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, 07-21-2025, 08:10 AM

I am using STM32G475RE for a design I was asked to use HSI for this can anyone guide on this.Also I have to convert 31V to 24V supply for the design for which I have used L6982CDR, can anyone share how and what is CV CC mechanism in this.

Sniper2 , 07-22-2025, 07:31 PM

@sakshi3185_ CV aka sets the out voltage to what u set
CC constant current, IF load does draw more current then u set then this REDUCES Vout down to the point it is at the current you set

Sniper2 , 07-22-2025, 07:31 PM

ezample: 12V 1A

Sniper2 , 07-22-2025, 07:31 PM

if u conect a 10k load then voltage is 12V and current is 1.2maA

Sniper2 , 07-22-2025, 07:32 PM

if u use 100 OHM load then voltage is 12V and current is 0.12A

Sniper2 , 07-22-2025, 07:33 PM

if load is 10ohm then current will be 1.2A if it was 12V So then current is 1A and voltage is 10V

Sniper2 , 07-22-2025, 07:33 PM

there ask if u dont get it @sakshi3185_

QDrives , 07-23-2025, 08:41 PM

HSI is the High Speed Internal oscillator - one of the possible clock sources.

AviusAquila , 07-24-2025, 09:07 AM

HSI doesn't need you to anything on the hardware. The firmware will need to be written to startup HSI and select it as the clock source on your clock tree.

That said, even when I an working on a design that intends to use HSI, I generally leave the footprint for the crystal on the board, unless it's a highly space constrained board and there simply isn't enough space for it, or if those pins are needed for something else (which has never happened to me on anything larger than a 40 pin MCU)

, 07-31-2025, 10:36 AM

Thankyoi so much @AviusAquila @Sniper2 @wdr@QDrives
I will be studying on these points more.

, 08-29-2025, 08:15 AM

I have a schematic can anyone review my pcb and schemtaic.

Sniper2 , 08-29-2025, 02:10 PM

Post here @sakshi3185_

Robert Feranec , 08-31-2025, 02:47 AM

we will be doing reviews as a part of mebership, we are working on it now, coming soon https://youtu.be/I_hFv68CeCo

fleakour , 09-29-2025, 08:41 AM

STM32 HSI Quick Guide
The HSI (Internal High-Speed Clock) is used for fast startup and design simplification, as it doesn't require an external crystal.

Action: In CubeMX, set the System Clock Source to HSI (168MHz).

Note: The HSI's accuracy (±1%) is lower than an external crystal (HSE). High-precision applications (like USB) should still consider using HSE or calibrating the HSI via the PLL.

L6982CDR CV/CC Mechanism
The L6982 is a step-down converter that supports Constant Voltage / Constant Current (CV/CC) mode, often used for battery charging or LED driving.

CV (Constant Voltage): This is the default mode. The chip monitors the output via the FB pin and stabilizes the output voltage at the target level (24V).

CC (Constant Current): This is the current limiting mode. When the output current reaches the maximum value set via the CS pin, the chip automatically switches from CV to CC and reduces the voltage to ensure the current stays below the limit.

Core Concept: The chip automatically switches between CV and CC to ensure that either the voltage or the current limit is maintained, whichever is reached first.

Robert Feranec , 09-29-2025, 10:13 AM

maybe this can help you to select crystal: https://www.ndk.com/en/products/circuit/search/index.html?IC+Part+Number=STM32F4&IC+Part+Number_match=include&NDK+Spec+Number=&NDK+Spec+Number_match=include

Robert Feranec , 09-29-2025, 10:14 AM

change the mcu name