The ISO7220 and ISO7221 are dual-channel digital isolators. To facilitate PCB layout, the channels are oriented in the same direction in the ISO7220 and in opposite directions in the ISO7221. 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, isolate grounds, and 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 (bits per second). The A-, B- 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.
These 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.
These devices are characterized for operation over the ambient temperature range of –40°C to 125°C.
25-Mbps Signaling Rate
Low Channel-to-Channel Output Skew; 1-ns max
Low Pulse-Width Distortion (PWD); 1-ns max
Low Jitter Content; 1 ns Typ at 150 Mbps
50 kV/µs Typical Transient Immunity
Operates with 2.8-V (C-Grade), 3.3-V or 5-V Supplies
4-kV ESD Protection
High Electromagnetic Immunity
–40°C to 125°C Operating Range
Typical 28-Year Life at Rated Voltage (see application report High-Voltage Lifetime of the ISO72x Family of Digital Isolators(SLLA197))
VDE Basic Insulation with 4000-VPK VIOTM, 560 VPK VIORM per DIN EN 60747-5-5 (VDE 0884-5) and DIN EN 61010-1 (VDE 0411-1)
2500 VRMS Isolation per UL 1577
CSA Approved for Component Acceptance Notice 5A and IEC 60950-1