STM32 HSE HSI selection

[LLi.7]

Hi :

we notice both HSE or HSI could be used to supply system clock.

what is the difference between these two options? and which one should we use in our product?

and, for the power consumption, if we connect external crystal, then choose HSE mode, will it use more power?

[Shirley.Ye]

• HSI (High-speed internal oscillator) clock: ~ 8, 16, 32 or 64 MHz

• HSE (High-speed external oscillator) clock: 4 to 48 MHz

The HSI frequency, even with frequency calibration, is less accurate than an external crystal

oscillator or ceramic resonator

[LLi.7]

Hi Shirley:

thx for the information.

what about power consumption? as our device is powered by battery, if HSE is used, will it consume considerable energy? is there any document compare the power difference?

for example: HSI 16MHz power consumption vs HSE 16MHz power consumption

[Uwe Bonnes]

Have a close look at the datasheet and related application needs. Consumption number for many things are given.

[TDK]

If you're asking for specific information, consider including your specific part number. There are over 3000 STM32 parts, we don't know what you're using.

In general, HSE uses more energy than HSI.

[LLi.7]

thx for the reminder, we are using STM32L072CZ :grinning_face:

[Paul1]

Careful: Are you doing any data communication?

These typically need accurate clocks: USB, UART, CAN, LIN, OneWire, etc.

I2C and SPI don't as they provide the clock with the data.

Paul