Scenario: Isolating a 24V PLC output to a 3.3V microcontroller input.
| Parameter | Typical Expected Value | Why It Matters | | :--- | :--- | :--- | | | 3,750 Vrms – 5,000 Vrms | Safety compliance (UL, VDE). For A1458, check if it meets reinforced insulation. | | Current Transfer Ratio (CTR) | 50% – 600% (depending on bin) | The gain of the coupler. Low CTR (<50%) indicates an old or slow device. | | Rise/Fall Time (tr/tf) | 2 – 18 µs | Determines max switching speed (typically < 100 kHz for standard types). | | Input Forward Current (IF) | 50 mA (max) / 10 mA (typical) | Prevents burning out the internal LED. | a1458 optocoupler datasheet
– I see no common industry optocoupler named “A1458.” Could it be a misreading of: Scenario: Isolating a 24V PLC output to a 3
Optimized for digital signal transmission with minimal delay (35 ns at 10 kHz in some configurations). | | Current Transfer Ratio (CTR) | 50%
These performance specifications define how the A1458 behaves under normal working conditions. Input Diode Specifications Typical 1.5V (at Reverse Leakage Current ( IRcap I sub cap R ): Maximum Input Capacitance ( CINcap C sub cap I cap N end-sub ): 60 pF (at Output Detector Specifications Logic High Output Current ( IOHcap I sub cap O cap H end-sub ): Maximum when the input LED is off. Logic Low Output Voltage ( VOLcap V sub cap O cap L end-sub ): Maximum 0.6V when the input LED is active ( Supply Current ( ICCHcap I sub cap C cap C cap H end-sub ICCLcap I sub cap C cap C cap L end-sub
Do not run any copper traces, power planes, or ground planes underneath the optocoupler body between the input (Pins 1-4) and output (Pins 5-8) sides. Maintain a minimum creepage and clearance distance of at least 7mm to 8mm. Use Bypass Capacitors: Always place a ceramic bypass capacitor between Pin 8 ( VCCcap V sub cap C cap C end-sub ) and Pin 5 ( GNDcap G cap N cap D
Inverter topologies, solar power converters, and variable-frequency motor drives utilize High-Power MOSFETs or IGBTs. The A1458 isolates the high-voltage power stage while sending sharp, distortion-free switching control pulses down to the gate-driver circuit. Single Channel, High Speed Optocouplers Technical Data