STFPC320 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

STFPC320

Front panel controller/driver with standby power management and real-time clock

STMicroelectronics 

STFPC320

17.5 Crystal electrical characteristics

Electrical characteristics

Table 18. Crystal electrical characteristics

Symbol

Parameter (1) (2)

Min Typ Max Units

fO

Resonant frequency

RS

Series resistance

32.768

kHz

35

40 (3)

kΩ

CL

Load capacitance

12.5

pF

1. Externally supplied. ST recommends the Citizen CFS-145 (1.5x5mm) and the KDS DT-38 (3x8mm) for

thru-hole, or the KDS DMX-26S(3.2x8mm) for surface-mount, tuning fork-type quartz crystals.

KDS can be contacted at kouhou@kdsj.co.jp or http://www.kdsj.co.jp

Citizen can be contacted at csd@citizen-americal.com or http://www.citizencrystal.com

2. Circuit board layout considerations for the 32.768KHz crystal of minimum trace lengths and isolation from

RF generating signals should be taken into account.

3. Guaranteed by design.

17.6

Oscillator characteristics

Table 19. Oscillator characteristics

Symbol

Parameter

Conditions

Min Typ Max Unit

VSTA Oscillator start voltage ≤10 seconds

1.5

tSTA Oscillator start time

VCC = 3.0 V

CL1

XIN

CL2

XOUT

IC-to-IC frequency

variation (1)

-10

V

1

s

25

pF

25

pF

+10 ppm

1. Reference value. TA = 25° C, VCC = 3.0V, CFM-145 (CL = 6pF, 32.768 KHz) manufactured by Citizen

71/78

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