AN2633 datasheet(7/48 Pages) STMICROELECTRONICS

Part #	AN2633

Description	STR91xFA low power management and power consumption

PDF	48 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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7 / 48 page

AN2633

Power supply and clocks

7/48

the main oscillator source at any time and turn off the PLL for low-power operation. The

PLL is always turned off in Sleep mode.

●

The fOSC input clock has a frequency of 4 to 25 MHz. This input clock can be sourced

by an external crystal connected to STR91xFA pins X1_CPU and X2_CPU or an

external oscillator device connected to X1_CPU.

●

RTC is a 32.768 kHz external crystal which can be connected to X1_RTC and X2_RTC

or an external oscillator connected to pin X1_RTC to constantly run the real-time clock

unit. You can program the application to run from this slow clock when you want to save

power.

You can choose the source to match the CPU performance and the power management

requirements of your application. Transitions from one clock to another are glitch-free and

do not disrupt any on-going activities

AN2633 Datasheet(PDF) 7 Page - STMicroelectronics