ATX switching power supply technology using PS223 design - Power Circuit - Circuit Diagram

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Switching power supply is based on safety and reliability. High-performance high-power ATX power supply design uses power management monitoring chip to achieve anti-surge soft start and protection against overvoltage, undervoltage, overheat, overcurrent, short circuit and overtemperature. .

Switching Power Supply (SPS) utilizes modern power electronics technology to be widely used in electronic devices, such as various terminal devices and communication devices, which are small, energy-saving, lightweight, and highly efficient.

1 ATX power supply overview and power management monitoring protection

Intel's high-power (350-900 W) ATX power specification version is ATXl2V 2.2, +12 V uses dual output, one of which +12 V (A) is dedicated to the CPU, and the other +12 V (B ) Power is supplied to other devices, and the connector output to the motherboard is 24 pins to output two groups of +12 V.

The high-performance switching power supply is designed as an active power factor correction (PFC), using a CM6800G integrated PFC/PWM controller such as Champion to provide PFC and PWM power stage circuit integration control for power supplies, using power supplies such as PS223. The management monitor chip provides multiple protections such as overvoltage, overcurrent, overpower, low voltage and short circuit. Temperature is the most important factor affecting the reliability of power supply equipment. According to the analysis of relevant data, overheating will cause damage to the power device, and an overheat protection circuit needs to be provided. The short circuit protection (SCP) and overload protection (OPP) in the protection design are ATXl2V mandatory standards, which are triggered to protect the power supply when the short circuit and the total load of each road are overloaded; the overcurrent protection (OCP) prevents the output of the power supply from being overloaded; (OTP) prevents internal overheating of the power supply; overvoltage/undervoltage protection (OVP/UVP) is used to trigger when the output voltage exceeds/below the standard value of 20~25%. If the power supply is abnormal, the output will be cut off immediately. All have no output. At the moment when the power is turned on, the fan stops and the power is protected.



Figure 1 is a block diagram of the switching power supply conversion process. The switching power supply conversion process is AC input → EMI filter circuit → rectifier circuit → power factor correction circuit → power stage primary side (high voltage side) switching circuit is converted into pulse flow → main transformer → power level two Secondary side (low voltage side) rectifier circuit → voltage adjustment circuit (DC-DC converter circuit) → filter circuit → power management monitoring → output.

2 PS223 features

The PS223 from SiTI is a power management monitoring chip designed for high-performance, high-power switching power supplies. It has control, PG generation and stable +3.3 V, +5 V, +12 V(A), +12 V ( B) Three kinds of voltages, realize UVP (low voltage protection), OVP (overvoltage protection), OCP (overcurrent protection), SCP (short circuit protection) of each output, and provide a control input with self-recovery function. It can be used as OTP (over temperature protection) or -12 V UVP (low voltage protection). When the on-chip set value is exceeded, the control circuit will be closed and locked, and the power supply output will be stopped. It can be restarted after the fault is removed. The internal design has overload protection and lightning protection to ensure stable operation of the entire power supply.

2.1 PS223 main performance indicators

1) Overvoltage/undervoltage protection and locking; 2) Overcurrent protection and locking; 3) Fault protection, shutdown output; 4) Power good output and signal protection; 5) Built-in 300 ms power good output delay; 6) 75 Ms low voltage / over voltage delay protection; 7) 38 ms anti-shock protection; 8) 73μs anti-noise protection; 9) wide supply voltage range (90 ~ 270 V); lO) AC power off special protection.

2.2 PS223 pin function description

The PS223 is available in a 16-pin DIP package with the following functions: PGI is the MAIN POWER signal output; VSS is the ground; OVP/UVP/OCP protection signal output; REMOTE CONTROL output for switching SPS; ISl2A It is a 12 V (A) OCP comparator V+ input with built-in Sink current source for OCP protection operating point adjustment; RI is used to generate OCP current source through grounding resistor (R1: 20-80 kΩ); ISl2B is used for 12 V(B)OCP comparator V+ input, built-in Sink current source for OCP protection operating point adjustment; VSl2B for 12 V(B)OCP comparator V-input, 12 V(B)OVP/UVP detection OTP is an additional protection function for OTP (temperature abnormality protection); IS5 is 5 V OCP comparator V+ input, built-in Sink current source for OCP protection operating point adjustment; IS33 is 3.3 V OCP comparator V+ Input, built-in Sink current source for OCP protection operating point adjustment; VSl2A is 12 V OCP comparator V-input, 12 V OVP/UVP detection: VS33 is 3.3 V OCP comparator V-input, 3.3 V OVP/UVP detection: VS5 is 5 V OCP comparator V-input, 5 V OVP/UVP detection; VCC is working power 3.8 ~ 15 V; PGO is used for PW-OK, electricity

2.3 Description of main control signals

The ATX switching power supply relies on a combination of PGI (+5 VSB) and control signals to turn the power on and off.

PGI (+5 VSB) is the power supply for the host system in the ATX standby state. It is used for wake-up WOL (Wake-up On Lan) and boot circuit, USB interface, etc., as well as open and close automatic management of working power, in standby and subject In the controlled start state, the output voltage is 5 V high level, and the purple wire is used to lead out from the ATX plug 9 pin.

For the host to turn off the power or the network computer remote wake-up power control signal, when pressing the POWER switch of the host panel or the network wake-up remote power-on, after the controlled start, the PSON is grounded by the electronic switch of the motherboard, when the signal level of the port is greater than 1 At .8 V, the main power is off; when the signal level is below 1.8 V, the main power is on. Use the green wire to input from the 14 pin of the ATX plug.

PGO (PW_OK) is an output signal for the motherboard to detect the power supply. When the output is above 2 V, the power supply is normal. When the output is below 1 V, the power supply is faulty. Normally, the standby state is zero level, and the controlled startup voltage output is stable to 5 V high level. The gray line is taken from the 8 pin of the ATX plug. This signal is one of the main criteria for judging whether the power supply life and quality are qualified.

It is UVP (low voltage protection), OVP (overvoltage protection), OCP (overcurrent protection) protection control signal output.

3 application circuit and design

3.1 PS223 Typical Application Circuit

The typical application circuit of PS223 is shown in Figure 2.