ST72F521R9TC View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST72F521R9TC

8-BIT MCU WITH NESTED INTERRUPTS, FLASH, 10-BIT ADC, FIVE TIMERS, SPI, SCI, I2C, CAN INTERFACE

STMicroelectronics 

ST72521

CLOCK AND TIMING CHARACTERISTICS (Cont’d)

12.5.3 Crystal and Ceramic Resonator Oscillators

The ST7 internal clock can be supplied with four

different Crystal/Ceramic resonator oscillators. All

the information given in this paragraph are based

on characterization results with specified typical

external components. In the application, the reso-

nator and the load capacitors have to be placed as

close as possible to the oscillator pins in order to

minimize output distortion and start-up stabiliza-

tion time. Refer to the crystal/ceramic resonator

manufacturer for more details (frequency, pack-

age, accuracy...).

Symbol

Parameter

Conditions

Min

fOSC

Oscillator Frequency 1)

LP: Low power oscillator

1

MP: Medium power oscillator

>2

MS: Medium speed oscillator

>4

HS: High speed oscillator

>8

RF

Feedback resistor

20

CL1

CL2

Recommended load capacitance ver-

sus equivalent serial resistance of the

crystal or ceramic resonator (RS)

RS=200Ω

RS=200Ω

RS=200Ω

RS=100Ω

LP oscillator 22

MP oscillator 22

MS oscillator 18

HS oscillator 15

Max

2

4

8

16

40

56

46

33

33

Unit

MHz

kΩ

pF

Symbol

Parameter

i2

OSC2 driving current

Conditions

Typ

VDD=5V

VIN=VSS

LP oscillator 80

MP oscillator 160

MS oscillator 310

HS oscillator 610

Max

150

250

460

910

Unit

µA

Figure 90. Typical Application with a Crystal or Ceramic Resonator

WHEN RESONATOR WITH

INTEGRATED CAPACITORS

CL1

OSC1

i2

fOSC

RESONATOR

RF

CL2

OSC2

ST72XXX

Notes:

1. The oscillator selection can be optimized in terms of supply current using an high quality resonator with small RS value.

Refer to crystal/ceramic resonator manufacturer for more details.

173/211

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