ST ST7538Q, Application Note, Page: 42 / 56

Board description AN2744
42/56
5.7 Power supply
The ST7538Q dual channel reference design includes a specifically designed switching
mode power supply circuit, based on ST’s VIPer12AS-E device.
VIPer12AS-E is a smart power device with current mode PWM controller, startup circuit and
protections integrated in a monolithic chip using VIPower M0 technology. It includes a 27
Ω
Mosfet with 730 V breakdown voltage and a 400 mA peak drain current limitation. The
switching frequency is internally fixed to 60 kHz, in order to provide a good compromise
between EMI performances and magnetic parts dimensioning.
The internal control circuit offers the following benefits:
- large input voltage range on VDD pin accommodates changes in supply voltage
- automatic burst mode in low load condition
- overload and short circuit protection in hiccup mode
The power supply is designed in isolated flyback configuration with secondary regulation by
means of an optocoupler and a Zener diode, considering the requested output tolerance for
the specified application.
The main specifications are listed in Table 10
In the input stage, an EMI filter is implemented (C2, L2, C10, L3, C5) for both differential and
common mode noise, in order to fit the requested standard.
Table 8. 50-pin connector control signals
Pin n° Signal name Description Generated by
20 B_ID_PLM_1 Board ID for PLM Applications (MSB) PLC Board
28 B_ID_PLM_0 Board ID for PLM Applications (LSB) PLC Board
5 VDDF_FORCE Force µC digital level to VDDF PLC Board
Table 9. 50-pin connector power connections
Pin n° Signal name Description Generated by
2 PLM_10V 10V power supply PLC Board
4 VDD 3.3V/5V power supply ST7538Q
6 VDDF Digital power supply ST7538Q
22,34 GND Ground -
Table 10. SMPS specifications
Parameter Value
Input voltage range, V
IN
85-265 V
AC
Output voltage, V
OUT
10V±10%
Peak output current, I
OUT(MAX)
600 mA