ST72F324J6TCX 데이터 시트보기 (PDF) - STMicroelectronics

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ST72F324J6TCX

8-bit MCU for automotive, 3.8 to 5.5V operating range with 8 to 32 Kbyte Flash, 10-bit ADC, 4 timers, SPI, SCI

STMicroelectronics 

ST72324xx-Auto

Electrical characteristics

12.6.3

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 resonator 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 stabilization time. Refer to the crystal/ceramic resonator

manufacturer for more details (frequency, package, accuracy...).

Table 94. Crystal and ceramic resonator oscillators

Symbol

Parameter

Conditions

Min Typ Max Unit

) fOSC

ct(s RF

rodu CL1

CL2

bsolete P i2

Oscillator frequency(1)

Feedback resistor(2)

LP: low power oscillator

MP: medium power oscillator

MS: medium speed oscillator

HS: high speed oscillator

Recommended load capacitance

versus equivalent serial

resistance of the crystal or

ceramic resonator (RS)(3)

OSC2 driving current

RS = 200Ω LP oscillator

RS = 200Ω MP oscillator

RS = 200Ω MS oscillator

RS = 100Ω HS oscillator

VDD = 5V, VIN = VSS

LP oscillator

MP oscillator

MS oscillator

HS oscillator

1

2

>2

>4

4

8

MHz

>8

16

20

40 kΩ

22

56

22

18

46

33

pF

15

33

80 150

160 250 µA

310 460

610 910

- O 1. The oscillator selection can be optimized in terms of supply current using a high quality resonator with a

) small RS value. Refer to crystal/ceramic resonator manufacturer for more details.

t(s 2. Data based on characterization results, not tested in production. The relatively low value of the RF resistor,

offers a good protection against issues resulting from use in a humid environment, due to the induced

c leakage and the bias condition change. However, it is recommended to take this point into account if the

u microcontroller is used in tough humidity conditions.

d 3. For CL1 and CL2 it is recommended to use high-quality ceramic capacitors in the 5pF to 25pF range (typ.)

ro designed for high-frequency applications and selected to match the requirements of the crystal or

resonator. CL1 and CL2, are usually the same size. The crystal manufacturer typically specifies a load

P capacitance which is the series combination of CL1 and CL2. PCB and MCU pin capacitance must be

included when sizing CL1 and CL2 (10 pF can be used as a rough estimate of the combined pin and board

tecapacitance).

ObsoleFigure 68. Typical application with a crystal or ceramic resonator

When resonator with

integrated capacitors

i2

CL1

OSC1

fOSC

Resonator

RF

CL2

OSC2

ST72XXX

Doc ID 13841 Rev 1

155/193

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