What Optocouplers Are Good For UPS?


Uninterruptible Power Supplies (UPS) are essential devices that provide continuous power to critical equipment, ensuring uninterrupted operation during power outages or fluctuations. One crucial component used in UPS systems is optocouplers. Optocouplers, such as the MPH-341 from Melexis Technologies in Taiwan, play a significant role in driving inverters and motor control inverters. In this post, we will explore the application of optocouplers in UPS systems and discuss the features and benefits of the MPH-341 series.

Understanding UPS and Optocouplers:

UPS systems consist of energy storage units connected to the main unit, typically lead-acid batteries. These systems employ various circuit modules, including inverters, to convert DC power from the batteries into AC power for connected devices. The primary purpose of a UPS is to provide a stable and uninterrupted power supply to equipment like computers, computer networks, and other power electronic devices, protecting them from data loss, communication interruptions, or loss of control.

Optocouplers, also known as optoisolators, are devices that combine an optically coupled emitter (usually an LED) and receiver (often a phototransistor or photodiode). They enable electrical isolation between two circuits while allowing the transfer of signals through optical transmission. Optocouplers are ideal isolation components in electronic and electrical products, including UPS systems, providing high-voltage isolation capabilities.

MPH-341 Optocoupler for UPS:

The MPH-341 series optocoupler from Melexis Technologies is specifically designed for driving inverters and motor control inverters in UPS systems. It features an aluminum gallium arsenide LED optically coupled to an integrated circuit with power output stages. The optocoupler delivers a peak output current of 3.0A, capable of directly driving most IGBTs rated up to 1200V/200A. For IGBTs with higher ratings, the MPH-341 series can drive the discrete power stages that control the IGBT gate. The optocoupler operates within a temperature range of -40°C to +110°C, ensuring reliable performance under various conditions.

Key Features of the MPH-341 Optocoupler:

Peak output current of 3.0A: The optocoupler provides high current capability, enabling efficient driving of IGBTs in UPS systems.

Rail-to-rail output voltage: The optocoupler ensures that the output voltage covers the full range of the power supply, maximizing the utilization of the IGBTs.

Large propagation delay time of 100ns: The optocoupler offers a delay in signal transmission, which is important for maintaining synchronization and preventing timing issues in UPS applications.

Undervoltage Lockout (UVLO) with hysteresis: The optocoupler incorporates protection against low voltage conditions, ensuring reliable operation during power fluctuations.

Wide operating range: The optocoupler operates within a 15V to 30V (Vcc) voltage range, accommodating various UPS system designs.

Guaranteed performance over a temperature range of -40°C to +110°C: The optocoupler’s performance is ensured across a wide temperature range, making it suitable for UPS applications in different environments.


Optocouplers play a critical role in the reliable operation of Uninterruptible Power Supplies (UPS). The MPH-341 series optocoupler from Melexis Technologies offers exceptional features and performance for driving inverters and motor control inverters in UPS systems. With its high peak output current, rail-to-rail voltage capability, and wide operating temperature range, the MPH-341 optocoupler provides reliable and efficient power transfer, ensuring uninterrupted power supply to critical equipment. 

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