Isolation and signal transfer
The 4N37FR2VM is a single-channel optocoupler with a DC input LED and a phototransistor output with base access. The 7500Vpk isolation rating is the peak repetitive voltage the package withstands between input and output — this is the spec that governs creepage and clearance in mains-referenced or high-side gate-drive circuits where galvanic separation is mandatory. Minimum current transfer ratio of 100% at 10 mA forward current means the output transistor can sink at least as much collector current as the LED draws — a 10 mA input reliably produces 10 mA or more at the output, enough to drive a logic gate input or a low-power relay coil without an additional gain stage. Typical turn-on and turn-off times of 2 µs each set the switching ceiling — the part handles 250 kHz data rates comfortably, but above that the output rise time stretches and the pulse-width fidelity degrades. For 50/60 Hz AC line sensing or slow digital isolation (GPIO, fault flags, relay drive), this is more than adequate.
Housed in a 6-SMD Gull Wing package (Supplier Device Package 6-SMD), the part is a surface-mount variant of the industry-standard 6-pin DIP optocoupler footprint. The 6-SMD Gull Wing outline mates with the same 7.62 mm (300 mil) pin row spacing as the through-hole DIP-6, so a single PCB layout can accommodate either form factor by populating the SMD pads or the through-hole holes. Supplied on Tape & Reel (TR) — the standard packaging for automated pick-and-place assembly. The operating temperature range of -55°C to 100°C covers industrial and extended-temperature environments, though the 100°C upper limit is below the 125°C junction rating common in automotive-grade optocouplers.
Obsolete — sourcing options
onsemi has marked the 4N37FR2VM as Obsolete. Sourcing is through independent distribution and surplus channels — the part is available against RFQ, with lot traceability and date code confirmed at quote time. For new designs, a functionally equivalent optocoupler from the same 4N37 family (e.g., a through-hole DIP-6 variant) may serve as a drop-in replacement after verifying the package and CTR grade.