ST7LITE20F2 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
ST7LITE20F2
STMicroelectronics
'ST7LITE20F2' PDF : 166 Pages View PDF
ST7LITE20F2 ST7LITE25F2 ST7LITE29F2
Supply, reset and clock management
Note:
When the Multi-oscillator is not used, PB4 is selected by default as external clock.
Crystal/ceramic oscillators
This family of oscillators has the advantage of producing a very accurate rate on the main
clock of the ST7. The selection within a list of 4 oscillators with different frequency ranges
has to be done by option byte in order to reduce consumption (refer to Section 15.1: Option
bytes for more details on the frequency ranges). In this mode of the multi-oscillator, the
resonator and the load capacitors have to be placed as close as possible to the oscillator
pins in order to minimize output distortion and startup stabilization time. The loading
capacitance values must be adjusted according to the selected oscillator.
These oscillators are not stopped during the RESET phase to avoid losing time in the
oscillator startup phase.
Internal RC oscillator
In this mode, the tunable 1% RC oscillator is used as main clock source. The two oscillator
pins have to be tied to ground.
Table 7. ST7 clock sources
Clock source
Hardware configuration
External clock
ST7
OSC1
OSC2
External
source
Crystal/ceramic resonators
ST7
OSC1
OSC2
CL1
CL2
Load
capacitors
Internal RC oscillator or
external clock on PB4
ST7
OSC1
OSC2
Doc ID 8349 Rev 5
37/166
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