HP HCPL-3700

H
AC/DC to Logic Interface
Optocouplers
Technical Data
HCPL-3700
HCPL-3760
Features
Description
• Standard (HCPL-3700) and
Low Input Current
(HCPL-3760) Versions
• AC or DC Input
• Programmable Sense Voltage
• Hysteresis
• Logic Compatible Output
• Thresholds Guaranteed over
Temperature
• Thresholds Independent of
LED Optical Parameters
• Recognized under UL 1577
and CSA Approved for
Dielectric Withstand Proof
Test Voltage of 2500 Vac, 1
Minute
The HCPL-3700 and HCPL-3760
are voltage/current threshold
detection optocouplers. The
HCPL-3760 is a low-current
version of the HCPL-3700. To
obtain lower current operation,
the HCPL-3760 uses a highefficiency AlGaAs LED which
provides higher light output at
lower drive currents. Both
devices utilize threshold sensing
input buffer ICs which permit
control of threshold levels over a
wide range of input voltages with
a single external resistor.
The input buffer incorporates
several features: hysteresis for
extra noise immunity and
switching immunity, a diode
bridge for easy use with ac input
signals, and internal clamping
Functional Diagram
Applications
• Limit Switch Sensing
• Low Voltage Detector
• 5 V-240 V AC/DC Voltage
Sensing
• Relay Contact Monitor
• Relay Coil Voltage Monitor
• Current Sensing
• Microprocessor Interfacing
AC 1
8
VCC
DC+ 2
7
NC
DC- 3
6
VO
AC 4
5
GND
TRUTH TABLE
(POSITIVE LOGIC)
INPUT OUTPUT
H
L
L
H
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.
1-348
5965-3582E
diodes to protect the buffer and
LED from a wide range of overvoltage and over-current
transients. Because threshold
sensing is done prior to driving
the LED, variations in optical
coupling from the LED to the
detector will have no effect on the
threshold levels.
The buffer IC for the HCPL-3760
was redesigned to permit a lower
input current. The nominal turn
on threshold for the HCPL-3760
is 1.2 mA (ITH +) and 3.7 volts
(VTH +).
The high gain output stage
features an open collector output
providing both TTL compatible
The HCPL-3700's input buffer IC
has a nominal turn on threshold
of 2.5 mA (ITH +) and 3.7 volts
(VTH +).
saturation voltages and CMOS
compatible breakdown voltages.
By combining several unique
functions in a single package, the
user is provided with an ideal
component for industrial control
computer input boards and other
applications where a predetermined input threshold level is
desirable.
Ordering Information
Specify Part Number followed by Option Number (if desired)
Example
HCPL-3700#XXX
300 = Gull Wing Surface Mount Option
500 = Tape/Reel Package Option (1 K min.)
Option data sheets available. Contact your Hewlett-Packard sales representative or authorized distributor for
information.
Schematic
1-349
Package Outline Drawings
Standard DIP Package
9.40 (0.370)
9.90 (0.390)
8
7
6
5
TYPE NUMBER
DATE CODE
HP XXXX
7.36 (0.290)
7.88 (0.310)
YYWW RU
PIN ONE
1
2
3
0.20 (0.008)
0.33 (0.013)
6.10 (0.240)
6.60 (0.260)
5° TYP.
UL
RECOGNITION
4
1.78 (0.070) MAX.
1.19 (0.047) MAX.
4.70 (0.185) MAX.
0.51 (0.020) MIN.
2.92 (0.115) MIN.
1
AC
VCC 8
2
DC+
NC 7
3
DC-
VO 6
4
AC
GND 5
0.65 (0.025) MAX.
0.76 (0.030)
1.40 (0.056)
2.28 (0.090)
2.80 (0.110)
DIMENSIONS IN MILLIMETERS AND (INCHES).
Gull Wing Surface Mount Option 300
PAD LOCATION (FOR REFERENCE ONLY)
9.65 ± 0.25
(0.380 ± 0.010)
8
7
6
1.016 (0.040)
1.194 (0.047)
5
4.826 TYP.
(0.190)
TYPE NUMBER
DATE CODE
HP XXXX
6.350 ± 0.25
(0.250 ± 0.010)
YYWW RU
MOLDED
1
2
3
4
UL
RECOGNITION
1.194 (0.047)
1.778 (0.070)
7.62 ± 0.25
(0.300 ± 0.010)
0.20 (0.008)
0.33 (0.013)
4.19 MAX.
(0.165)
1.080 ± 0.320
(0.043 ± 0.013)
2.540
(0.100)
BSC
0.635 ± 0.130
(0.025 ± 0.005)
0.635 ± 0.25
(0.025 ± 0.010)
DIMENSIONS IN MILLIMETERS (INCHES).
TOLERANCES (UNLESS OTHERWISE SPECIFIED): xx.xx = 0.01
xx.xxx = 0.005
LEAD COPLANARITY
MAXIMUM: 0.102 (0.004)
1-350
0.381 (0.015)
0.635 (0.025)
9.65 ± 0.25
(0.380 ± 0.010)
1.780
(0.070)
MAX.
1.19
(0.047)
MAX.
9.398 (0.370)
9.906 (0.390)
12° NOM.
TEMPERATURE – °C
Maximum Solder Reflow Thermal Profile
260
240
220
200
180
160
140
120
100
∆T = 145°C, 1°C/SEC
∆T = 115°C, 0.3°C/SEC
80
60
40
20
0
∆T = 100°C, 1.5°C/SEC
0
1
2
3
4
5
6
7
8
9
10
11
12
TIME – MINUTES
(NOTE: USE OF NON-CHLORINE ACTIVATED FLUXES IS RECOMMENDED.)
Regulatory Information
The HCPL-3700/60 has been
approved by the following
organizations:
UL
Recognized under UL 1577,
component recognition program,
File E55361.
CSA
Approved under CSA Component
Acceptance Notice #5, File CA
88324.
1-351
Insulation and Safety Related Specifications
Parameter
Symbol Value Units
Min. External Air Gap
L(IO1)
7.1
mm
(External Clearance)
Min. External Tracking
L(IO2)
7.4
mm
Path (External Creepage)
Min. Internal Plastic
0.08 mm
Gap (Internal Clearance)
Tracking Resistance
(Comparative
Tracking Index)
Isolation Group
CTI
200
IIIa
V
Conditions
Measured from input terminals to output terminals,
shortest distance through air
Measured from input terminals to output terminals,
shortest distance path along body
Through insulation distance, conductor to conductor,
usually the direct distance between the photoemitter
and photodetector inside the optocoupler cavity
DIN IEC 112/VDE 0303 PART 1
Material Group (DIN VDE 0110, 1/89, Table 1)
Option 300 – surface mount classification is Class A in accordance with CECC 00802.
Absolute Maximum Ratings (No derating required up to 70°C)
Parameter
Storage Temperature
Operating Temperature
Lead Soldering Cycle
Temperature
Time
Input Current
Average
Surge
Transient
Input Voltage (Pins 2-3)
Input Power Dissipation
Total Package Power Dissipation
Output Power Dissipation
Output Current
Average
Supply Voltage (Pins 8-5)
Output Voltage (Pins 6-5)
Solder Reflow Temperature Profile
Symbol
TS
TA
Min.
-55
-40
IIN
VIN
PIN
PT
PO
IO
VCC
VO
Max.
125
85
260
10
50
140
500
Units
°C
°C
°C
s
mA
V
230
mW
305
mW
210
mW
30
mA
-0.5
20
V
-0.5
20
V
See Package Outline Drawings section
Note
1
2
2, 3
-0.5
4
5
6
7
Recommended Operating Conditions
Parameter
Symbol
Min.
Max.
Units
Supply Voltage
VCC
2
18
V
Operating Temperature
TA
0
70
°C
f
0
4
kHz
Operating Frequency
1-352
Note
8
Electrical Specifications
Over Recommended Temperature TA = 0°C to 70°C, Unless Otherwise Specified.
Parameter
Input Threshold
Current
Sym.
Device
Min. Typ.[9] Max. Units
2.5
3.11
HCPL-3760 0.87
1.2
1.56
HCPL-3700 1.00
1.3
1.62
HCPL-3760 0.43
0.6
0.80
VTH+
3.35
3.7
4.05
V
VIN = V2 - V3; Pins 1 & 4 Open
VCC = 4.5 V; VO = 0.4 V;
IO ≥ 4.2 mA
VTH-
2.01
2.6
2.86
V
VIN = V2 - V3; Pins 1 & 4 Open
VCC = 4.5 V; VO = 2.4 V;
IO ≤ 100 µA
AC
VTH+
(Pins 1, 4)
4.23
4.9
5.50
V
VIN = |V1 - V4|;
Pins 2 & 3 Open
VCC = 4.5 V; VO = 0.4 V;
IO ≥ 4.2 mA
VTH-
2.87
3.7
4.20
V
VIN = |V1 - V4|;
Pins 2 & 3 Open
VCC = 4.5 V; VO = 2.4 V;
IO ≤ 100 µA
ITHInput
DC
Threshold (Pins 2, 3)
Voltage
Hysteresis
IHYS HCPL-3700
1.2
HCPL-3760
0.6
VHYS
Input Clamp Voltage
Input Current
Bridge Diode
Forward Voltage
mA
Conditions
ITH+ HCPL-3700 1.96
IHYS = ITH+ – ITH-
V
VHYS = VTH+ – VTH-
VIHC1
5.4
6.0
6.6
V
VIHC1 = V2 - V3; V3 = GND;
IIN = 10 mA; Pins 1 & 4
Connected to Pin 3
VIHC2
6.1
6.7
7.3
V
VIHC2 = |V1 - V4|;
|IIN| = 10 mA;
Pins 2 & 3 Open
VIHC3
12.0
13.4
V
VIHC3 = V2 - V3; V3 = GND;
IIN = 15 mA; Pins 1 & 4 Open
VILC
-0.76
V
VILC = V2 - V3; V3 = GND;
IIN = -10 mA
IIN
HCPL-3700
3.0
3.7
4.4
HCPL-3760
1.5
1.8
2.2
VD1,2 HCPL-3700
0.59
mA
V
VIN = V2 – V3 = 5.0 V
Pins 1 & 4 Open
HCPL-3760
0.51
IIN = 1.5 mA
0.74
IIN = 3 mA
HCPL-3760
0.71
VOL
0.1
Logic High
Output Current
IOH
Logic Low Supply
Current
ICCL HCPL-3700
HCPL-3760
Logic High Supply
Current
Input Capacitance
2, 3
14
14, 15
2
1
5
IIN = 3 mA
VD3,4 HCPL-3700
Logic Low Output
Voltage
Fig. Note
VIN = VTH-; VCC = 4.5 V;
VO = 2.4 V; IOH ≤ 100 µA
mA
1.2
VIN = VTH+; VCC = 4.5 V;
VO = 0.4 V; IO ≥ 4.2 mA
IIN = 1.5 mA
0.4
V
VCC = 4.5 V; IOL = 4.2 mA
100
µA
VOH = VCC = 18 V
1.2
4
mA
0.7
3
ICCH
0.002
4
CIN
50
V2 – V3 = 5.0 V; VO = Open;
5
14
14
6
VCC = 5.0 V
µA
VCC = 18 V; VO = Open
pF
f = 1 MHz; VIN = 0 V,
Pins 2 & 3, Pins 1 & 4 Open
4
14
1-353
Switching Specifications
TA = 25°C, VCC = 5.0 V, Unless Otherwise Specified.
Parameter
Propagation Delay
Time to Logic Low
at Output
Sym.
Device
Min.
Typ.
HCPL-3700
4.0
HCPL-3760
4.5
HCPL-3700
10.0
HCPL-3760
8.0
HCPL-3700
20
HCPL-3760
14
HCPL-3700
0.3
HCPL-3760
0.4
tPHL
Max.
Units
15.0
µs
Test Conditions
Fig.
RL = 4.7 kΩ, CL = 30 pF
Note
10
7, 10
Propagation Delay
Time to Logic High
at Output
Output Rise Time
(10-90%)
tPLH
40.0
tr
µs
RL = 4.7 kΩ, CL = 30 pF
µs
RL = 4.7 kΩ, CL = 30 pF
11
8
Output Fall Time
(90-10%)
Common Mode
Transient Immunity
at Logic High Output
µs
tf
|CMH|
4000
V/µs
RL = 4.7 kΩ, CL = 30 pF
IIN = 0 mA, RL = 4.7 kΩ,
VO min = 2.0 V, VCM = 1400 V
9, 11
Common Mode
Transient Immunity
at Logic Low Output
IIN = 3.11 mA
HCPL-3700
|CML|
600
V/µs
IIN = 1.56 mA
HCPL-3760
12, 13
RL = 4.7 kΩ,
VO max = 0.8 V,
VCM = 140 V
Package Characteristics
Over Recommended Temperature TA = 0°C to 70°C, Unless Otherwise Specified.
Min. Typ.[9] Max. Units
Parameter
Sym.
Input-Output Momentary
Withstand Voltage*
VISO
Input-Output Resistance
RI-O
1012
Input-Output Capacitance
CI-O
0.6
2500
Conditions
Fig. Note
RH ≤ 50%, t = 1 min;
TA = 25°C
16,
17
Ω
VI-O = 500 Vdc
16
pF
f = 1 MHz; VI-O = 0 Vdc
V rms
*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.”
1-354
Notes:
1. Measured at a point 1.6 mm below seating plane.
2. Current into/out of any single lead.
3. Surge input current duration is 3 ms at 120 Hz pulse repetition rate. Transient input current duration is 10 µs at 120 Hz pulse
repetition rate. Note that maximum input power, PIN, must be observed.
4. Derate linearly above 70°C free-air temperature at a rate of 4.1 mW/°C. Maximum input power dissipation of 230 mW allows an input
IC junction temperature of 125°C at an ambient temperature of TA = 70°C with a typical thermal resistance from junction to ambient
of θJA1 = 240°C/W. Excessive PIN and TJ may result in IC chip degradation.
5. Derate linearly above 70°C free-air temperature at a rate of 5.4 mW/°C.
6. Derate linearly above 70°C free-air temperature at a rate of 3.9 mW/°C. Maximum output power dissipation of 210 mW allows an
output IC junction temperature of 125°C at an ambient temperature of TA = 70°C with a typical thermal resistance from junction to
ambient of θJA0 = 265°C/W.
7. Derate linearly above 70°C free-air temperature at a rate of 0.6 mA/°C.
8. Maximum operating frequency is defined when output waveform Pin 6 obtains only 90% of VCC with RL = 4.7 kΩ, CL = 30 pF using
a 5 V square wave input signal.
9. All typical values are at TA = 25°C, VCC = 5.0 V unless otherwise stated.
10. The tPHL propagation delay is measured from the 2.5 V level of the leading edge of a 5.0 V input pulse (1 µs rise time) to the 1.5 V
level on the leading edge of the output pulse (see Figure 10).
11. The tPLH propagation delay is measured from the 2.5 V level of the trailing edge of a 5.0 V input pulse (1 µs fall time) to the 1.5 V
level on the trailing edge of the output pulse (see Figure 10).
12. Common mode transient immunity in Logic High level is the maximum tolerable (positive) dVCM/dt on the leading edge of the
common mode pulse, VCM, to insure that the output will remain in a Logic High state (i.e., VO > 2.0 V). Common mode transient
immunity in Logic Low level is the maximum tolerable (negative) dVCM/dt on the trailing edge of the common mode pulse signal,
VCM, to insure that the output will remain in a Logic Low state (i.e., VO < 0.8 V). See Figure 11.
13. In applications where dVCM/dt may exceed 50,000 V/µs (such as static discharge), a series resistor, RCC, should be included to
protect the detector IC from destructively high surge currents. The recommended value for RCC is 240 Ω per volt of allowable drop
in VCC (between Pin 8 and VCC) with a minimum value of 240 Ω.
14. Logic low output level at Pin 6 occurs under the conditions of VIN ≥ VTH+ as well as the range of VIN > VTH– once VIN has exceeded
VTH+. Logic high output level at Pin 6 occurs under the conditions of VIN ≤ VTH- as well as the range of VIN < VTH+ once VIN has
decreased below VTH-.
15. AC voltage is instantaneous voltage.
16. Device considered a two terminal device: Pins 1, 2, 3, 4 connected together, and Pins 5, 6, 7, 8 connected together.
17. In accordance with UL 1577, each optocoupler is proof tested by applying an insulation test voltage ≥ 3000 V rms for 1 second
(leakage detection current limit, Ii-o ≤ 5 µA).
Figure 1. Typical Input Characteristics, IIN vs. VIN (AC Voltage is Instantaneous Value).
1-355
DEVICE
TH+
TH–
INPUT
CONNNECTION
ITH
HCPL-3700
HCPL-3760
2.5 mA
1.2 mA
1.3 mA
0.6 mA
PINS 2, 3
OR 1, 4
VTH(dc)
BOTH
3.7 V
2.6 V
PINS 2, 3
VTH(ac)
BOTH
4.9 V
3.7 V
PINS 1, 4
Figure 2. Typical Transfer Characteristics.
HCPL-3760
4.0
3.0
4.0
3.8
2.8
VTH+
3.6
2.6
3.4
2.4
ITH+
3.2
2.2
3.0
2.0
2.8
1.8
VTH-
2.6
1.6
2.4
1.4
ITH-
2.2
1.2
2.0
1.0
1.8
0.8
-40
-20
0
20
40
60
80
TA – TEMPERATURE – °C
Figure 3. Typical DC Threshold Levels vs. Temperature.
1-356
3.8
1.6
1.5
1.4
VTH+
3.6
1.3
ITH+
3.4
1.2
3.2
1.1
3.0
1.0
VTH-
2.8
0.9
2.6
0.8
2.4
0.7
ITH-
2.2
0.6
2.0
0.5
1.8
0.4
-40 -25
0
25
50
TA – TEMPERATURE – °C
75 85
ITH – CURRENT THRESHOLD – mA
4.2
VTH – VOLTAGE THRESHOLD – V
3.2
ITH – CURRENT THRESHOLD – mA
VTH – VOLTAGE THRESHOLD – V
HCPL-3700
4.2
ICCH – HIGH LEVEL SUPPLY CURRENT – µA
100
ICCH
VCC = 18 V
VO = OPEN
IIN = 0 mA
10-1
10-2
ICCH
10-3
10-4
10-5
-40 -25
0
25
50
75 85
TA – TEMPERATURE – °C
Figure 4. Typical High Level Supply Current, ICCH vs.
Temperature.
220
3.8
200
3.6
180
IIN
3.4
160
VIN = 5.0 V
(PINS 2, 3)
VCC = 5.0 V
3.2
3.0
140
120
2.8
100
VOL
2.6
80
VCC = 5.0 V
IOL = 4.2 mA
2.4
60
2.2
40
2.0
20
1.8
0
-40
-20
0
20
40
60
2.1
240
2.0
220
1.9
200
1.8
180
IIN
1.7
160
VIN = 5.0 V
(PINS 2, 3)
VCC = 5.0 V
1.6
1.5
1.4
140
120
100
VOL
1.3
80
VCC = 5.0 V
IOL = 4.2 mA
1.2
60
1.1
40
1.0
20
0.9
0
80
-40 -25
TA – TEMPERATURE – °C
0
25
50
VOL – LOW LEVEL OUTPUT VOLTAGE – mV
4.0
IIN – INPUT CURRENT – mA
HCPL-3760
240
VOL – LOW LEVEL OUTPUT VOLTAGE – mV
IIN – INPUT CURRENT – mA
HCPL-3700
4.2
75 85
TA – TEMPERATURE – °C
Figure 5. Typical Input Current, IIN, and Low Level Output Voltage, VOL, vs. Temperature.
HCPL-3760
ICCL – LOGIC LOW SUPPLY CURRENT – mA
ICCL – LOGIC LOW SUPPLY CURRENT – mA
HCPL-3700
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0
4.0
6.0
8.0
10.0 12.0 14.0 16.0 18.0 20.0
VCC – SUPPLY VOLTAGE – V
3.00
2.50
2.00
1.50
1.00
0.50
0
4.0
6.0
8.0
10.0 12.0 14.0 16.0 18.0 20.0
VCC – SUPPLY VOLTAGE – V
Figure 6. Typical Logic Low Supply Current vs. Supply Voltage.
1-357
HCPL-3760
HCPL-3700
22
tp – PROPAGATION DELAY – µs
24
RL = 4.7 kΩ
CL = 30 pF
VCC = 5.0 V
5.0 V
VIN = 1 ms PULSE WIDTH
f = 100 Hz
tr, tf = 1 µs (10-90%)
20
18
16
22
tp – PROPAGATION DELAY – µs
24
tPLH
14
12
10
8
6
tPHL
4
2
20
18
16
RL = 4.7 kΩ
CL = 30 pF
VCC = 5.0 V
5.0 V
VIN = 1 ms PULSE WIDTH
f = 100 Hz
tr, tf = 1 µs (10-90%)
tPLH
14
12
10
8
6
4
tPHL
2
0
-40
-20
0
20
40
60
0
80
-40 -25
TA – TEMPERATURE – °C
0
25
50
75 85
TA – TEMPERATURE – °C
Figure 7. Typical Propagation Delay vs. Temperature.
HCPL-3700
30
700
500
25
600
20
500
400
300
30
tr
200
20
15
400
tf
10
tr
tf
10
0
-40
-20
0
20
40
60
100
5
0
0
80
CM – COMMON MODE TRANSIENT IMMUNITY – V/ µs
5000
VCC = 5.0 V
IIN = 3.11 mA (3700)
IIN = 1.53 mA (3760)
VOL = 0.8 V
RL = 4.7 kΩ
TA = 25 °C
4000
3000
CML
2000
1000
VCC = 5.0 V
IIN = 0 mA
VOH = 2.0 V
RL = 4.7 kΩ
TA = 25 °C
CMH
500
0
0
400
800
1200
1600
2000
VCM – COMMON MODE TRANSIENT AMPLITUDE – V
Figure 9. Common Mode Transient Immunity
vs. Common Mode Transient Amplitude.
1-358
0
25
50
TA – TEMPERATURE – °C
Figure 8. Typical Rise, Fall Times vs. Temperature.
300
200
100
-40 -25
TA – TEMPERATURE – °C
VIN =
RL = 4.7 kΩ
CL = 30 pF
VCC = 5.0 V
5.0 V
1 ms PULSE WIDTH
f = 100 Hz
tr, tf = 1 µs (10-90%)
75 85
tf – FALL TIME – ns
40
600
tr – RISE TIME – µs
50
tr – RISE TIME – µs
HCPL-3760
RL = 4.7 kΩ
CL = 30 pF
VCC = 5.0 V
5.0 V
VIN = 1 ms PULSE WIDTH
f = 100 Hz
tr, tf = 1 µs (10-90%)
tf – FALL TIME – ns
60
Figure 10. Switching Test Circuit.
Figure 11. Test Circuit for Common Mode Transient Immunity and Typical Waveforms.
VTH+ = 3.7 V
VTH– = 2.6 V
VTH+ = 4.9 V
VTH– = 3.7 V
ITH+ = 2.5 mA
ITH– = 1.3 mA
TA = 25 °C
Figure 12. Typical External Threshold Characteristics, V ± vs. RX.
1-359
Figure 13. External Threshold Voltage Level Selection.
Electrical Considerations
The HCPL-3700/3760 optocouplers have internal temperature
compensated, predictable voltage
and current threshold points
which allow selection of an
external resistor, RX, to determine
larger external threshold voltage
levels. For a desired external
threshold voltage, V± , a corresponding typical value of RX can
be obtained from Figure 12.
Specific calculation of RX can be
obtained from Equation (1).
Specification of both V+ and Vvoltage threshold levels simultaneously can be obtained by the
use of RX and RP as shown in
Figure 13 and determined by
Equations (2) and (3).
RX can provide over-current
transient protection by limiting
input current during a transient
condition. For monitoring contacts of a relay or switch, the
HCPL-3700/3760 in combination
with RX and RP can be used to
allow a specific current to be
conducted through the contacts
for cleaning purposes (wetting
current).
The choice of which input voltage
clamp level to choose depends
upon the application of this
device (see Figure 1). It is recommended that the low clamp
condition be used when possible.
1-360
The low clamp condition in
conjunction with the low input
current feature will ensure
extremely low input power
dissipation.
In applications where dVCM/dt
may be extremely large (such as
static discharge), a series resistor,
RCC, should be connected in
series with VCC and Pin 8 to protect the detector IC from destructively high surge currents. See
Note 13 for determination of RCC.
In addition, it is recommended
that a ceramic disc bypass
capacitor of 0.01 µF be placed
between Pins 8 and 5 to reduce
the effect of power supply noise.
For one specifically selected
external threshold voltage level
V+ or V-, RX can be determined
without use of RP via
V+ - VTH+
(-) (-)
RX =
For two specifically selected
external threshold voltage levels,
V+ and V-, the use of RX and RP
will permit this selection via
equations (2), (3) provided the
following conditions are met. If
the denominator of equation (2)
is positive, then
V+
For interfacing ac signals to TTL
systems, output low pass filtering
can be performed with a pullup
resistor of 1.5 kΩ and 20 µF
capacitor. This application
requires a Schmitt trigger gate to
avoid slow rise time chatter
problems. For ac input applications, a filter capacitor can be
placed across the dc input
terminals for either signal or
transient filtering.
Either ac (Pins 1, 4) or dc
(Pins 2, 3) input can be used to
determine external threshold
levels.
(1)
ITH+
(-)
≥
V-
VTH+
and
VTH-
V+ - VTH+
<
V- - VTH-
ITH+
ITH-
Conversely, if the denominator of
equation (2) is negative, then
V+
≤
V-
RX =
VTH+
VTH-
and
V+ - VTH+
>
V- - VTH-
VTH- (V+) - VTH+ (V-)
ITH+
ITH-
(2)
ITH+ (VTH-) - ITH- (VTH+)
VTH- (V+) - VTH+ (V-)
RP =
(3)
ITH+(V--VTH-)+ITH-(VTH+-V+)