A1458 Optocoupler Datasheet -

Dark current doubles approximately every 10°C. At high temperatures, it can become significant, so ensure your pull-up resistor and logic threshold account for this. Current Transfer Ratio (CTR) CTR is the gain of an optocoupler: (I_C / I_F) * 100%. The A1458 offers multiple rank options:

Introduction In the world of electronics, isolation is paramount. Whether you are designing a switch-mode power supply (SMPS), a microcontroller interface for industrial machinery, or a safety system for a medical device, the optocoupler (also known as an opto-isolator) is a critical component. Among the myriad of options available, the A1458 optocoupler has gained recognition for its balance of speed, current transfer ratio (CTR), and isolation voltage. a1458 optocoupler datasheet

| 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 | Dark current doubles approximately every 10°C

| Pin Number | Name | Description | |------------|-------------|------------------------------------| | 1 | Anode (A) | Positive terminal of the IR LED | | 2 | Cathode (C) | Negative terminal of the IR LED | | 3 | Emitter (E) | Output phototransistor emitter | | 4 | Collector (C)| Output phototransistor collector | The A1458 offers multiple rank options: Introduction In

| Parameter | Symbol | Conditions | Typ | Max | Unit | |-----------|--------|-------------|-----|-----|------| | Rise Time | t_r | V_CE = 2V, I_C = 2mA, R_L = 100Ω | 4 | 18 | μs | | Fall Time | t_f | Same as above | 3 | 18 | μs | | Turn-On Time | t_on | I_F = 10 mA to I_C = 2mA | 5 | 20 | μs | | Turn-Off Time | t_off | Same | 4 | 20 | μs |

| Rank | CTR Min (%) | CTR Max (%) | Conditions | |------|-------------|-------------|-------------| | A | 50 | 150 | I_F = 5 mA, V_CE = 5V, Ta=25°C | | B | 80 | 240 | I_F = 5 mA, V_CE = 5V, Ta=25°C | | C | 130 | 400 | I_F = 5 mA, V_CE = 5V, Ta=25°C | | D | 200 | 600 | I_F = 5 mA, V_CE = 5V, Ta=25°C |

Switching speed is heavily dependent on the load resistor (R_L). A smaller R_L reduces the time constant (R_L * C_CE) but also reduces output voltage swing. For higher speeds (>100 kHz), consider a phototransistor optocoupler with a base access pin or a digital optocoupler. Part 6: Isolation Characteristics The isolation barrier is the primary reason to use the A1458. The datasheet provides the following isolation parameters: