ST72521AR9TC View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST72521AR9TC

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

STMicroelectronics 

ST72521M/R/AR

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

Max

Unit

fOSC

Oscillator Frequency 1)

LP: Low power oscillator

MP: Medium power oscillator

MS: Medium speed oscillator

HS: High speed oscillator

1

2

>2

>4

4

8

MHz

>8

16

RF

Feedback resistor

20

40

kΩ

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

56

MP oscillator 22

MS oscillator 18

46

33

pF

HS oscillator 15

33

Symbol

Parameter

i2

OSC2 driving current

Conditions

Typ Max

Unit

VDD=5V

VIN=VSS

LP oscillator 80

150

MP oscillator 160

250

MS oscillator 310

460

µA

HS oscillator 610

910

Figure 84. 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.

165/199

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