ST72682 datasheet(22/36 Pages) STMICROELECTRONICS

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Electrical characteristics

ST72682

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7.5

Clock and timing characteristics

Subject to general operating conditions for VDD33, fOSC, and TA.

7.5.1

Crystal oscillator

The Device internal clock is supplied from a crystal oscillator. All the information given in this

paragraph are based on characterization results with specified typical external components.

In the application 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

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

Figure 7.

Typical application with a crystal

Depending on the crystal power dissipation, a serial resistor RsOscout may be added. Refer to the crystal

manufacturer for more details.

Table 14.

Clock characteristics

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

fOSC

Oscillator frequency

MHz

CKACC

Total crystal oscillator

accuracy

Absolute value +

temperature + aging

±60

ppm

OSC

Crystal oscillator duty cycle(1)

The crystal oscillator duty cycle has to be adjusted through the two CL capacitors. Refer to the crystal

manufacturer for more details.

Table 15.

Typical CL and RS values by crystal

Supplier

Typical Crystal

CL (pF)

RSOSCOUT

(

Ω)

NDK

AT51 or AT41

560

OSCOUT

OSCIN

Device

CRYSTAL

RSOSCOUT

(1)

VDDA

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