Hardware Introduction
2-14
from INFINEON company, which basic parameter is 650V/6.2A. The +5V output is the main
feedback output of the FORWARD converter, +13.5V and +12V are adjusted by the magnetic
amplifier, and +24V is stabilized linearly by LM317.
HV is output from the BOOST converter, which uses the voltage control chip TL594 from
ONSEMI company. HV is controlled by 0-4V analog input signal and varies linearly between
30V and 140V with the variation of control signal.
+3.3V is output from the BUCK converter which is based on synchronous rectification.
EL7566 from INTERSIL company works as the controller, which integrates all control and
protection circuits and switch tube. Its rated output current is 6Amp and its conversion
efficiency can reach 96% at most.
+2.5V and +1.5V are the outputs of +3.3V after linear voltage-stabilizing, which is performed
by IRF7401 MOS from IR company and feedback control circuit. The MOS works at the
amplification area to realize linear stabilizing of low voltage.
-5V is obtained from +5V through BUCK-BOOST converter, which uses the control chip
TPS6755 from TI company. The chip, integrating MOS, produces negative voltage output
along with external inductors, capacitors and diodes and have current limit protection for
switch tube.
2.3.4. Protection Circuit
The power supply board has following protection functions: PFC output overvoltage protection,
output overvoltage protection, overtemperature protection, +5V/+12V/+13.5V/-5V/HV output
overvoltage/overcurrent/short-circuit protection, and other short-circuit protections.
1. When PFC output overvoltage protection, overtemperature protection or +5V output
overvoltage/overcurrent/short-circuit protection works, the whole power supply board stops all
outputs and locks. The board does not work until the system recovers from the failure and
restarts.
2. When +13.5V output overvoltage/overcurrent/short-circuit protection works, +13.5V and HV
outputs stop and keep locking. +13.5V and HV cannot be output until the failure is removed
and the +13.5V/+12V output load is disconnected.
3. When +12V output overvoltage/overcurrent/short-circuit protection works, the output stops
and keeps locking. The +12V cannot be output until the failure is removed and the
+13.5V/+12V output load is disconnected.
4. When +3.3V short-circuit protection works, +3.3V and HV outputs stop. They can recover
automatically after the failure is removed.
5. When -5V overcurrent/short-circuit protection works, -5V output stops. When -5V
overvoltage protection works, the output stabilizes at some voltage (>-7V) exceeding the rated
voltage, not affecting other outputs, and can recover automatically after the failure is removed.
6. When HV overvoltage/overcurrent/short-circuit protection or +1.5V/+2.5V
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