VIPER26LN

Overview

The VIPER26LN is a high-voltage offline converter from the VIPer+ family, integrating an 800 V avalanche-rugged power MOSFET with PWM current mode control. It operates at a fixed switching frequency of 60 kHz and supports flyback, buck, and buck-boost topologies. The device features embedded HV startup, sense-FET, error amplifier, and oscillator with jitter for EMI reduction. It accepts universal AC input (90–264 V) and provides low standby power consumption (<30 mW). Protection includes thermal shutdown, delayed overload protection, and auto-restart on faults.

Feature Summary

• Integrates an 800 V avalanche-rugged power MOSFET with embedded high-voltage startup circuitry
• Features current mode PWM control with frequency jittering to minimize electromagnetic interference
• Includes built-in soft-start and hysteretic thermal shutdown for enhanced system reliability
• Provides automatic restart protection against overload, short-circuit, and feedback loop disconnection

Applications

• Non-isolated flyback power supplies
• Buck converter designs
• Buck-boost converter applications
• Universal input AC-DC adapters

Procurement Notes

Verify package type compatibility, as the VIPER26LN utilizes an 8-pin DIP through-hole configuration distinct from surface-mount variants in the same family. Confirm RoHS compliance status specific to the manufacturing batch, as historical records indicate variations in lead-free certification across different production runs. Ensure the supplier provides official datasheets matching the exact suffix to guarantee pinout and electrical parameter alignment.

Selection Notes

Select this component for designs requiring a single-chip solution for isolated or non-isolated converters with moderate power requirements. The integrated 800 V drain capability allows for reduced snubber circuit size and extended input voltage range. Consider the 60 kHz fixed frequency when designing magnetic components, noting that jittering helps lower EMI filter costs compared to strictly fixed-frequency alternatives without modulation.

Part Context

The VIPER26LN belongs to STMicroelectronics' VIPer+ family of smart high-voltage converters. This series combines a high-voltage power MOSFET with a PWM controller in a single IC, simplifying design by eliminating external bias windings and startup resistors. The LN variant specifically denotes the through-hole packaging option, catering to legacy board layouts or specific mechanical mounting requirements compared to the surface-mount LD version.

Replacement Considerations

• VIPER26LDTR

FAQ

What is the switching frequency of the VIPER26LN?

The device operates at a fixed switching frequency of 60 kHz with frequency jittering to reduce electromagnetic interference.

Does the VIPER26LN support isolated topologies?

While primarily documented for non-isolated flyback applications in demonstration boards, the VIPer+ family architecture supports flyback, buck, and buck-boost topologies, which can be configured for isolation depending on the transformer design.

How does the device handle fault conditions?

It features safe auto-restart after fault conditions, including thermal shutdown with hysteresis, delayed overload protection, and open-loop failure protection.