原标题：ST VIPER38LE 12V 1.25A 15W反激转换器解决方案

　　ST公司的VIPER38LE是集成了800V功率MOSFET和采用PWM电流模式控制的高压转换器,在轻负载时工作在突发模式有非常低的功耗,因此能满足更严格的节能标准,230Vac时的无负载功耗30mW,两种工作频率60 kHz或115 kHz,主要用在消费类电子和家用电器辅助电源,电表和数据集中器的电源和适配器.本文介绍了VIPER38LE主要特性,框图和典型的反激应用电路,以及评估板STEVAL-ISA153V1主要特性,电路图和材料清单.

　　The device is a high-voltage converter that smartly integrates an 800 V rugged power MOSFET with PWM current-mode control. This IC is capable of meeting more stringent energysaving standards as it has very low consumption and operates in burst mode under light load.

　　The device features an adjustable extra power timer (EPT) that enables the IC to sustain overload conditions for a few seconds. The integrated HV startup, sense FET and oscillator with jitter allow the advantage of using minimal components in the application.

　　The device features high-level protections like dual-level OCP, output overvoltage, short-circuit, and thermal shutdown with hysteresis. After the removal of a fault condition, the IC is automatically restarted.

　　VIPER38LE主要特性:

　　800 V avalanche-rugged power MOSFET with embedded HV startup and sense FET

　　PWM current-mode controller

　　OCP with selectable threshold (IDlim) and 2nd OCP with higher value (IDMAX) to protect the IC from transformer saturation or short-circuit of the secondary diode

　　30 mW no-load consumption at 230 Vac

　　Two operating frequencies: – 60 kHz or 115 kHz

　　Jittered frequency reduces the EMC

　　Extra power timer (EPT) blanks the overload current for few seconds

　　Output overvoltage protection with tight tolerance and digital noise filter

　　Soft-start reduces the stress during startup and increases IC lifetime

　　Automatic restart after a fault condition

　　Thermal shutdown increases system reliability and IC lifetime

　　VIPER38LE应用:

　　Auxiliary power supply for consumer and home equipment

　　Power supply for energy meters and data concentrators

　　Adapters

　　图1. VIPER38LE框图

　　图2. VIPER38LE基本反激应用电路图

　　图3. VIPER38LE全特性反激应用电路图

　　评估板STEVAL-ISA153V1

　　The STEVAL-ISA153V1 product evaluation board implements a 12 V/1.25 A, 15 W (20 W peak) isolated flyback wide-range mains developed for general-purpose applications.The core of the application is the VIPER38LE, the latest offline converter from the VIPerPlus family.

　　The device is a high-voltage converter that smartly integrates an 800 V rugged power MOSFET with PWM current-mode control. The device features an adjustable extra power timer (EPT) that enables the IC to sustain overload conditions for a few seconds.

　　The main characteristics of the evaluation board are its small size and minimal BOM, high efficiency and low standby consumption.

　　Extremely low consumption under no-load conditions is ensured thanks to burst mode operation which reduces the average switching frequency and minimizes all frequency-related losses.

　　The VIPER38LE operates at a fixed 60 kHz frequency. Frequency jittering is implemented, which helps the application meet electromagnetic disturbance standards.

　　The IC includes high-level protection features such as dual-level OCP, output overvoltage, short-circuit, and thermal shutdown with hysteresis. After removal of a fault condition, the IC is automatically restarted.

　　评估板STEVAL-ISA153V1主要特性:

　　Universal input mains range: 90 – 265 VAC frequency: 50 - 60 Hz

　　Output voltage/current: 12 V/1.25 A (1.65 A peak)

　　Very compact size

　　Standby mains consumption: lower than 30 mW at 230 VAC

　　Minimum active mode efficiency: 81.55%

　　Minimum active mode at 10% load efficiency: 71.55%

　　EMI: in accordance with EN55022-Class-B

　　RoHS compliant

　　图4. 评估板STEVAL-ISA153V1外形图

　　图5. 评估板STEVAL-ISA153V1电路图

　　评估板STEVAL-ISA153V1材料清单: