ST ISA007V1 User Manual

查询STEVAL-ISA007V1供应商

High power 3-phase auxiliary power supply evaluation board

Based on L5991 and ESBT STC08DE150HV

Features

■ 3-phase 150W auxiliary dual output SMPS

■ Input: 400Vac +/- 20%

■ Output voltage 1: 24V, 6.25A @ 90kHz

■ Output voltage 2: 5V, 0.075A @ 90kHz

■ Auxiliary output voltage: 15V, 0.01A

■ Maximum output power : 150W

■ Efficiency > 85%

■ Switching frequency > 90kHz

■ Stand-by switching frequency > 35kHz

■ Feedback: secondary regulation

STEVAL-ISA007V1

Preliminary Data

STEVAL-ISA007V1

Description

Auxiliary SMPS is particularly affected since it is
the entry point for all the biasing of control ICs and
cooling system powering. Standardization
towards "universal input" is reflected in more
stressful conditions for the power transistor used
as the main switch both in terms of blocking
voltage or current capability. Since almost all
auxiliary power supplies are based on fly-back
converters, the need for a blocking voltage as high
as 1500V and over, coupled with high switching
frequency operations, make the ESBTs the
perfect choice for such power supplies. The
STC08DE150HV, in conjunction with the PWM
L5991, perfectly fulfills the requirements and
brings high efficiency to the system

ST components

■ STC08DE150HV Emitter Switched Bipolar

Transistor, 5A, 1500V, TO247-4L HV leads

■ L5991A PWM SMPS controller, DIP-16

■ TL431AI shunt reference, 2.5V, 1mA...100mA,

TO-91

■ PN2222A small signal bipolar transistor, NPN,

40V, 0.6A, 330mW,TO-92

■ STTH102 high voltage ultrafast diode, 200V,

1A, DO-41

■ 1.5KE400A transil, 400V, 1.5kW, DO-201

■ STTH108 high voltage ultrafast diode, 800V,

1A, DO-41

■ STTH3002CT high efficiency ultrafast diode,

200V, 30A, TO-220AC

June 2007 Rev 2 1/5

This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to
change without notice.

www.st.com

5

Reference design general description STEVAL-ISA007V1

1 Reference design general description

A dedicated reference design with ESBT has been developed, featuring the high power wide
input range requirement of a highly demanding industrial market.

The maximum output power is 150W. Generally speaking, the necessity to handle both high
output power and wide input voltage leads to the design of a fly-back stage working in mixed
operation mode: continuous and discontinuous:

The continuous current mode introduces a right half plan zero in the loop-transfer function
which makes the feedback stabilization difficult. At the input voltage range, and after a brief
description of the differences between continuous and discontinuous mode, it will soon be
clear that it is very difficult and inconvenient to design a fly-back converter working in
discontinuous mode. Finally, referring to the power spec of our demo, it is clear that
discontinuous mode cannot be used because it would determine a very high primary and
secondary peak current with a higher cost of all the main components involved: power
transistor, secondary diode and output capacitor.

Thanks to the adoption of the PWM L5991, the converter is able to operate in mixed mode.
For higher power levels with a switching frequency close to 90kHz, the converter operates in
Continuous Current Mode (CCM), while in stand-by and for power levels lower than 25W,
the converter works in Discontinuous Current Mode (DCM) at a switching frequency of
about 35kHz.

2/5