 20
1011 TA = 100°C
Input-Output Capacitance CI-O 1.4 pF f = 1 MHz 20
Input IC Junction-to-Case
Thermal Resistance
Tjci 96 °C/W Thermocouple located at center
underside of package
Output IC Junction-to-Case
Thermal Resistance
Tjco 114 °C/W
*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 IEC/EN/DIN EN 60747-5-2 Insulation Characteristics Table (if applicable), your equipment level
safety specication, or Avago Technologies Application Note 1074, “Optocoupler Input-Output Endurance Voltage.”
Notes:
1. If VIN- (pin 3) is brought above VDD1 - 2 V with respect to GND1 an internal optical-coupling test mode may be activated. This test mode is not
intended for customer use.
2. All units within each HCPL-7860 standard packaging increment (either 50 per tube or 1000 per reel) have a Reference Voltage Matching of ± 1%.
An Absolute Reference Voltage Tolerance of ± 4% is guaranteed between standard packaging increments.
3. Because of the switched-capacitor nature of the isolated modulator, time averaged values are shown.
4. CMRRIN is dened as the ratio of the gain for dierential inputs applied between VIN+ and VIN- to the gain for common-mode inputs applied to both
VIN+ and VIN- with respect to input ground GND1.
5. Short-circuit current is the amount of output current generated when either output is shorted to VDD2 or GND2. Use under these conditions is not
recommended.
6. Data hold time is amount of time that the data output MDAT will stay stable following the rising edge of output clock MCLK.
7. Resolution is dened as the total number of output bits. The useable accuracy of any A/D converter is a function of its linearity and signal-to-noise
ratio, rather than how many total bits it has.
8. Integral nonlinearity is dened as one-half the peak-to-peak deviation of the best-t line through the transfer curve for VIN+ = -200 mV to +200 mV,
expressed either as the number of LSBs or as a percent of measured input range (400 mV).
9. Dierential nonlinearity is dened as the deviation of the actual dierence from the ideal dierence between midpoints of successive output codes,
expressed in LSBs.
10. Data sheet value is the average magnitude of the dierence in oset voltage from TA =25°C to TA= 85°C, expressed in microvolts per °C. Three
standard deviation from typical value is less than 6 PV/°C.
11. Beyond the full-scale input range the output is either all zeroes or all ones.
12. The eective number of bits (or eective resolution) is dened by the equation ENOB = (SNR-1.76)/6.02 and represents the resolution of an ideal,
quantization-noise limited A/D converter with the same SNR.
13. Conversion time is dened as the time from when the convert start signal CS is brought low to when SDAT goes high, indicating that output data
is ready to be clocked out. This can be as small as a few cycles of the isolated modulator clock and is determined by the frequency of the isolated
modulator clock and the selected Conversion and Pre-Trigger modes. For determining the true signal delay characteristics of the A/D converter for
closed-loop phase margin calculations, the signal delay specication should be used.
14. Signal delay is dened as the eective delay of the input signal through the Isolated A/D converter. It can be measured by applying a -200 mV to
± 200 mV step at the input of modulator and adjusting the relative delay of the convert start signal CS so that the output of the converter is at mid
scale. The signal delay is the elapsed time from when the step signal is applied at the input to when output data is ready at the end of the conver-
sion cycle. The signal delay is the most important specication for determining the true signal delay characteristics of the A/D converter and should
be used for determining phase margins in closed-loop applications. The signal delay is determined by the frequency of the modulator clock and
which Conversion Mode is selected, and is independent of the selected Pre-Trigger Mode and, therefore, conversion time.
15. The minimum and maximum overrange detection time is determined by the frequency of the channel 1 isolated modulator clock.
16. The minimum and maximum threshold detection time is determined by the user-dened conguration of the adjustable threshold detection circuit
and the frequency of the channel 1 isolated modulator clock. See the Applications Information section for further detail. The specied times apply
for the default conguration.
17. The signal bandwidth is the frequency at which the magnitude of the output signal has decreased 3 dB below its low-frequency value. The signal
bandwidth is determined by the frequency of the modulator clock and the selected Conversion Mode.
18. The isolation transient immunity (also known as Common-Mode Rejection) species the minimum rate-of-rise of an isolation-mode signal applied
across the isolation boundary beyond which the modulator clock or data signals are corrupted.
19. In accordance with UL1577, for devices with minimum VISO specied at 3750 Vrms(HCPL-7860) or 5000 Vmrs (HCPL-786J) , each isolated modulator
(optocoupler) is proof-tested by applying an insulation test voltage greater than 4500 Vrms (HCPL-7860) or 6000 Vrms (HCPl-786J) for one second.
This test is performed before the Method b, 100% production test for partial discharge shown in IEC/EN/DIN EN 60747-5-2 Insulation Characteristics
Table.
20. This is a two-terminal measurement: pins 1-4 are shorted together and pins 5-8 are shorted together.
10
Figure 1. IIN vs. VIN. Figure 2. IDD1 vs. VIN.
Figure 3. IDD2 vs. VIN. Figure 4. Clock Frequency vs. Temperature.
Figure 5. INL (Bits) vs. Temperature Figure 6. INL (%) vs. Temperature
IIN - mA
VIN - V
-4
-5
-4
1
0
-9
-2
0
-6 6-2 2
-1
-3
-8
-6
-7
4
IDD1 - mA
VIN - mV
9.0
8.5
-200
10.5
200
8.0
9.5
-40 °C
10.0
-400 4000
25 °C
85 °C
IDD2 - mA
VIN - mV
8.6
8.2
-200
9.4
200
8.0
8.8
-40 °C
9.2
-400 4000
25 °C
85 °C
8.4
9.0
CLOCK FREQUENCY - MHz
TEMPERATURE - °C
9.2
-15
10.0
60
8.6
9.4
9.8
-40 8510 35
8.8
9.0
9.6
VDD1 = 4.5 V
VDD1 = 5.0 V
VDD1 = 5.5 V
INL-LSB
TEMPERATURE - °C
4
-15
7
60
2
5
VDD1 = 4.5 V
6
-40 8510 35
VDD1 = 5.0 V
VDD1 = 5.5 V
3
INL-%
TEMPERATURE - °C
0.012
-15
0.02
60
0.006
0.014
VDD1 = 4.5 V
0.016
-40 8510 35
VDD1 = 5.0 V
VDD1 = 5.5 V
0.008
0.018
0.01
11
Figure 10. SNR vs. Conversion Mode.
Figure 11. Eective Resolution vs. Conversion Mode. Figure 12. Conversion Time vs. Conversion Mode.
Figure 7. Oset Change vs. Temperature Figure 8. VREF Change vs. Temperature
Figure 9. SNR vs. Temperature
OFFSET CHANGE - μV
TEMPERATURE - °C
-50
-15
150
60
-150
0
VDD1 = 4.5 V
100
-40 8510 35
VDD1 = 5.0 V
VDD1 = 5.5 V
-100
50
VREF CHANGE - %
TEMPERATURE - °C
0
-15
0.8
60
-0.4
0.2
VDD1 = 4.5 V
0.6
-40 8510 35
VDD1 = 5.0 V
VDD1 = 5.5 V
-0.2
0.4
SNR
TEMPERATURE - °C
64
62
-15
68
60
61
65
VDD1 = 4.5 V
67
-40 8510 35
VDD1 = 5.0 V
VDD1 = 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
45
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
45
12
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 Ps, the fast over-range detector
for quickly detecting short circuits, dierent conversion
modes giving various resolution/speed trade-os, oset
calibration mode to eliminate initial oset from measure-
ments, and an adjustable threshold detector for detecting
non-short circuit overload conditions.
Figure 16. Typical Application Circuit.
RSHUNT
0.02
INPUT
CURRENT
VDD1
ISOLATED
+ 5 V
VIN+
VIN-
GND1
VDD2
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
Figure 13. Signal Delay vs. Conversion Mode. Figure 14. Over-Range and Threshold Detect Times.
Figure 15. Signal Bandwidth vs. Conversion Mode.
SIGNAL DELAY - μs
CONVERSION MODE #
40
2
100
3
0
80
1
90
30
20
60
70
50
10
45 2 μs/DIV.
VIN+ (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
45
13
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 eective 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 congured for
ve conversion modes, which have dierent 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 Ps, 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 oset 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 eective 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)
Eective
Resolution
(bits)
Conversion Time (μs)
Signal
Delay(μs)
Signal Band-
width (kHz)
Pre-Trigger Mode
012
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.
14
Figure 17. Recommended Application Circuit.
+-
MOTOR
HV-
HV+
R
SENSE
FLOATING
POSITIVE
SUPPLY
GATE DRIVE
CIRCUIT
V
DD1
V
IN+
V
IN-
GND1
V
DD2
MCLK
MDAT
GND2
CDAT SCLK
CCLK V
DD
CLAT CHAN
MCLK1 SDAT
MDAT1 CS
MCLK2 THR1
MDAT2 OVR1
GND RESET
+ 5 V
HCPL-7860/
HCPL-786J
TO
CONTROL
CIRCUIT
C3
0.1 μF
C1
0.1 μF
C2
0.01 μF
R2 39 Ω
R1
D1
5.1 V
HCPL-0872
Power Supplies and Bypassing
The recommended application circuit is shown in Figure
17. A oating power supply (which in many applications
could be the same supply that is used to drive the high-
side power transistor) is regulated to 5 V using a simple
zener diode (D1); the value of resistor R1 should be chosen
to supply sucient current from the existing oating sup-
ply. The voltage from the current sensing resistor or shunt
(Rsense) is applied to the input of the HCPL-7860/HCPL-
786J (U2) through an RC anti-aliasing lter (R2 and C2). And
nally, the output clock and data of the isolated modulator
are connected to the digital interface IC. Although the
application circuit is relatively simple, a few recommenda-
tions should be followed to ensure optimal performance.
The power supply for the isolated modulator is most
often obtained from the same supply used to power the
power transistor gate drive circuit. If a dedicated supply is
required, in many cases it is possible to add an additional
winding on an existing transformer. Otherwise, some sort
of simple isolated supply can be used, such as a line pow-
ered transformer or a high-frequency DC-DC converter.
An inexpensive 78L05 three-terminal regulator can also be
used to reduce the oating supply voltage to 5 V. To help
attenuate high-frequency power supply noise or ripple, a
resistor or inductor can be used in series with the input of
the regulator to form a low-pass lter with the regulator’s
input bypass capacitor.
As shown in Figure 17, 0.1 PF bypass capacitors (C1 and
C3) should be located as close as possible to the input
and output power-supply pins of the isolated modulator
(U2). The bypass capacitors are required because of the
high-speed digital nature of the signals inside the isolated
modulator. A 0.01 PF bypass capacitor (C2) is also recom-
mended at the input due to the switched-capacitor nature
of the input circuit. The input bypass capacitor also forms
part of the anti-aliasing lter, which is recommended to
prevent high-frequency noise from aliasing down to lower
frequencies and interfering with the input signal.
15
Figure 18. Motor Output Horsepower vs. Motor Phase Current and Supply
Voltage.
PC Board Layout
The design of the printed circuit board (PCB) should follow
good layout practices, such as keeping bypass capacitors
close to the supply pins, keeping output signals away
from input signals, the use of ground and power planes,
etc. In addition, the layout of the PCB can also aect the
isolation transient immunity (CMR) of the isolated modu-
lator, due primarily to stray capacitive coupling between
the input and the output circuits. To obtain optimal CMR
performance, the layout of the PC board should minimize
any stray coupling by maintaining the maximum possible
distance between the input and output sides of the circuit
and ensuring that any ground or power plane on the PC
board does not pass directly below or extend much wider
than the body of the isolated modulator.
Shunt Resistors
The current-sensing shunt resistor should have low re-
sistance (to minimize power dissipation), low inductance
(to minimize di/dt induced voltage spikes which could
adversely aect operation), and reasonable tolerance (to
maintain overall circuit accuracy). Choosing a particular
value for the shunt is usually a compromise between
minimizing power dissipation and maximizing accuracy.
Smaller shunt resistances decrease power dissipation,
while larger shunt resistances can improve circuit accuracy
by utilizing the full input range of the isolated modulator.
The rst step in selecting a shunt is determining how much
current the shunt will be sensing. The graph in Figure 18
shows the RMS current in each phase of a three-phase
induction motor as a function of average motor output
power (in horsepower, hp) and motor drive supply volt-
age. The maximum value of the shunt is determined by the
current being measured and the maximum recommended
input voltage of the isolated modulator. The maximum
shunt resistance can be calculated by taking the maximum
recommended input voltage and dividing by the peak cur-
rent that the shunt should see during normal operation.
For example, if a motor will have a maximum RMS current
of 10 A and can experience up to 50% overloads during
normal operation, then the peak current is 21.1 A (= 10 x
1.414 x 1.5). Assuming a maximum input voltage of 200
mV, the maximum value of shunt resistance in this case
would be about 10 m:.
The maximum average power dissipation in the shunt
can also be easily calculated by multiplying the shunt
resistance times the square of the maximum RMS current,
which is about 1 W in the previous example.
If the power dissipation in the shunt is too high, the resis-
tance of the shunt can be decreased below the maximum
value to decrease power dissipation. The minimum value
of the shunt is limited by precision and accuracy require-
ments of the design. As the shunt value is reduced, the
output voltage across the shunt is also reduced, which
means that the oset and noise, which are xed, become
a larger percentage of the signal amplitude. The selected
value of the shunt will fall somewhere between the mini-
mum and maximum values, depending on the particular
requirements of a specic design.
When sensing currents large enough to cause signicant
heating of the shunt, the temperature coecient (tempco)
of the shunt can introduce nonlinearity due to the sig-
nal dependent temperature rise of the shunt. The eect
increases as the shunt-to-ambient thermal resistance
increases. This eect can be minimized either by reducing
the thermal resistance of the shunt or by using a shunt
with a lower tempco. Lowering the thermal resistance can
be accomplished by repositioning the shunt on the PC
board, by using larger PC board traces to carry away more
heat, or by using a heat sink.
15
5
40
15 20 25 30
25
MOTOR PHASE CURRENT - A (rms)
10
30
MOTOR OUTPUT POWER - HORSEPOWER
5350
0
440
380
220
120
10
20
35
16
Table 3. Isotek (Isabellenhütte) Four-Terminal Shunt Summary.
Shunt Resistor
Part Number
Shunt Resistance Tol.
Maximum RMS Cur-
rent
Motor Power Range
120 VAC - 440 VAC
m:% A hp kW
PBV-R050-0.5 50 0.5 3 0.8 - 3 0.6 - 2
PBV-R020-0.5 20 0.5 7 2 - 7 0.6 - 2
PBV-R010-0.5 10 0.5 14 4 - 14 3 - 10
PBV-R005-0.5 5 0.5 25 [28] 7 - 25 [8 - 28] 5 - 19 [6 - 21]
PBV-R002-0.5 2 0.5 39 [71] 11 - 39 [19 - 71] 8 - 29 [14 - 53]
Note: Values in brackets are with a heatsink for the shunt.
For a two-terminal shunt, as the value of shunt resistance
decreases, the resistance of the leads becomes a signi-
cant percentage of the total shunt resistance. This has two
primary eects on shunt accuracy. First, the eective resis-
tance of the shunt can become dependent on factors such
as how long the leads are, how they are bent, how far they
are inserted into the board, and how far solder wicks up
the lead during assembly (these issues will be discussed in
more detail shortly). Second, the leads are typically made
from a material such as copper, which has a much higher
tempco than the material from which the resistive element
itself is made, resulting in a higher tempco for the shunt
overall. Both of these eects are eliminated when a four-
terminal shunt is used. A four-terminal shunt has two ad-
ditional terminals that are Kelvin-connected directly across
the resistive element itself; these two terminals are used
to monitor the voltage across the resistive element while
the other two terminals are used to carry the load current.
Because of the Kelvin connection, any voltage drops across
the leads carrying the load current should have no impact
on the measured voltage.
Several four-terminal shunts from Isotek (Isabellenhütte)
suitable for sensing currents in motor drives up to 71
Arms (71 hp or 53 kW) are shown in Table 3; the maximum
current and motor power range for each of the PBV series
shunts are indicated. For shunt resistances from 50 m:
down to 10 m:, the maximum current is limited by the
input voltage range of the isolated modulator. For the 5
m: and 2 m: shunts, a heat sink may be required due to
the increased power dissipation at higher currents.
When laying out a PC board for the shunts, a couple of
points should be kept in mind. The Kelvin connections
to the shunt should be brought together under the body
of the shunt and then run very close to each other to the
input of the isolated modulator; this minimizes the loop
area of the connection and reduces the possibility of stray
magnetic elds from interfering with the measured signal.
If the shunt is not located on the same PC board as the
isolated modulator circuit, a tightly twisted pair of wires
can accomplish the same thing.
Also, multiple layers of the PC board can be used to in-
crease current carrying capacity. Numerous plated-through
vias should surround each non-Kelvin terminal of the shunt
to help distribute the current between the layers of the PC
board. The PC board should use 2 or 4 oz. copper for the
layers, resulting in a current carrying capacity in excess of
20 A. Making the current carrying traces on the PC board
fairly large can also improve the shunt’s power dissipa-
tion capability by acting as a heat sink. Liberal use of vias
where the load current enters and exits the PC board is
also recommended.
17
Shunt Connections
The recommended method for connecting the isolated
modulator to the shunt resistor is shown in Figure 17. VIN+
(pin 2 of the HPCL-7860/HCPL-786J) is connected to the
positive terminal of the shunt resistor, while VIN- (pin 3) is
shorted to GND1 with the power-supply return path func-
tioning as the sense line to the negative terminal of the
current shunt. This allows a single pair of wires or PC board
traces to connect the isolated modulator circuit to the
shunt resistor. By referencing the input circuit to the nega-
tive side of the sense resistor, any load current induced
noise transients on the shunt are seen as a common-mode
signal and will not interfere with the current-sense signal.
This is important because the large load currents owing
through the motor drive, along with the parasitic induc-
tances inherent in the wiring of the circuit, can generate
both noise spikes and osets that are relatively large com-
pared to the small voltages that are being measured across
the current shunt.
If the same power supply is used both for the gate drive cir-
cuit and for the current sensing circuit, it is very important
that the connection from GND1 of the isolated modulator
to the sense resistor be the only return path for supply cur-
rent to the gate drive power supply in order to eliminate
potential ground loop problems. The only direct connec-
tion between the isolated modulator circuit and the gate
drive circuit should be the positive power supply line.
In some applications, however, supply currents owing
through the power-supply return path may cause oset
or noise problems. In this case, better performance may
be obtained by connecting VIN+ and VIN- directly across
the shunt resistor with two conductors, and connecting
GND1 to the shunt resistor with a third conductor for the
power-supply return path, as shown in Figure 19. When
connected this way, both input pins should be bypassed.
To minimize electromagnetic interference of the sense sig-
nal, all of the conductors (whether two or three are used)
connecting the isolated modulator to the sense resistor
should be either twisted pair wire or closely spaced traces
on a PC board.
The 39 : resistor in series with the input lead (R2) forms
a lowpass anti-aliasing lter with the 0.01 PF input bypass
capacitor (C2) with a 400 kHz bandwidth. The resistor per-
forms another important function as well; it dampens any
ringing which might be present in the circuit formed by
the shunt, the input bypass capacitor, and the inductance
of wires or traces connecting the two. Undamped ringing
of the input circuit near the input sampling frequency can
alias into the baseband producing what might appear to
be noise at the output of the device.
Figure 19. Schematic for Three Conductor Shunt Connection.
+-
MOTOR
HV-
HV+
R
SENSE
FLOATING
POSITIVE
SUPPLY
GATE DRIVE
CIRCUIT
V
DD1
V
IN+
V
IN-
GND1
V
DD2
MCLK
MDAT
GND2
HCPL-7860/
HCPL-786J
C1
0.1 μF
C2a
0.01 μF
R2a 39 Ω
R1
D1
5.1 V
C2b
0.01 μF
R2b 39 Ω
Voltage Sensing
The HCPL-7860/HCPL-786J Isolated Modulator can also
be used to isolate signals with amplitudes larger than its
recommended input range with the use of a resistive volt-
age divider at its input. The only restrictions are that the
impedance of the divider be relatively small (less than 1
k:) so that the input resistance (280 k:) and input bias
current (1 PA) do not aect the accuracy of the measure-
ment. An input bypass capacitor is still required, although
the 39 : series damping resistor is not (the resistance of
the voltage divider provides the same function). The low-
pass lter formed by the divider resistance and the input
bypass capacitor may limit the achievable bandwidth. To
obtain higher bandwidth, the input bypass capacitor (C2)
can be reduced, but it should not be reduced much below
1000 pF to maintain adequate input bypassing of the iso-
lated modulator.
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Avago, Avago Technologies, and the A logo are trademarks of Avago Technologies in the United States and other countries.
Data subject to change. Copyright © 2005-2011 Avago Technologies. All rights reserved. Obsoletes 5989-2166EN
AV02-0409EN - March 28, 2011
