VIPER22A PWM Controller IC – Offline SMPS Controller

The VIPER22A PWM Controller IC – Offline SMPS Controller is a high-voltage offline switching controller from STMicroelectronics, designed for low-power switch-mode power supply (SMPS) applications. Unlike a conventional PWM controller that requires a separate external power transistor, the VIPER22A integrates a current-mode PWM controller and a high-voltage power MOSFET on the same chip, simplifying the design of compact offline power supplies.

The device operates with a fixed 60kHz switching frequency and incorporates a high-voltage startup current source, allowing it to start directly from the high-voltage input side of an offline power supply. Its internal supply section supports a 9V to 38V VDD operating range, providing flexibility for auxiliary winding configurations commonly used in isolated flyback converters.

The VIPER22A uses current-mode control to regulate switching operation according to the feedback signal and primary-side current. This architecture is commonly used in flyback-based SMPS designs for applications where compact size, efficient power conversion, and integrated protection functions are required.

The IC incorporates several protection mechanisms, including overcurrent, overtemperature, and overvoltage protection with automatic restart. It also provides auxiliary undervoltage lockout with hysteresis and automatic burst-mode operation under light-load conditions, helping reduce switching activity when the load demand is low.

The VIPER22A is available in DIP-8 and SO-8 package variants, making it suitable for both through-hole and surface-mount PCB designs. Depending on the input range, package, thermal design, and converter topology, the device can be used in low-power offline supplies. The original device documentation lists typical power capabilities of up to approximately 20W for the DIP-8 version under certain mains conditions, with lower capability for wide-input applications and SO-8 versions. Actual output power depends on the complete SMPS design and thermal conditions.

Typical applications include battery charger adapters, standby power supplies, auxiliary supplies for motor control, TV and monitor standby circuits, and other low-power offline SMPS designs.

Features

• Integrated current-mode PWM controller and high-voltage power MOSFET

• Fixed 60kHz switching frequency

• Wide 9V–38V VDD supply range

• High-voltage startup current source

• Current-mode control architecture

• Auxiliary undervoltage lockout with hysteresis

• Automatic burst mode at low load

• Overcurrent protection

• Overvoltage protection

• Overtemperature protection

• Automatic restart after protection events

• Suitable for low-power offline SMPS designs

• Available in DIP-8 and SO-8 packages

Specifications

• Brand: STMicroelectronics

• Part Number: VIPER22A

• Product Type: Offline SMPS Primary Switcher / PWM Controller

• Controller Type: Current-Mode PWM

• Integrated Power Device: High-Voltage Power MOSFET

• Switching Frequency: 60kHz

• VDD Operating Range: 9V–38V

• Maximum Switching Drain-Source Voltage: Up to 730V

• Package Options: DIP-8 / SO-8

• Startup: High-Voltage Integrated Startup Source

• Protection: Overcurrent, overvoltage, overtemperature

• Protection Mode: Automatic Restart / Hiccup Operation

• Applications: Offline SMPS, adapters, standby supplies, auxiliary power supplies

Applications

• Offline SMPS power supplies

• AC-DC flyback converters

• Battery charger adapters

• Standby power supplies

• TV and monitor standby circuits

• Auxiliary motor-control supplies

• Low-power embedded power supplies

• Consumer electronics power supplies

• Industrial control power supplies

• Compact AC-DC converter designs