5300 Vrms reinforced isolation in a 4-SMD gull-wing package
The DC input side drives an IR LED (typical forward voltage 1.25 V, max continuous forward current 60 mA), and the phototransistor output handles up to 70 V at 50 mA per channel. The -3 CTR bin (100% to 200% at 10 mA forward current) sits between the -2 and -4 gain tiers, giving a predictable drive margin for logic-level coupling without overloading the output side.
CTR bin -3: what the 100–200% range means for your design
The current transfer ratio (CTR) of 100% to 200% at 10 mA forward current defines how much collector current the phototransistor can sink for a given LED drive. At the minimum 100% CTR, 10 mA in gives at least 10 mA out — enough to saturate a TTL or CMOS input with margin. The 200% ceiling means the same input can drive a higher-impedance load without needing a separate gain stage. The -3 bin is the most commonly specified mid-range gain for general-purpose isolation; if your load requires less than 5 mA output, the -2 bin (63–125%) saves LED drive current, while the -4 bin (160–320%) handles degraded LED output over temperature or lifetime.
That puts the usable switching frequency around 50–100 kHz for digital isolation — adequate for status feedback, relay drivers, and isolated serial links at moderate baud rates. The 400 mV Vce(sat) maximum at rated collector current keeps the output drop low enough to drive 3.3 V logic directly.