A1458 Optocoupler Datasheet <2026>

In a flyback converter, the A1458 provides isolated feedback from the secondary side to the primary PWM controller. The TL431 drives the A1458's LED proportionally to the output voltage.

The part number "A1458" can occasionally be a proprietary house number (e.g., from Vishay, Toshiba, or a Chinese manufacturer) or a specific batch code. In many historical databases, the A1458 aligns closely with a DIP-4 transistor output optocoupler . We will treat it as a standard phototransistor optocoupler with specifications similar to the LTV-817 or KPS2801. Always refer to the manufacturer-specific datasheet for your batch. A1458 Optocoupler Datasheet

: Isosating data lines and protecting communication equipment from power surges. In a flyback converter, the A1458 provides isolated

The is a reliable, cost-effective solution for basic galvanic isolation. While it lacks the speed of advanced logic gate optocouplers, its strength lies in its simplicity, wide CTR range, and robust 5kV isolation. By understanding its datasheet—paying close attention to CTR ranking, derating curves, and pinout—you can confidently integrate it into power supplies, industrial controls, and isolated communication interfaces. In many historical databases, the A1458 aligns closely

| Parameter | Symbol | Min | Typ | Max | Unit | Test Conditions | | :--- | :---: | :---: | :---: | :---: | :---: | :--- | | | CTR | 50% | - | 600% | - | $I_F=5mA, V_CE=5V$ | | Collector-Emitter Saturation Voltage | $V_CE(sat)$ | - | 0.1 | 0.2 | V | $

When the LED is on, the phototransistor conducts, pulling the output low. When off, the output is pulled high.

| Part Number | CTR (%) | Isolation | Package | Cost | |-------------|---------|-----------|---------|------| | A1458 | 50–600 | 5000 Vrms | DIP-4 | Low | | PC817 | 50–600 | 5000 Vrms | DIP-4 | Low | | 4N25 | 20–100 | 2500 Vrms | DIP-6 | Low | | H11L1 | (logic out) | 2500 Vrms | DIP-6 | Medium |