A1458 Optocoupler Datasheet | Linux |

Scenario: Isolating a 24V PLC output to a 3.3V microcontroller input.

Components:

Operation: When PLC output is high (24V), LED turns on, phototransistor conducts, output pin pulled low. When PLC output low, LED off, output pulled high by R2.

The isolation barrier is the primary reason to use the A1458. The datasheet provides the following isolation parameters:

| Parameter | Symbol | Conditions | Value | Unit | |-----------|--------|-------------|-------|------| | Isolation Voltage | V_ISO | Ta=25°C, 60Hz, 1 sec | 5,000 | Vrms | | Isolation Resistance | R_IO | V_IO = 500V | 10^12 (min) | Ω | | Isolation Capacitance | C_IO | V_IO = 0V, f=1MHz | 0.8 (typ) | pF |

Certifications: Many A1458 variants carry UL 1577, VDE 0884 (reinforced insulation), and CSA approvals. Always check the specific datasheet for regulatory marks if your design requires safety certification.

| Parameter | Symbol | Min | Max | Unit | |----------------------------|--------|------|-------|-------| | Forward current (LED) | IF | - | 50 | mA | | Reverse voltage (LED) | VR | - | 6 | V | | Collector-emitter voltage | VCEO | - | 80 | V | | Emitter-collector voltage | VECO | - | 7 | V | | Collector current | IC | - | 50 | mA | | Total power dissipation | Ptot | - | 150 | mW | | Isolation voltage (1 min) | VISO | - | 5000 | Vrms | | Operating temperature | Topr | -55 | +110 | °C | | Storage temperature | Tstg | -55 | +125 | °C |

This is arguably the most important dynamic parameter. CTR is the ratio of the output current ($I_C$) to the input current ($I_F$), expressed as a percentage.

$$CTR = \fracI_CI_F \times 100%$$

For standard optocouplers like the A1458, the CTR can range anywhere from 50% to 300% depending on the specific bin/grade.

Pro Tip: CTR degrades over time and with heat. Always design your circuit with a safety margin.

If the part physically has "A1458" printed on it:

| Parameter | Symbol | Test Condition | Min | Typ | Max | Unit | |--------------------|--------|----------------------|-----|-----|-----|------| | Rise time | t_r | IF = 10 mA | - | 4 | 8 | µs | | Fall time | t_f | IF = 10 mA | - | 3 | 6 | µs | | Turn-on time | t_on | IF = 10 mA | - | 6 | 10 | µs | | Turn-off time | t_off | IF = 10 mA | - | 5 | 8 | µs |

The A1458 optocoupler datasheet often includes reference circuits. Here are two common ones.

The A1458 is likely a standard DIP-4 phototransistor optocoupler with medium speed (10 µs) and 3.75kV isolation. Before purchasing:

Action Step: Search the manufacturer prefix (e.g., "Sharp A1458" or "Vishay A1458") – the first three letters often reveal the true brand.

Need help comparing the A1458 to a modern drop-in replacement? Let me know your specific use case (e.g., motor drive, SMPS feedback, or Arduino isolation). a1458 optocoupler datasheet

The Go to product viewer dialog for this item. (often referred to as A1458) is a high-speed, single-channel logic gate optocoupler manufactured by Broadcom (formerly Avago). It is designed to bridge the gap between high-speed digital circuits while providing excellent electrical isolation. ⚡ Key Specifications

According to Broadcom (via Heisener), this component is built for speed and reliability. Propagation Delay: Maximum 8 ns ( ), making it suitable for high-speed data. Supply Voltage ( VCCcap V sub cap C cap C end-sub

): Typically operates between 4.5V and 5.5V (TTL compatible).

Isolation Voltage: Rated at 5300 Vrms, protecting sensitive control logic from high-voltage spikes. Power Consumption: Low current draw, with ICCcap I sub cap C cap C end-sub maximum around 1.2 mA. Common Mode Rejection (CMR): Very high immunity to noise ( >50is greater than 50 🛠️ Typical Pin Configuration

The device is commonly found in an 8-pin DIP or SO-8 package. While you should always verify with the official datasheet, a standard high-speed optocoupler pinout follows this logic:

Input Side: Usually Pins 2 (Anode) and 3 (Cathode) for the GaAsP LED. Output Side: Pins 5 (GND), 6 ( VOUTcap V sub cap O cap U cap T end-sub ), and 8 ( VCCcap V sub cap C cap C end-sub

Open Collector: Note that the output is often an open collector, meaning you will need a pull-up resistor to define the logic "High" state. 📋 Guide to Reading the Datasheet

When reviewing the HCPL-1458 documentation, pay attention to these critical sections: Scenario: Isolating a 24V PLC output to a 3

Absolute Maximum Ratings: Never exceed the forward current ( IFcap I sub cap F

) or peak output voltage, as this can permanently damage the internal LED or detector.

CTR (Current Transfer Ratio): Though this is a logic gate, understanding the ratio of output current to input current helps ensure your input signal is strong enough to trigger the output. Switching Characteristics: Look at the rise ( ) and fall (

) times if you are using this for PWM (Pulse Width Modulation) or high-frequency communication.

Typical Performance Curves: These graphs show how temperature affects speed and power consumption. 🚀 Common Applications

Microcontroller Interfacing: Safely connecting a 3.3V/5V MCU to high-voltage industrial equipment.

Digital Fieldbus Isolation: Used in CAN, RS-485, or Profibus circuits to prevent ground loops.

Switching Power Supplies: Providing feedback from the secondary side to the primary side without a direct wire connection. Operation: When PLC output is high (24V), LED