ACPL-W70L-000E and ACPL-K73L-000E
Single-Channel and Dual-Channel High-Speed
15-MBd CMOS Optocoupler with Glitch-Free
Power-Up Feature
Data Sheet
Description
Features
The ACPL-W70L (single-channel) and ACPL-K73L
(dual-channel) are 15-MBd CMOS optocouplers in SSOIC-6 and
SSOIC-8 package respectively. The optocouplers utilize the
latest CMOS IC technology to achieve outstanding
performance with very low power consumption. Basic building
blocks of ACPL-W70L and ACPL-K73L are high-speed LEDs and
CMOS detector ICs. Each detector incorporates an integrated
photodiode, a high-speed transimpedance amplifier, and a
voltage comparator with an output driver.
Features
Component Image
ACPL-W70L
6 VDD
Anode 1
+3.3V and 5V CMOS compatibility
25 ns max pulse width distortion
55 ns max propagation delay
40 ns max propagation delay skew
High speed: 15 MBd min
10 kV/μs minimum common-mode rejection
–40 to +105°C temperature range
Glitch-free power-up feature
Safety and regulatory approvals:
— UL recognized: 5000 V rms for 1 min. per UL 1577
— CSA component acceptance Notice #5
— IEC/EN/DIN EN 60747-5-5 approval for Reinforced
Insulation
5 Vo
NC* 2
Applications
Cathode 3
4 GND
SHIELD
ACPL-K73L
Anode1 1
8 VDD
7 Vo 1
Cathode1 2
Cathode2 3
Digital field bus isolation:
— CANBus, RS485, USB
Multiplexed data transmission
Computer peripheral interface
Microprocessor system interface
DC/DC converter
6 Vo 2
Anode2 4
5 GND
SHIELD
Truth Table
LED
ON
OFF
VO, Output
CAUTION
H
L
A 0.1-μF bypass capacitor must be connected between pins VDD and GND.
Broadcom
-1-
It is advised that normal static precautions be
taken in handling and assembly of this
component to prevent damage and/or
degradation that may be induced by ESD.
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Ordering Information
Ordering Information
ACPL-W70L and ACPL-K73L are UL Recognized with 5000 Vrms for 1 minute per UL1577.
Part Number
Option
RoHS
Compliant
Package
Surface Mount
ACPL-W70L
-000E
SSO-6
X
-500E
X
-060E
X
-560E
ACPL-K73L
-000E
X
SSO-8
Tape & Reel
X
X
X
-500E
X
-060E
X
-560E
X
X
X
UL 5000 Vrms/ 1
Minute Rating
IEC/EN/DIN EN
60747-5-5
Quantity
X
100 per tube
X
1000 per reel
X
X
100 per tube
X
X
1000 per reel
X
80 per tube
X
1000 per reel
X
X
80 per tube
X
X
1000 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:
ACPL-W70L-500E to order product of stretched SO-6 package in Tape and Reel packaging in RoHS compliant.
Option data sheets are available. Contact your Broadcom sales representative or authorized distributor for information.
Broadcom
-2-
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Package Dimensions
Package Dimensions
ACPL-W70L (Stretched SO-6 Package)
LAND PATTERN RECOMMENDATION
12.65 (0.498)
1.27 (0.050) BSG
0.381 0.127
(0.015 0.005)
1
6
2
5
3
4
+0.127
6.807 0
(0.268 +0.005)
- 0.000
0.45 (0.018)
7
45
+0.254
4.580 0
+0.010
(0.180
)
- 0.000
0.76 (0.030)
1.91 (0.075)
1.590 0.127
(0.063 0.005)
7
3.180 0.127
(0.125 0.005)
0.20 0.10
(0.008 0.004)
0.750 0.250
(0.0295 0.010)
DIMENSIONS IN MILLIMETERS (INCHES).
LEAD COPLANARITY = 0.1 mm (0.004 INCHES).
11.50 0.250
(0.453 0.010)
ACPL-K73L (Stretched S0-8 Package)
LAND PATTERN RECOMMENDATION
12.650 (0.5)
1.270 (0.050) BSG
0.381 0.13
(0.015 0.005)
0.450 (0.018)
1
8
2
7
3
6
4
5
7
45
1.905 (0.1)
1.590 0.127
(0.063 0.005)
7
3.180 0.127
(0.125 0.005)
0.200 0.100
(0.008 0.004)
0.750 0.250
(0.0295 0.010)
+0.25
5.850 0
+0.010
(0.230
)
- 0.000
6.807 0.127
(0.268 0.005)
11.5 0.250
(0.453 0.010)
DIMENSIONS IN MILLIMETERS (INCHES).
LEAD COPLANARITY = 0.1 mm (0.004 INCHES).
Broadcom
-3-
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Solder Reflow Profile
Solder Reflow Profile
The recommended reflow soldering conditions are per JEDEC Standard J-STD-020 (latest revision). Non-halide flux should be used.
Regulatory Information
The ACPL-W70L and ACPL-K73L are approved by the following organizations:
UL
Recognized under UL 1577, component recognition program, File E55361.
CSA
Approval under CSA Component Acceptance Notice #5, File CA 88324.
IEC/EN/DIN EN 60747-5-5
Approved.
Insulation and Safety Related Specifications
Parameter
Symbol
Value
Unit
Minimum External Air Gap
(Clearance)
L(101)
8.0
mm
Measured from input terminals to output terminals, shortest
distance through air.
Minimum External Tracking
(Creepage)
L(102)
8.0
mm
Measured from input terminals to output terminals, shortest
distance path along body.
0.08
mm
Insulation thickness between emitter and detector; also known as
distance through insulation.
>175
V
Minimum Internal Plastic Gap
(Internal Clearance)
Tracking Resistance
(Comparative Tracking Index)
Isolation Group
CTI
IIIa
Conditions
DIN IEC 112/VDE 0303 Part 1.
Material Group (DIN VDE 0110, 1/89, Table 1.)
All Avago Technologies data sheets report the creepage and clearance inherent to the optocoupler component itself. These
dimensions are needed as a starting point for the equipment designer when determining the circuit insulation requirements.
However, once mounted on a printed circuit board, minimum creepage and clearance requirements must be met as specified for
individual equipment standards. For creepage, the shortest distance path along the surface of a printed circuit board between the
solder fillets of the input and output leads must be considered.
There are recommended techniques such as grooves and ribs that can be used on a printed circuit board to achieve desired
creepage and clearances. Creepage and clearance distances also change depending on factors such as pollution degree and
insulation level.
Broadcom
-4-
IEC/EN/DIN EN 60747-5-5 Insulation Characteristicsa
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
IEC/EN/DIN EN 60747-5-5 Insulation Characteristicsa
Descriptiona
Symbol
Option 060
Unit
Installation Classification per DIN VDE 0110/1.89, Table 1
for rated mains voltage ≤ 150 Vrmsa
I – IV
for rated mains voltage ≤ 300 Vrms
I – IV
for rated mains voltage ≤ 450 Vrms
I – IV
for rated mains voltage ≤ 600 Vrms
I – IV
for rated mains voltage ≤ 1000 Vrms
I – III
55/105/21
Climatic Classification
2
Pollution Degree (DIN VDE 0110/1.89)
Maximum Working Insulation Voltage
Input to Output Test Voltage, Method bb
VIORM
1140
Vpeak
VPR
2137
Vpeak
VPR
1824
Vpeak
VIOTM
8000
Vpeak
TS
175
°C
IS, INPUT
230
mA
PS, OUTPUT
600
mW
RIO
>109
Ω
VIORM x 1.875 = VPR, 100% Production Test with tm = 1 sec, Partial Discharge < 5 pC
Input to Output Test Voltage, Method ab
VIORM x 1.6 = VPR, Type and Sample Test, tm = 10 sec, Partial Discharge < 5 pC
Highest Allowable Overvoltage (Transient Overvoltage tini = 60 sec)
Safety-limiting Values – Maximum Values Allowed in the Event of a Failure
Case Temperature
Input Currentb
Output Powerb
Insulation Resistance at TS, VIO = 500V
a.
Isolation characteristics are guaranteed only within the safety maximum ratings, which must be ensured by protective circuits in application. Surface mount
classification is class A in accordance with CECCOO802.
b.
Refer to the optocoupler section of the Isolation and Control Components Designer’s Catalog, under Product Safety Regulations section IEC/EN/DIN EN
60747-5-5, for a detailed description of Method a and Method b partial discharge test profiles.
Note: These optocouplers are suitable for safe electrical isolation only within the safety limit data. Maintenance of the safety data must be ensured by means of
protective circuits. The surface mount classification is Class A in accordance with CECC 00802.
Broadcom
-5-
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Absolute Maximum Ratings
Absolute Maximum Ratings
Parameter
Symbol
Min
Max
Unit
Storage Temperature
TS
–55
+125
°C
Ambient Operating Temperature
TA
–40
+105
°C
Supply Voltage
VDD
0
6
V
Output Voltage
VO
–0.5
VDD + 0.5
V
Average Forward Input Current
IF
—
10
mA
Average Output Current
Io
—
10
mA
Lead Solder Temperature
260°C for 10 sec, 1.6 mm below seating plane
Solder Reflow Temperature Profile
See Solder Reflow Profile section.
Recommended Operating Conditions
Parameter
Symbol
Min
Max
Unit
TA
–40
+105
°C
VDD
4.5
5.5
V
Ambient Operating Temperature
Supply Voltages
3.0
3.6
V
Input Current (ON)
IF
4
8
mA
Supply Voltage Slew Ratea
SR
0.5
500
V/ms
a.
Slew rate of supply voltage ramping is recommended to ensure no glitch more than 1V to appear at the output pin.
Electrical Specifications
Over recommended temperature (TA = –40°C to +105°C), 3.0V ≤ VDD ≤ 3.6V and 4.5V ≤ VDD ≤ 5.5V.
All typical specifications are at TA = +25°C, VDD = +3.3V.
Parameter
Input Forward Voltage
Symbol
Part
Number
VF
Min
Typ
Max
Unit
Test Conditions
1.2
1.5
1.85
V
IF = 6 mA
Input Reverse Breakdown Voltage
BVR
5.0
—
—
V
IR = 10 μA
Logic High Output Voltage
VOH
VDD – 1
VDD – 0.3
—
V
IF = 6 mA, IO = –4 mA, VDD = 3.3V
VDD – 1
VDD – 0.2
—
V
IF = 6 mA, IO = –4 mA, VDD = 5V
—
0.2
0.8
V
IF = 0 mA, IO = 4 mA, VDD = 3.3V
—
0.2
0.8
V
IF = 0 mA, IO = 4 mA, VDD = 5V
—
1
3
mA
IOL = 20 μA
ACPL-W70L
—
4.1
6.5
mA
IF = 0 mA
ACPL-K73L
—
8.2
13
mA
IF = 0 mA
ACPL-W70L
—
3.8
6
mA
IF = 6 mA
ACPL-K73L
—
7.6
12
mA
IF = 6 mA
Logic Low Output Voltage
VOL
Input Threshold Current
ITH
Logic Low Output Supply Current
IDDL
Logic Low Output Supply Current
IDDH
Broadcom
-6-
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Switching Specifications
Switching Specifications
Over recommended temperature (TA = –40°C to +105°C), 3.0V ≤ VDD ≤ 3.6V and 4.5V ≤ VDD ≤ 5.5V.
All typical specifications are at TA = +25°C, VDD = +3.3V.
Parameter
Symbol
Min
Typ
Max
Unit
tPHL
—
23
55
ns
Propagation Delay Time to Logic Low Outputa
Test Conditions
IF = 6 mA, CL= 15 pF
CMOS Signal Levels
tPLH
Propagation Delay Time to Logic High Outputa
—
27
55
ns
IF = 6 mA, CL= 15 pF
CMOS Signal Levels
tPW
66.7
—
—
ns
|PWD|
0
4
25
ns
Pulse Width
Pulse Width Distortionb
—
IF = 6 mA, CL = 15 pF
CMOS Signal Levels
tPSK
Propagation Delay Skewc
—
—
40
ns
IF = 6 mA, CL = 15 pF
CMOS Signal Levels
Output Rise Time (10% to 90%)
tR
—
3.5
—
ns
IF = 6 mA, CL = 15 pF
CMOS Signal Levels
Output Fall Time (90% to 10%)
—
tF
3.5
—
ns
IF = 0 mA, CL = 15 pF
CMOS Signal Levels
Common-Mode Transient Immunity at Logic High Outputd
|CMH|
10
15
—
kV/μs VCM = 1000V, TA = 25°C, IF = 6 mA
Common-Mode Transient Immunity at Logic Low Outpute
|CML|
10
15
—
kV/μs VCM = 1000V, TA = 25°C, IF = 0 mA
a.
tPHL propagation delay is measured from the 50% level on the rising edge of the input pulse to the 50% level on the falling edge of the VO signal.
tPLH propagation delay is measured from the 50% level on the falling edge of the input pulse to the 50% level on the rising edge of the VO signal.
b.
PWD is defined as |tPHL – tPLH|.
c.
tPSK is equal to the magnitude of the worst-case difference in tPHL and/or tPLH that is seen between units at any given temperature within the recommended
operating conditions.
d.
CMH is the maximum tolerable rate of rise of the common-mode voltage to assure that the output remains in a high logic state.
e.
CML is the maximum tolerable rate of fall of the common-mode voltage to assure that the output remains in a low logic state.
Package Characteristics
All typical at TA = 25°C.
Parameter
Input-Output Insulation
Symbol
Min
Typ
Max
Unit
II-O
—
—
1.0
μA
Test Conditions
45% RH, t = 5 sec
VI-O = 3 kV dc,
TA = 25°C
Input-Output Momentary Withstand Voltage
VISO
5000
—
—
Vrms
Input-Output Resistance
R I-O
—
10 12
—
Ω
V I-O = 500V dc
Input-Output Capacitance
C I-O
—
0.6
—
pF
f = 1 MHz, TA = 25°C
Broadcom
-7-
RH ≤ 50%, t = 1 min.,
TA = 25°C
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Package Characteristics
Figure 1 Typical Input Diode Forward Characteristic
Figure 2 Typical Input Threshold Current vs. Temperature
10
1.600
Ith - INPUT THRESHOLD CURRENT-mA
IF - FORWARD CURRENT-mA
IF
TA=25°C
1
VF
0.1
0.01
1.2
1.3
1.4
1.5
VF - FORWARD VOLTAGE-V
IDDL -LOGIC LOW OUTPUT SUPPLY CURRENT-mA
6
4
VDD=5V
VDD=3.3V
0
0
20
40
60
T A -TEMPERATURE- oC
80
100
tp – PROPAGATION DELAY; PWD-Pulse Width
h
Distortion – ns
0.200
-20
0
20
40
60
T A-TEMPERATURE- oC
80
100
120
12
10
8
6
4
VDD=5V
VDD=3.3V
2
0
-20
0
20
40
60
T A-TEMPERATURE- oC
80
100
Figure 6 Typical Switching Speed vs. Pulse Input Current at 3.3V
Supply Voltage
35
35
t PLH CH2
t PHL CH1
25
20
15
5V
3.3V
0.400
-40
Figure 5 Typical Switching Speed vs. Pulse Input Current at 5V
Supply Voltage
30
I OL =20uA
0.600
tp – PROPAGATION DELAY; PWD-Pulse
Width Distortion – ns
I DDH -LOGIC HIGH OUTPUT SUPPLY CURRENT-mA
8
-20
0.800
Figure 4 Typical Logic Low Output Supply Current vs. Temperature
for Dual Channel (ACPL-K73L)
10
-40
1.000
-40
12
2
1.200
0.000
1.6
Figure 3 Typical Logic High Output Supply Current vs.
Temperature for Dual Channel (ACPL-K73L)
1.400
t PHL CH2
10
5 VDD=5V
TA=25°C
0
5
4
t PLH CH1
|PWD| CH1
|PWD| CH2
6
7
8
IF – PULSE INPUT CURRENT – mA
9
10
Broadcom
-8-
t PLH CH2
30
t PHL CH1
25
20
15
t PLH CH1
t PHLCH2
10
|PWD| CH1
|PWD| CH2
5 VDD=5V
TA=25°C
0
5
4
6
7
8
IF – PULSE INPUT CURRENT – mA
9
10
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Bypassing and PC Board Layout
Propagation delay skew, tPSK, is an important parameter to
consider in parallel data applications where synchronization of
signals on parallel data lines is a concern. If the parallel data is
being sent through a group of optocouplers, differences in
propagation delays cause the data to arrive at the outputs of
the optocouplers at different times. If this difference in
propagation delays is large enough, it determines the
maximum rate at which parallel data can be sent through the
optocouplers.
Figure 7 Typical VF vs. Temperature
1.8
V F FORWARD VOLTAGE-V
1.7
1.6
1.5
1.4
1.3
Propagation delay skew is defined as the difference between
the minimum and maximum propagation delays, either tPLH or
tPHL, for any given group of optocouplers that are operating
under the same conditions (i.e., the same supply voltage,
output load, and operating temperature). As illustrated in
Figure 10, if the inputs of a group of optocouplers are switched
either ON or OFF at the same time, tPSK is the difference
between the shortest propagation delay, either tPHL or tPHL,
and the longest propagation delay, either tPHL or tPHL. As
mentioned earlier, tPSK can determine the maximum parallel
data transmission rate.
1.2
1.1
1
-40
-20
0
20
40
60
T A-TEMPERATURE- o C
80
100
Bypassing and PC Board Layout
The ACPL-W70L and ACPL-K73L optocouplers are extremely
easy to use. ACPL-W70L and ACPL-K73L provide CMOS logic
output due to the high-speed CMOS IC technology used.
The external components required for proper operation are the
input limiting resistor and the output bypass capacitor.
Capacitor values should be between 0.01 μF and 0.1 μF.
For each capacitor, the total lead length between both ends of
the capacitor and the power-supply pins should not exceed
20 mm.
Propagation Delay, Pulse-Width
Distortion, and Propagation Delay Skew
Propagation delay is a figure of merit that describes how
quickly a logic signal propagates through a system. The
propagation delay from low to high (tPLH) is the amount of time
required for an input signal to propagate to the output,
causing the output to change from low to high.
Similarly, the propagation delay from high to low (tPHL) is the
amount of time required for the input signal to propagate to
the output, causing the output to change from high to low (see
Figure 9).
Pulse-width distortion (PWD) results when tPLH and tPHL differ
in value. PWD is defined as the difference between tPLH and
tPHL. This parameter determines the maximum data rate
capability of a transmission system. PWD can be expressed in
percent by dividing the PWD (in ns) by the minimum pulse
width (in ns) being transmitted. Typically, PWD on the order of
20% to 30% of the minimum pulse width is tolerable; the exact
figure depends on the particular application (RS232, RS422,
T-1, etc.).
Figure 10 is the timing diagram of a typical parallel data
application with both the clock and the data lines being sent
through optocouplers. The figure shows data and clock signals
at the inputs and outputs of the optocouplers. To obtain the
maximum data transmission rate, both edges of the clock
signal are being used to clock the data; if only one edge were
used, the clock signal would need to be twice as fast.
Propagation delay skew represents the uncertainty of where an
edge might be after being sent through an optocoupler.
Figure 10 shows that there is uncertainty in both the data and
the clock lines. It is important that these two areas of
uncertainty not overlap; otherwise, the clock signal might
arrive before all of the data outputs have settled, or some of the
data outputs might start to change before the clock signal has
arrived.
With these considerations, the absolute minimum pulse width
that can be sent through optocouplers in a parallel application
is twice tPSK. A cautious design should use a slightly longer
pulse width to ensure that any additional uncertainty in the
rest of the circuit does not cause a problem.
The tPSK specified optocouplers offer the advantages of
guaranteed specifications for propagation delays, pulse-width
distortion, and propagation delay skew over the
recommended temperature and power supply ranges.
Broadcom
-9-
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Propagation Delay, Pulse-Width Distortion, and Propagation Delay Skew
Figure 8 Recommended Printed Circuit Board Layout
1
IF
3
4
GND 1
2
GND 1
3
IF2
4
Vo
GND2
ACPL-W70L
ACPL-K73L
Figure 9 Propagation Delay Skew Waveform
50%
2.5 V,
CMOS
VO
tPSK
VI
50%
2.5 V,
CMOS
VO
Figure 10 Parallel Data Transmission Example
DATA
INPUTS
CLOCK
DATA
OUTPUTS
7
VO1
6
VO2
5
C=0.01μF to 0.1μF
VI
VDD
8
XXX
YWW
GND1
5
1
C
C
XXX
YWW
2
IF1
V DD
6
tPSK
CLOCK
tPSK
Broadcom
- 10 -
GND 2
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Powering Sequence
Powering Sequence
Figure 12 Improvement of tp and PWD with Added 100-pF Peaking
Capacitor in Parallel of Input Limiting Resistor
VDD must achieve a minimum level of 3V before powering up
the output connecting component.
35
t PLH
30
Input Limiting Resistor
The ACPL-W70L and ACPL-K73L are direct current driven
(Figure 8), and thus eliminate the need for input power supply.
To limit the amount of current flowing through the LED, it is
recommended that a 530Ω resistor is connected in series with
anode of LED (i.e., Pin 1 for ACPL-W70L, Pin 1 and P4 for
ACPL-K73L) at 5V input signal. At 3.3V input signal, it is
recommended to connect a 250Ω resistor in series with anode
of LED. The recommended limiting resistors is based on the
assumption that the driver output impedance is 50Ω (as shown
in Figure 11).
Figure 11 Connection of Peaking Capacitor (Cpeak) in Parallel of
the Input Limiting Resistor (Rllimit) to Improve Speed Performance
t PHL
25
t PHL
20
15
t PLH
10
|PWD|
5
0
-40
-20
0
+
Vi
C peak
0.1μF
-
GND1
SHIELD
VDD2
25
VO
20
60
80
100
tPHL
tPLH
t PHL
15
t PLH
10
GND 2
40
40
30
Rlimit
20
(i) VDD2 = 5V, Cpeak = 100 pF, Rlimit = 530Ω
35
R drv =
50:
With peaking cap
Without peaking cap
5
With peaking cap
Without peaking cap
|PWD|
0
-40
-20
0
20
40
60
(ii) VDD2 = 3.3V, Cpeak = 100 pF, Rlimit = 250Ω
Speed Improvement
A peaking capacitor can be placed across the input current
limit resistor (Figure 11) to achieve enhanced speed
performance. The value of the peaking cap is dependent on
the rise and fall time of the input signal and supply voltages
and LED input driving current (IF). Figure 12 shows significant
improvement of propagation delay and pulse width distortion
with added 100-pF peak capacitor at driving current of 6 mA
and 5V power supply.
Broadcom
- 11 -
80
100
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
Common-Mode Rejection for ACPL-W70L AND ACPL-K73L
Common-Mode Rejection for ACPL-W70L
AND ACPL-K73L
For conditions where IF is close to the switching threshold (ITH),
CML also depends on the extent that ILP and ILN balance each
other. In other words, any condition where common-mode
transients cause a momentary decrease in IF (i.e., when
dVCM/dt>0 and |IFP| > |IFN|, referring to Table 1) causes
common-mode failure for transients that are fast enough.
Figure 13 shows the recommended driving circuit for the
ACPL-W70L and ACPL-K73L for optimal common-mode
rejection performance. Two LED-current setting resistors are
used instead of one. This is to balance the common-mode
impedance at LED anode and cathode. Common-mode
transients can capacitively couple from the LED anode (or
cathode) to the output-side ground causing current to be
shunted away from the LED (which can be bad if the LED is on)
or conversely cause current to be injected into the LED (bad if
the LED is meant to be off ). Figure 14 shows the parasitic
capacitances that exist between LED anode/cathode and
output ground (CLA and CLC). Also shown in Figure 14 on the
input side is an AC-equivalent circuit.
Likewise, for common-mode transients that occur when the
LED is off (i.e., CMH, since the output is high), if an imbalance
between ILP and ILN results in a transient IF equal to or greater
than the switching threshold of the optocoupler, the transient
signal can cause the output to spike below 2V (which
constitutes a CMH failure).
By using the recommended circuit in Figure 13, good CMR can
be achieved. The resistors recommended in Figure 13 include
both the output impedance of the logic driver circuit and the
external limiting resistor. The balanced ILED-setting resistors
help equalize the common-mode voltage change at anode and
cathode to reduce the amount by which ILED is modulated from
transient coupling through CLA and CLC.
Table 1 indicates the directions of ILP and ILN flow depending
on the direction of the common-mode transient. For transients
occurring when the LED is on, common-mode rejection (CML,
since the output is in the low state) depends upon the amount
of LED current drive (IF).
Figure 13 Recommended Drive Circuit for ACPL-W70L and ACPL-K73L for High-CMR
Rtotal =300Ω for VDD=3.3V
= 580Ω for VDD=5V
1/2R total
V DD2
V DD1
VO
0.1μF
1/2R total
74LS04 OR ANY TOTEMPOLE OUTPUT LOGIC GATE
GND 2
SHIELD
GND 1
Figure 14 AC Equivalent of ACPL-W70L and ACPL-K73L
½ R total
V DD2
ILP
C LA
½ R total
VO
0.1μF
15pF
ILN
C LC
SHIELD
GND 2
Broadcom
- 12 -
ACPL-W70L-000E and ACPL-K73L-000E
Data Sheet
CMR with Other Drive Circuits
Table 1 Effects of Common-Mode Pulse Direction on Transient ILED
If |ILP| < |ILN|,
If |ILP| > |ILN|,
LED IF Current Is Momentarily: LED IF Current Is Momentarily:
If dVCM/dt Is:
Then ILP Flows:
And ILN Flows:
Positive (>0)
Away from LED
anode through CLA
Away from LED
cathode through CLC
Increased
Decreased
Negative (