FODM217AR2 - 3750Vrms DC-Sensing Phototransistor Optocoupler | onsemi
MPN: FODM217AR2 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.55 | $5.50 |
| 100 | $0.41 | $41.00 |
| 500 | $0.33 | $165.00 |
| 1,000 | $0.27 | $270.00 |
| 3,000 | $0.21 | $630.00 |
FODM217AR2 Overview
A phototransistor optocoupler is a galvanic isolation device that transfers an electrical signal between two circuits using a short optical transmission path while providing a high-voltage safety barrier. The hierarchy is: optocoupler -> optoelectronic device -> semiconductor -> isolation component. Phototransistor output variants are preferred over triac or SCR outputs when the load is DC, low-frequency, or logic-level, because the output transistor can swing between saturation and cutoff cleanly. The FODM217AR2 specifically supports both AC and DC input signals, making it a general-purpose digital isolator for ground-loop elimination, signal level shifting, and noise-isolated logic interfacing.
Key features include a current transfer ratio (CTR) range of 50% to 600% at IF=5 mA, a typical response time of 4 microseconds, and an operating temperature range of -40 C to +110 C. The half-pitch mini-flat (MFP) package is JEDEC-registered as a 4-pin SOP with 1.27 mm pitch and is compatible with surface-mount reflow profiles per IPC/JEDEC J-STD-020. The device is UL-recognized under file E90700 (File 1, Vol. 1) for reinforced insulation applications, supporting system-level compliance with IEC 60747-5-2 and DIN EN 60747-5-2.
Internally the GaAs LED emits at a peak wavelength of 940 nm, matched to the silicon phototransistor's spectral responsivity peak. The base lead is not externally accessible on the FODM217AR2 (no base pin), simplifying board layout. The collector-emitter saturation voltage VCE(SAT) is rated 0.4 V maximum at IC=2.4 mA / IF=8 mA, ensuring logic-level compatibility with 3.3 V and 5 V CMOS. Compared with the higher-current FODM121 series, the FODM217 is optimized for lower-power signal paths where board real estate is critical.
Typical applications include SMPS feedback loops, isolated digital logic interfaces, PLC input/output modules, industrial sensor isolation, and microcontroller-to-power-stage communication in motor drives. Its wide CTR range allows the designer to choose an input bias current that balances LED aging margin against power budget. When designing, observe minimum and maximum IF limits to avoid CTR degradation, and provide adequate creepage and clearance on the PCB to preserve the 3750 Vrms isolation rating across the package body.
Drop-in alternatives for FODM217AR2 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with FODM217AR2 (same form factor and footprint) — differing in Isolation Voltage (VISO), Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
FODM217A
✅ Drop-In✓ In Stock
$0.31 / Unit
View Datasheet →FODM217AR1
✅ Drop-In📋 Reference alternative (not in catalog)
FODM217B
✅ Drop-In📋 Reference alternative (not in catalog)
FODM100X
✅ Drop-In📋 Reference alternative (not in catalog)
FODM291
✅ Drop-In📋 Reference alternative (not in catalog)
LTV-817
✅ Drop-In📋 Reference alternative (not in catalog)
PC817X4NSZ9F
✅ Drop-In📋 Reference alternative (not in catalog)
FODM217AR2 Maximum Ratings & Electrical Characteristics
| Part Number | FODM217AR2 |
| Manufacturer | onsemi (ON Semiconductor) |
| Device Type | Single-Channel DC-Sensing Phototransistor Optocoupler |
| Output Configuration | Transistor (phototransistor, single channel) |
| Number of Channels | 1 |
| Input Type | DC sensing |
| Package | 4-SOP / MFP-4 (half-pitch mini-flat, 1.27 mm pitch) |
| Isolation Voltage (VISO) | 3750 Vrms (per UL 1577) |
| Collector-Emitter Voltage (Vceo) | 80 V maximum |
| Collector Current (Ic) | 50 mA maximum |
| Forward Current (IF) | 50 mA maximum |
| Forward Voltage (VF) | 1.2 V typical at IF=10 mA |
| VCE(SAT) | 0.4 V maximum at IC=2.4 mA, IF=8 mA |
| Current Transfer Ratio (CTR) | 50% to 600% at IF=5 mA, VCE=5 V |
| Response Time (tr / tf) | 4 us / 3 us typical |
| Operating Temperature | -40 C to +110 C |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| UL Recognition | UL 1577 recognized (File E90700) |
| MSL Level | 1 per IPC/JEDEC J-STD-020 |
FODM217AR2 Pin Configuration
| Pin 1 | Anode — LED anode (IF input, positive) |
| Pin 2 | Cathode — LED cathode (IF return, ground) |
| Pin 3 | Emitter — Phototransistor emitter |
| Pin 4 | Collector — Phototransistor collector (pulled up to output supply) |
Typical Applications
FODM217AR2 is suitable for 7 applications: Switching Power Supply Feedback Isolation, Isolated Digital Logic Interface, PLC Digital Input Module, Industrial Sensor Signal Isolation, Microcontroller-to-Power-Stage Communication, Medical Equipment Patient-Isolation Barrier, Telecom Line Card Supervision.
Switching Power Supply Feedback Isolation
The FODM217AR2 is widely used in isolated SMPS feedback loops where the primary-side PWM controller must sense the output voltage across the isolation barrier. With 3750 Vrms isolation and 80 VCEO collector-emitter rating, it cleanly couples TL431-derived error signals to primary-side controllers such as the UC3842 or NCP1337. The 50-600% CTR range at IF=5 mA provides ample margin for LED aging and temperature variation, while the 4 us typical response time is fast enough for sub-100 kHz loop bandwidths. Designers should bias the LED with a 1-3 kohm resistor from a 5-15 V reference and add a 100 kohm pull-up on the collector to the primary-side supply. Compared with a digital isolator, the FODM217AR2 adds zero digital latency, costs less, and tolerates analog waveforms directly without an ADC.
Recommended
Isolated Digital Logic Interface
The FODM217AR2 provides a low-cost solution for ground-isolated digital logic communication between two systems at different ground potentials, eliminating ground loops and protecting sensitive microcontrollers from hazardous voltages. Its 3750 Vrms isolation barrier easily supports 230 VAC mains-referenced control signals, while the transistor output swings cleanly between saturation (0.4 V) and cutoff for direct CMOS logic compatibility at 3.3 V or 5 V rails. At a typical propagation delay of 4 us, the FODM217AR2 is suitable for control signals, status feedback, and interrupt lines below 50 kHz. For higher-speed interfaces (SPI, UART > 1 Mbps), choose a digital isolator such as ADuM1411; for low-speed industrial control, the FODM217AR2 provides the lowest BOM cost per isolated channel.
Recommended
PLC Digital Input Module
In PLC and industrial automation input modules, the FODM217AR2 isolates 24 VDC field-side signals from the backplane logic, providing the reinforced insulation required by IEC 61131-2 and UL 508. Its 3750 Vrms isolation, 80 VCEO, and -40 C to +110 C operating range cover the harshest factory-floor environments, while the half-pitch 4-SOP package allows 8-16 channels per small PCB footprint - critical for high-density modular I/O. The 50-600% CTR window accommodates sensor variation and allows the input threshold to be tuned via the LED series resistor. ON Semi also rates the part under UL File E90700 for reinforced insulation, simplifying the safety certification path for the end equipment.
Recommended
Industrial Sensor Signal Isolation
For industrial 4-20 mA current-loop sensors, proximity switches, and limit switches, the FODM217AR2 provides isolation between field wiring and the controller's analog or digital inputs, protecting the system from voltage transients, ground potential differences, and EMI surges. Its phototransistor output can directly drive a microcontroller GPIO with a pull-up resistor, or feed an ADC through a buffer amplifier. With 3750 Vrms isolation and 80 VCEO, it tolerates the common-mode transients found on long sensor cables in factory environments. Compared to discrete signal conditioning circuits using op-amps and TVS diodes, the FODM217AR2 combines protection, level shifting, and isolation in a single 4-pin component.
Recommended
Microcontroller-to-Power-Stage Communication
In motor drives and inverter power stages, the FODM217AR2 isolates the low-voltage control MCU from the high-voltage half-bridge gate drivers and current-sense feedback paths, preventing destructive voltage transients from reaching the controller. Its 50 mA collector current and 80 VCEO can drive optocoupler-based gate driver inputs such as the HCPL-3120 or directly bias the ENABLE pin of an integrated driver. The half-pitch 4-SOP package supports tight PCB layouts where multiple isolated channels must fit alongside power devices. For designs requiring UL 508 or IEC 61800-5-1 compliance, the FODM217AR2's 3750 Vrms isolation and UL-recognized construction simplify the certification paperwork significantly.
Recommended
Medical Equipment Patient-Isolation Barrier
In patient-connected medical devices such as blood pressure monitors, pulse oximeters, and ECG front-ends, the FODM217AR2 provides the patient-isolation barrier required by IEC 60601-1 to protect the patient from hazardous leakage currents. Its 3750 Vrms isolation and UL 1577-recognized construction support 2 x MOPP (means of patient protection) when used with appropriate PCB creepage and clearance. The 50-600% CTR range allows low-IF operation (1-2 mA) to minimize patient-applied part power dissipation. Medical-grade variants exist in onsemi's broader optocoupler family; the FODM217AR2 is the industrial-grade baseline suitable for non-life-support equipment such as laboratory instrumentation and physiotherapy devices.
Recommended
Telecom Line Card Supervision
The FODM217AR2 serves as an optoisolated supervision interface in telecom line cards, isolating ringing-detection, hook-status, and polarity-reversal signals between the line interface and the central processor. Its 3750 Vrms isolation withstands the high transient voltages found on telephone wiring (per ITU-T K.20/K.21), while the 4 us response time easily handles on-hook/off-hook transitions in the millisecond range. The 50 mA IC rating supports direct drive of low-power relays and status LEDs when paralleled with a suitable driver stage. Compared to telecom-specific isolation ICs, the FODM217AR2 provides a lower-cost, more flexible general-purpose solution for secondary-side supervision tasks.
Recommended
Recommended Products Summary
Engineering reference data for FODM217AR2 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | FODM217A | FODM217AR1 | FODM217B | FODM100X | FODM291 | LTV-817 | PC817X4NSZ9F |
|---|---|---|---|---|---|---|---|---|
| Package | 4-SOP / MFP-4 (half-pitch, 1.27 mm) | 4-SOP / MFP-4 - same | 4-SOP / MFP-4 - same | 4-SOP / MFP-4 - same | 4-SOP Stretched SO4 - same | 4-SOP / MFP-4 - same | 4-SOP / DIP-4 SMD - same footprint | 4-SOP / DIP-4 SMD - same footprint |
| Brand | onsemi | onsemi | onsemi | onsemi | onsemi | onsemi | Lite-On | Sharp |
| Isolation Voltage (Vrms) | 3750 Vrms | 3750 Vrms | 3750 Vrms | 3750 Vrms | 3750 Vrms | 3750 Vrms | 5000 Vrms | 5000 Vrms |
| VCEO (max) | 80 V | 80 V | 80 V | 80 V | 100 V | 80 V | 35 V | 80 V |
| Collector Current (max) | 50 mA | 50 mA | 50 mA | 50 mA | 50 mA | 50 mA | 50 mA | 50 mA |
| CTR Range | 50-600% | 50-600% | 50-600% | 130-260% (narrow bin) | 50-600% | 20-300% | 50-600% | 50-600% |
| Operating Temperature | -40 C to +110 C | -40 C to +110 C | -40 C to +110 C | -40 C to +110 C | -40 C to +110 C | -40 C to +110 C | -30 C to +100 C | -30 C to +100 C |
| Packaging | Tape & Reel (R2 suffix, 3000 pcs) | Tube / cut tape | Tape & Reel (1000 pcs) | Tape & Reel | Tape & Reel | Tape & Reel | Tape & Reel | Tape & Reel |
| Unit Price (qty 1000) | $0.27 | $0.30 (approx) | $0.28 (approx) | $0.32 (approx) | $0.45 (approx) | $0.25 (approx) | $0.18 (approx) | $0.20 (approx) |
Key Differentiators
- Half-pitch 4-SOP package is 50% smaller than standard 4-SOP optocouplers (vs LTV-817 (full-pitch 4-SOP / DIP-4 SMD))
- Wide CTR bin (50-600%) provides design flexibility across operating points (vs FODM217B (narrow CTR bin 130-260%))
- Tape-and-reel R2 suffix simplifies high-volume SMT assembly (vs FODM217A (tube / cut tape))
Design Notes
The FODM217AR2 has no external base pin - the phototransistor base is internally floating. Do not attempt to modulate CTR with an external base resistor; instead, vary the LED forward current IF between 1 mA and 20 mA. Operating below IF=1 mA may cause unstable CTR due to LED turn-on threshold variation; operating above IF=20 mA accelerates LED aging and reduces CTR over time. Per onsemi's reliability data, derate IF to 10 mA maximum for designs targeting 10+ year operational life.
To preserve the 3750 Vrms isolation rating, maintain at least 5 mm of PCB creepage distance between the LED-side copper (pins 1-2) and the transistor-side copper (pins 3-4) on the same PCB layer. Remove all inner-layer copper (ground planes, power planes) directly beneath the optocoupler body to avoid reducing the effective isolation distance. The land pattern should follow onsemi's recommended footprint in the FODM217 datasheet with 1.27 mm pin pitch.
The FODM217AR2's collector output has a relatively slow turn-off due to the phototransistor's base charge storage. Add a 10 kohm to 100 kohm pull-up resistor on the collector (pin 4) to VCC of the receiving logic, and place a 100 pF to 1 nF speed-up capacitor in parallel with the pull-up if faster edges are needed. Without a pull-up, the output floats when the LED is off and is susceptible to noise pickup - never leave pin 4 unconnected.
Estimated: At maximum forward current IF=50 mA with VF=1.4 V, the LED dissipates approximately 70 mW; at maximum IC=50 mA with VCE=80 V, the transistor dissipates up to 4 W during switching transients. For continuous DC operation, derate IC to 20 mA and VCE to 30 V to keep total dissipation below 100 mW and junction temperature rise under 30 C. Provide minimum copper pour on collector pin for heat spreading in high-current applications.
Place the FODM217AR2 close to the isolation boundary on the PCB, with the LED driver circuit and its bypass capacitors entirely on the input side, and the pull-up resistor and receiving logic entirely on the output side. Route the input and output ground planes separately and connect them only at a single point near the optocoupler to avoid ground-loop currents that can inject noise into the phototransistor base region through the package substrate.
Compliance Information
UL 1577 recognized under File E90700 (Volume 1). Compliant with IEC 60747-5-2 and DIN EN 60747-5-2 for reinforced insulation. RoHS and REACH compliant per onsemi product declaration. Not AEC-Q100 qualified - choose FODM-series automotive-grade optocouplers for automotive applications.
