a
High Speed, Logic Isolator
AD261
FEATURES
FUNCTIO NAL BLO CK D IAGRAM
Isolation Test Voltage: To 3.5 kV rm s
Five Isolated Logic Lines: Available in Six I/ O Configurations
Logic Signal Bandw idth: 20 MHz (m in)
CMV Transient Im m unity: 10 kV/ s m in
Waveform Edge Transm ission Sym m etry: ؎1 ns
Field and System Output Enable/ Three-State Functions
Perform ance Rated Over –25؇C to +85؇C
UL1950, IEC950, EN60950 Certification (VDE, CE, Pending)
LATCH
THREE-
F0
F1
F2
F3
F4
D
E
LINE 0
LINE 1
LINE 2
LINE 3
LINE 4
S0
STATE
LATCH
THREE-
STATE
D
E
2
3
4
S1
S2
LATCH
THREE-
STATE
D
E
APPLICATIONS
LATCH
PLC/ DCS Analog Input and Output Cards
Com m unications Bus Isolation
General Data Acquisition Applications
IGBT Motor Drive Controls
D
S3
S4
THREE-
STATE
E
LATCH
D
5
6
THREE-
STATE
E
High Speed Digital I/ O Ports
ENABLE
+5V dc
17
ENABLE
+5V dc
SYS
FLD
+5V dc
+5V dc
16
15
7
8
GENERAL D ESCRIP TIO N
FLD
SYS
T he AD261 is designed to isolate five digital control signals
to/from a microcontroller and its related field I/O components.
Six models allow all I/O combinations from five input lines to
five output lines, including combinations in between. Every
AD261 effectively replaces up to five opto-isolators.
5Vdc RTN
5Vdc RTN
5V RTN
5V RTN
SYS
FLD
FIELD
SYSTEM
TYPICAL MODEL
(AD261-2)
Each line of the AD261 has a bandwidth of 20 MHz (min) with
a propagation delay of only 14 ns, which allows for extremely
fast data transmission. Output waveform symmetry is maintained
to within ±1 ns of the input so the AD261 can be used to accu-
rately isolate time-based PWM signals.
P RO D UCT H IGH LIGH TS
Six Isolated Logic Line I/O Configurations Available: T he
AD261 is available in six pin-compatible versions of I/O con-
figurations to meet a wide variety of requirements.
All field or system output pins of the AD261 can be set to a high
resistance three-state level by use of the two enable pins. A field
output three-stated offers a convenient method of presetting
logic levels at power-up by use of pull-up/down resistors. Sys-
tem side outputs being three-stated allows for easy multiplexing
of multiple AD261s.
Wide Bandwidth with Minim al Edge Error: The AD261
affords extremely fast isolation of logic signals due to its 20 MHz
bandwidth and 14 ns propagation delay. It maintains a wave-
form input-to-output edge transition error of typically less than
±1 ns (total) for positive vs. negative transition.
3.5 k V r m s Test Volta ge Isola tion Ra tin g: T he AD261
B Grade is rated to operate at 1.25 kV rms and is 100% pro-
duction tested at 3.5 kV rms, using a standard ADI test method.
T he isolation barrier of the AD261 B Grade is 100% tested
as high as 3.5 kV rms (system to field). T he barrier design also
provides excellent common-mode transient immunity from
10 kV/µs common-mode voltage excursions of field side termi-
nals relative to the system side, with no false output triggering
on either side.
High Tr a nsient Im m unity: T he AD261 rejects common-
mode transients slewing at up to 10 kV/µs without false trigger-
ing or damage to the device.
Each output is updated within nanoseconds by input logic tran-
sitions, the AD261 also has a continuous output update feature
that automatically updates each output based on the dc level of
the input. T his guarantees the output is always valid 10 µs after
a fault condition or after the power-up reset interval.
(Continued on page 5)
REV. 0
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use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
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© Analog Devices, Inc., 1997