850 mA switch in a flexible topology controller
The LT1082IQ#TRPBF is a switching regulator supporting step-up, step-down, buck, boost, flyback, and forward converter topologies with an 850 mA switch. Input range is 3 V to 75 V; output can be positive, negative, or isolated. Switching frequency runs 12 kHz to 60 kHz.
The ROHS3 compliance and active lifecycle status mean no last-time-buy clock is ticking; it can be designed into new BOMs without an obsolescence watch.
What the 850 mA switch rating means for your load budget
The 850 mA figure is the switch current limit, not the output current — in a boost converter the output current will be lower than 850 mA by the ratio of Vin/Vout, and in a flyback it depends on the transformer turns ratio and duty cycle. For a 5 V output from a 12 V rail, expect around 300 mA to 400 mA continuous output before the switch hits its limit. The adjustable output down to 1.244 V reference gives flexibility for low-voltage rails, and the 100 V switch rating handles high-voltage flyback outputs like 48 V or 72 V bias rails.
Sourcing and lifecycle posture
For a dual-sourcing review, the closest functional peer in the family is the LT1373IS8#PBF, which runs at 250 kHz and delivers 1.5 A switch current in an SOIC-8, but that part lacks the 75 V input range of this device. No pin-compatible second source exists, so BOM resilience depends on stocking this specific order code.