ISO7221ADR

The ISO7220x and ISO7221x family devices are dualchannel digital isolators. To facilitate PCB layout, the
channels are oriented in the same direction in the
ISO7220x and in opposite directions in the ISO7221x.
These devices have a logic input and output buffer
separated by TI’s silicon-dioxide (SiO2) isolation
barrier, providing galvanic isolation of up to 4000 VPK
per VDE. Used in conjunction with isolated power
supplies, these devices block high voltage and isolate
grounds, as well as prevent noise currents on a data
bus or other circuits from entering the local ground
and interfering with or damaging sensitive circuitry.
A binary input signal is conditioned, translated to a
balanced signal, then differentiated by the capacitive
isolation barrier. Across the isolation barrier, a
differential comparator receives the logic transition
information, then sets or resets a flip-flop and the
output circuit accordingly. A periodic update pulse is
sent across the barrier to ensure the proper dc level of
the output. If this dc-refresh pulse is not received
every 4 μs, the input is assumed to be unpowered or
not being actively driven, and the failsafe circuit drives
the output to a logic high state.
The small capacitance and resulting time constant
provide fast operation with signaling rates available
from 0 Mbps (DC) to 150 Mbps (The signaling rate of
a line is the number of voltage transitions that are
made per second expressed in the units bps). The Aoption, B-option, and C-option devices have TTL input
thresholds and a noise filter at the input that prevents
transient pulses from being passed to the output of
the device. The M-option devices have CMOS VCC/2
input thresholds and do not have the input noise filter
and the additional propagation delay.
The ISO7220x and ISO7221x family of devices
require two supply voltages of 2.8 V (C-Grade), 3.3 V,
5 V, or any combination. All inputs are 5-V tolerant
when supplied from a 2.8-V or 3.3-V supply and all
outputs are 4-mA CMOS.
The ISO7220x and ISO7221x family of devices are
characterized for operation over the ambient
temperature range of –40°C to +125°C.