Overview
The VIPER27HD, produced by STMicroelectronics, is an off-line converter designed for high-voltage applications. It features an 800 V rugged power section, PWM control, and multiple protection mechanisms including over-current, overvoltage, and hysteretic thermal protection. The device is optimized for low EMI through frequency jittering and includes a high voltage start-up circuit, soft-start, and safe auto-restart after fault conditions. It is particularly suited for applications requiring low standby power consumption and compliance with energy saving regulations.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Drain-to-source (ground) voltage (VDRAIN) | 800 | V |
| Repetitive avalanche energy (EAV) | 5 | mJ |
| Repetitive avalanche current (IAR) | 1.5 | A |
| Pulse drain current (IDRAIN) | 3 | A |
| Operating frequency (VIPER27L) | 60 kHz | kHz |
| Operating frequency (VIPER27H) | 115 kHz | kHz |
| Standby power at 265 Vac | < 50 mW | mW |
| Drain-source on state resistance (RDS(on)) at 25 °C | 7 Ω | Ω |
| Drain-source on state resistance (RDS(on)) at 125 °C | 14 Ω | Ω |
| Operating junction temperature range (TJ) | -40 to 150 °C | °C |
| Storage temperature (TSTG) | -55 to 150 °C | °C |
Key Features
- 800 V avalanche rugged power section
- PWM operation with frequency jittering for low EMI
- Adjustable current limit set point
- Adjustable and accurate overvoltage protection
- On-board soft-start
- Safe auto-restart after a fault condition
- Hysteretic thermal shutdown
- Brown-out protection with hysteresis
- Burst mode operation for high performance in standby mode
Applications
- Auxiliary power supply for consumer and home equipment
- ATX auxiliary power supply
- Low to medium power AC-DC adapters
- Switch Mode Power Supplies (SMPS) for set-top boxes, DVD players and recorders, white goods
Q & A
- What is the maximum drain-to-source voltage of the VIPER27HD?
The maximum drain-to-source voltage is 800 V. - What are the operating frequencies for the VIPER27L and VIPER27H types?
The VIPER27L operates at 60 kHz, and the VIPER27H operates at 115 kHz. - What is the standby power consumption at 265 Vac?
The standby power consumption is less than 50 mW. - What is the purpose of the frequency jittering feature?
The frequency jittering feature reduces EMI filter costs. - How does the brown-out protection function?
The brown-out protection shuts down the device when the rectified input voltage is below the normal minimum level and restarts when the voltage exceeds the threshold. - What is the role of the soft-start feature?
The soft-start feature ensures a gradual increase in output voltage during startup to prevent inrush currents. - How does the overvoltage protection work?
The overvoltage protection monitors the output voltage and shuts down the converter if it exceeds the set threshold. - What is the significance of the hysteretic thermal shutdown?
The hysteretic thermal shutdown protects the device from overheating by shutting it down when the junction temperature exceeds a certain threshold. - Can the current limit set point be adjusted?
Yes, the current limit set point can be adjusted using an external resistor connected to the CONT pin. - What is the purpose of the burst mode operation?
The burst mode operation ensures high performance in standby mode and helps in meeting energy saving regulations.
