a
FEATURES
Isolation Test Voltage: To 3.5 kV rms
Five Isolated Logic Lines: Available in Six I/O Configurations
Logic Signal Bandwidth: 20 MHz (min)
CMV Transient Immunity: 10 kV/ s min
Waveform Edge Transmission Symmetry: 1 ns
Field and System Output Enable/Three-State Functions
Performance Rated Over 鈥?5 C to +85 C
UL1950, IEC950, EN60950 Certification (VDE, CE, Pending)
APPLICATIONS
PLC/DCS Analog Input and Output Cards
Communications Bus Isolation
General Data Acquisition Applications
IGBT Motor Drive Controls
High Speed Digital I/O Ports
F0
High Speed, Logic Isolator
AD261
FUNCTIONAL BLOCK DIAGRAM
THR
STA EE-
TE
LINE 0
LATCH
D
E
LATCH
D
E
LATCH
D
E
S0
F1
THR
STA EE-
TE
LINE 1
2
S1
F2
THR
STA EE-
TE
LINE 2
3
S2
F3
LATCH
D
E
LATCH
LINE 3
EE-
THRATE
ST
4
S3
F4
D
E
LINE 4
EE-
THRATE
ST
5
S4
ENABLE
FLD 17
6
ENABLE
SYS
GENERAL DESCRIPTION
+5V dc
FLD 16
5V RTN
FLD 15
+5V dc
5Vdc RTN
+5V dc
7
+5V dc
SYS
5V RTN
SYS
The 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.
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
鹵
1 ns of the input so the AD261 can be used to accu-
rately isolate time-based PWM signals.
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.
The isolation barrier of the AD261 B Grade is 100% tested
as high as 3.5 kV rms (system to field). The barrier design also
provides excellent common-mode transient immunity from
10 kV/碌s common-mode voltage excursions of field side termi-
nals relative to the system side, with no false output triggering
on either side.
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. This guarantees the output is always valid 10
碌s
after
a fault condition or after the power-up reset interval.
5Vdc RTN
8
FIELD
TYPICAL MODEL
SYSTEM
(AD261-2)
PRODUCT HIGHLIGHTS
Six Isolated Logic Line I/O Configurations Available:
The
AD261 is available in six pin-compatible versions of I/O con-
figurations to meet a wide variety of requirements.
Wide Bandwidth with Minimal 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
鹵
1 ns (total) for positive vs. negative transition.
3.5 kV rms Test Voltage Isolation Rating:
The 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.
High Transient Immunity:
The AD261 rejects common-
mode transients slewing at up to 10 kV/碌s without false trigger-
ing or damage to the device.
(Continued
on page
5)
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
漏 Analog Devices, Inc., 1997
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