UM0240 datasheet(10/39 Pages) STMICROELECTRONICS

10 / 39 page

Power supply

UM0240

10/39

Figure 3.

Power supplies PCB area

2.1

Main power supply (VDD)

The main power supply system of Industrial Com Board consists of a DC-DC switching

converter based on step-down regulator L5973 from ST. The switching regulator is designed

to provide 5V (VDD) stabilized on the output with an input range 5V ÷ 35V and it can be

assembled in the two following configurations:

●

Buck: referring to Figure 1, the N-MOS M1 is removed and the diode D9 is replaced

with a short

●

Buck-Boost (not optimized)

2.2

MCU Flash programming (VPP)

A second power supply is implemented in the Industrial board, in order to provide the 12V

voltage supply required by the microcontroller during the In-Application Programming (IAP)

of the embedded Flash memory.

This power supply consists in a charge pump DC-DC regulator implemented by the ST

device ST662A, which is a step-up converter designed for the Flash memory programming.

Note that the charge pump converter is itself supplied by the switching regulator output VDD.

The device can be shut down through line PD3 of the microcontroller, in order to reduce

power consumption and noise when IAP is not needed.

UM0240 Arkusz danych(PDF) 10 Page - STMicroelectronics