ST7LCR

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4.4.3

Crystal resonator oscillators

The ST7 internal clock is supplied with one Crystal resonator oscillator. 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 resonator manufacturer for more details (frequency,

package, accuracy...).

Table 12.

Crystal resonator characteristics

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

MP: Medium power oscillator

4

MHz

Feedback resistor

90

150

k

Ω

Recommended load

capacitances versus

equivalent serial resistance

of the crystal resonator

See Table 14

(MP oscillator)

22

56

pF

OSCOUT driving current

(MP oscillator)

1.5

3.5

mA

1.

Contact crystal resonator manufacturer for more details.

Table 13.

Typical crystal resonator characteristics

Oscillator

Reference

Freq.

(pF)

(pF)

MP

JAUCH

SS3-400-30-

30/30

4MHz

∆f

33

33

7~10

1.

Resonator characteristics given by the crystal resonator manufacturer.

2.

Table 14.

Recommended values for 4 MHz crystal resonator

Symbol

Min

Typ

Max

(1)

20

Ω

25

Ω

70

Ω

56 pF

47 pF

22 pF

56 pF

47 pF

22 pF

1.