Isolation Amplifier with Short
Circuit and Overload Detection
Technical Data
HCPL-788J
Features
Output Voltage Directly
Compatible with A/D
Converters (0 V to V
REF
)
Fast (3
s) Short Circuit
Detection with Transient
Fault Rejection
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
FAULT
ABSVAL
V
OUT
V
REF
V
IN+
V
IN-
R
SENSE1
SHORT CIRCUIT FAULT
ISOLATION BOUNDARY
A/D
CONVERTER
MICRO
CONTROLLER
HCPL-788J
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
FAULT
ABSVAL
V
OUT
V
REF
V
IN+
V
IN-
R
SENSE2
ISOLATION BOUNDARY
HCPL-788J
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
FAULT
ABSVAL
V
OUT
V
REF
V
IN+
V
IN-
R
SENSE3
ISOLATION BOUNDARY
HCPL-788J
M
+5 V
OVERLOAD
FAULT
+
+
3 PHASE ABSOLUTE
VALUE OUTPUT
V
REF
V
TH
3 PHASE
MOTOR
Low Cost Three Phase Current Sensing with Short Circuit and Overload Detection
Hewlett-Packard's Isolation Amplifier with Short Circuit and Overload Detection makes motor phase
current sensing compact, affordable and easy-to-implement while satisfying worldwide safety and
regulatory requirements.
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.
Absolute Value Signal Out-
put for Overload Detection
1
V/
C Offset Change vs.
Temperature
SO-16 Package
-40
C to +85
C Operating
Temperature Range
25 kV/
s Isolation Transient
Immunity
Regulatory Approvals
(Pending): UL, CSA, VDE
0884 (891 Vpeak Working
Voltage)
2
Symbol
Description
GND
2
Ground input.
V
DD2
Supply voltage input (4.5 V to 5.5 V).
FAULT
Short circuit fault output. FAULT changes
from a high to low output voltage within
6
s after V
IN
exceeds the FAULT Detec-
tion Threshold. FAULT is an open drain
output which allows outputs from all the
HCPL-788Js in a circuit to be connected
together ("wired-OR") forming a single
fault signal for interfacing directly to the
micro-controller.
ABSVAL
Absolute value of V
OUT
output. ABSVAL
is 0 V when V
IN
=0 and increases toward
V
REF
as V
IN
approaches +256 mV or
-256 mV. ABSVAL is "wired-OR" able
and is used for detecting overloads.
V
OUT
Voltage output. Swings from 0 to V
REF
.
The nominal gain is V
REF
/504 mV.
V
REF
Reference voltage input (4.0 V to V
DD2
).
This voltage establishes the full scale
output ranges and gains of V
OUT
and
ABSVAL.
V
DD2
Supply voltage input (4.5 V to 5.5 V).
GND
2
Ground input.
Pin Descriptions
Symbol
Description
V
IN+
Positive input voltage (
200 mV
recommended).
V
IN-
Negative input voltage (normally
connected to GND
1
).
C
H
Internal Bias Node. Connections to or
between C
H
and C
L
other than the re-
quired 0.1
F capacitor shown, are not
recommended.
C
L
V
DD1
Supply voltage input (4.5 V to 5.5 V).
V
LED+
LED anode. This pin must be left uncon-
nected for guaranteed data sheet perfor-
mance. (For optical coupling testing only.)
V
DD1
Supply voltage input (4.5 V to 5.5 V).
GND
1
Ground input.
Description
The HCPL-788J isolation amplifier
is designed for current sensing in
electronic motor drives. In a
typical implementation, motor
currents flow through an external
resistor and the resulting analog
voltage drop is sensed by the
HCPL-788J. A larger analog
output voltage is created on the
other side of the HCPL-788J's
optical isolation barrier. The
output voltage is proportional
to the motor current and can be
connected directly to a single-
supply A/D converter. A digital
over-range output (FAULT) and
an analog rectified output
(ABSVAL) are also provided. The
wire OR-able over-range output
(FAULT) is useful for quick
detection of short circuit con-
Figure 1. Current Sensing Circuit.
ditions on any of the motor
phases. The wire-OR-able rectified
output (ABSVAL), simplifies
measurement of motor load since
it performs polyphase rectification.
Since the common-mode voltage
swings several hundred volts in
tens of nanoseconds in modern
electronic motor drives, the
HCPL-788J was designed to
ignore very high common-mode
transient slew rates (10 kV/
s).
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
GND
2
V
DD2
FAULT
ABSVAL
V
OUT
V
REF
V
DD2
GND
2
V
IN+
V
IN-
C
H
C
L
V
DD1
V
LED+
V
DD1
GND
1
R
SHUNT
0.02
ISOLATED +5 V
4.7 k
39
.01 F
0.1 F
0.1 F
ISOLATION BOUNDARY
INPUT
CURRENT
+5 V
A/D
V
REF
GND
C
TO OTHER
PHASE
OUTPUTS
+
0.1 F
HCPL-788J
3
Ordering Information
Specify Part Number followed by Option Number (if desired).
Example
HCPL-788J#XXX
No Option = 16-Lead, Surface Mt. package, 45 per tube.
500 = Tape and Reel Packaging Option, 850 per reel.
Option Data sheets available. Contact Hewlett-Packard sales representative, authorized distributor, or visit
our Web site at www.hp.com/go/isolator.
Package Outline Drawings
16-Lead Surface Mount
dimensions in inches
(millimeters)
Package Characteristics
Parameter Symbol
Min.
Typ.
Max.
Units
Test Conditions
Fig.
Notes
Input-Output Momentary V
ISO
3750
Vrms
RH < 50%, t = 1
1,2,3
Withstand Voltage
min., T
A
= 25
C
Resistance (Input-Output) R
I-O
>10
9
V
I-O
= 500 V
DC
3
Capacitance (Input-Output) C
I-O
1.3
pF
f = 1 MHz
Input IC Junction-to-Case
jci
120
C/W
T
A
= 85
C
Thermal Resistance
Output IC Junction-to-Case
jco
100
Thermal Resistance
Note: Initial and continued
variation in the color of the
HCPL-788J's white mold
compound is normal and does
not affect device performance
or reliability.
240
T = 115C, 0.3C/SEC
0
T = 100C, 1.5C/SEC
T = 145C, 1C/SEC
TIME MINUTES
TEMPERATURE C
220
200
180
160
140
120
100
80
60
40
20
0
260
1
2
3
4
5
6
7
8
9
10
11
12
(NOTE: USE OF NON-CHLORINE ACTIVATED FLUXES IS RECOMMENDED.)
Maximum Solder Reflow Temperature Profile
9
0.295 0.010
(7.493 0.254)
10
11
12
13
14
15
16
8
7
6
5
4
3
2
1
0.018
(0.457)
0.138 0.005
(3.505 0.127)
9
0.406 0.10
(10.312 0.254)
0.408 0.010
(10.160 0.254)
0.025 MIN.
0.008 0.003
(0.203 0.076)
STANDOFF
0.345 0.010
(8.986 0.254)
08
0.018
(0.457)
0.050
(1.270)
ALL LEADS
TO BE
COPLANAR
0.002
HP 788J
YYWW
TYPE NUMBER
DATE CODE
4
Regulatory Information
The HCPL-788J is pending approval by the following organizations:
Figure 2. Dependence of Safety-
Limiting Values on Temperature.
VDE 0884 Insulation Characteristics*
Description
Symbol
Characteristic
Unit
Installation classification per DIN VDE 0110/1.89, Table 1
for rated mains voltage
300 V
rms
I-IV
for rated mains voltage
300 V
rms
I-III
for rated mains voltage
600 V
rms
I-II
Climatic Classification
55/85/21
Pollution Degree (DIN VDE 0110/1.89)
2
Maximum Working Insulation Voltage
V
IORM
891
V
PEAK
Input to Output Test Voltage, Method b**
V
IORM
x 1.875 = V
PR
, 100% Production Test with
V
PR
1670
V
PEAK
tm = 1 sec, Partial discharge < 5 pC
Input to Output Test Voltage, Method a**
V
IORM
x 1.5 = V
PR
, Type and Sample Test, t
m
= 60 sec,
V
PR
1336
V
PEAK
Partial discharge < 5 pC
Highest Allowable Overvoltage
V
IOTM
6000
V
PEAK
(Transient Overvoltage t
ini
= 10 sec)
Safety-limiting values -- maximum values allowed in the
event of a failure, also see Figure 2.
Case Temperature
T
S
175
C
Input Power
P
S1, INPUT
400
mW
Output Power
P
S1, OUTPUT
600
mW
Insulation Resistance at T
SI
, V
IO
= 500 V
R
S
>10
9
* Isolation characteristics are guaranteed only within the safety maximum ratings which must be ensured by protective circuits within
the application. Surface Mount Classification is class A in accordance with CECC00802.
** Refer to the optocoupler section of the isolation and Control Components Designer's Catalog, under Product Safety Regulations
section, (VDE-0884) for a detailed description of Method a and Method b partial discharge test profiles.
VDE
Approved under VDE0884/06.92
with V
IORM
= 891 Vpeak.
UL
Recognized under UL 1577, com-
ponent recognition program, File
E55361.
CSA
Approved under CSA Component
Acceptance Notice #5, File CA
88324.
P
s
POWER mW
0
0
TS CASE TEMPERATURE C
200
25
800
50
75 100
200
150 175
Psi OUTPUT
Psi INPUT
125
400
600
5
Insulation and Safety Related Specifications
Parameter
Symbol
Min.
Max.
Conditions
Minimum External Air Gap
L(101)
8.3
mm
Measured from input terminals to output
(Clearance)
terminals, shortest distance through air.
Minimum External Tracking
L(102)
8.3
mm
Measured from input terminals to output
(Creepage)
terminals, shortest distance path along body.
Minimum Internal Plastic Gap
0.5
mm
Through insulation distance conductor to
(Internal Clearance)
conductor, usually the straight line distance
thickness between the emitter and detector.
Tracking Resistance
CTI
>175
Volts
DIN IEC 112/VDE 0303 Part 1
(Comparative Tracking Index)
Isolation Group
IIIa
Material Group (DIN VDE 0110, 1/89, Table 1)
Recommended Operating Conditions
Parameter
Symbol
Min.
Max.
Units
Note
Ambient Operating Temperature
T
A
-40
85
C
Supply Voltages
V
DD1
, V
DD2
4.5
5.5
V
Input Voltage (accurate and linear)
V
IN+
, V
IN-
-200
200
mV
Input Voltage (functional)
V
IN+
, V
IN-
-2
2
V
Reference Input Voltage
V
REF
4.0
V
DD2
FAULT Output Current
I
FAULT
4
mA
Absolute Maximum Ratings
Parameter
Symbol
Min.
Max.
Units
Note
Storage Temperature
T
S
-55
125
C
Operating Temperature
T
A
-40
100
Supply Voltages
V
DD1
, V
DD2
0.0
5.5
V
4
Steady-State Input Voltage
V
IN+
, V
IN-
-2.0
V
DD1
+ 0.5
2 Second Transient Input Voltage
-6.0
Output Voltage
V
OUT
-0.5
V
DD2
+ 0.5
Absolute Value Output Voltage
ABSVAL
-0.5
V
DD2
+ 0.5
Reference Input Voltage
V
REF
0
V
DD2
+ 0.5 V
5
Reference Input Current
I
REF
20
mA
Output Current
I
VOUT
20
Absolute Value Current
I
ABSVAL
20
FAULT Output Current
I
FAULT
20
Input IC Power Dissipation
P
I
200
mW
Output IC Power Dissipation
P
O
200
Solder Reflow Temperature Profile
See Package Outline Drawings section
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