The RGB power LED feature is designed with the following elements:
•
SML-LX5050SIUPGUBC RGB High Brightness LED from LUMEX
•
LPB-S01110101S squared pipe bar and diffuser from LUMEX
•
3 step-down inverted buck converters, each one driving a color LED (red, green or blue)
•
4-way joystick plus selection key managing the color selection and luminous intensity dimming
•
4 user LEDs as status indicators
The joystick and user LEDs give full control of the RGB power LED function selection and management. For more
details about the RGB LED function management, refer to the application note
High-brightness RGB LED control
using the B-G474E-DPOW1 Discovery kit
(AN5345).
Figure 19.
RGB power LED function
BUCK_BLUE_LED
LD1 RGB power LED
and LPB1 diffuser
BUCK_GREEN_LED
BUCK_RED_LED
B2 Joystick
4 user LEDs
The inverted buck topology is used to reduce the number of components for this discrete application. Each
buck
‑
LED converter is controlled with an HRTimer as the DRIVE command and has a current regulation on a
SENSE comparator input.
The STM32G474RET6 microcontroller manages each color LED individually, which enables the following
features:
•
Single color LED or mixed color LED pattern selection, including white-colored LED.
•
Manual or automatic dimming for luminance selection.
By default, the 5 V general supply of the board is used as a power supply for the three buck
‑
LED converters. The
total current needed to run this function is quite low, about 250 mA for white color at its recommended maximum
luminance. Thus, any of the JP5 power sources can be used to demonstrate the RGB power LED.
In case the user wants to use any other power supply, it is possible to bring it on TP3 and disconnect R133.
13.5
Extension connector headers
Caution:
Before using the extension connector pin to control an external application, check that the PIOs to be used are
not already used in the design, otherwise permanent damage can occur. Every PIO of extension connector may
be used externally, providing it is isolated from the features integrated on the Discovery board. Serial resistors or
solder bridges are available to disconnect most of them (Refer to
Section 14.4 CN9 extension connector
Section 14.5 CN8 extension connector
Caution:
When the B-G474E-DPOW1 Discovery board is used in standalone, take care to put it on a non-conductive
material to avoid short circuits on all bottom side connectors or permanent damage can occur.
UM2577
Extension connector headers
UM2577
-
Rev 2
page 30/54
