M41T66 datasheet(26/33 Pages) STMICROELECTRONICS

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DC and AC parameters

M41T66

26/33

Table 12.

Oscillator characteristics

Figure 16.

Bus timing requirements sequence

Table 11.

Crystal electrical characteristics

Sym

Parameter(1)(2)

Externally supplied if using the QFN16 package. STMicroelectronics recommends the Citizen CFS-145

(1.5 x 5 mm) and the KDS DT-38 (3 x 8 mm) for thru-hole, or the KDS DMX-26S

(3.2 x 8 mm) for surface-mount, tuning fork-type quartz crystals. KDS can be contacted at

http://www.kds.info/index_en.htm. Citizen can be contacted at http://www.citizencrystal.com.

Load capacitors are integrated within the M41T66. Circuit board layout considerations for the 32.768 kHz

crystal of minimum trace lengths and isolation from RF generating signals should be taken into account.

Min

Typ

Max

Units

Resonant frequency

32.768

kHz

Series resistance (TA = –40 to 70°C)

75(3)(4)

Guaranteed by design.

RS (max) = 65 kΩ for TA = –40 to 85°C and oscillator startup at 1.7 V.

Load capacitance

7-12.5(5)

External capactors must be added to achieve better clock accuracy.

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

VSTA

Oscillator start voltage

at 25°C

1.6

tSTA

Oscillator start time

VCC = 1.6 V

at 25°C

500

VCC = 3.0 V

XIN

XOUT

IC-to-IC frequency variation (1)

Reference value. TA = 25°C, VCC = 3.0 V, CMJ-145 (CL = 6 pF, 32,768 Hz) manufactured by Citizen.

–10

+10

ppm

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