DC and AC parameters M41T66
26/34 Doc ID 15108 Rev 2
Table 12. Oscillator characteristics
Figure 16. Bus timing requirements sequence
Table 11. Crystal electrical characteristics
Sym Parameter
(1)(2)
1. 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.
2. 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
f
O
Resonant frequency 32.768 kHz
R
S
Series resistance (T
A
= –40 to 70 °C) 75
(3)(4)
3. Guaranteed by design.
4. R
S (max)
= 65 kΩ for T
A
= –40 to 85 °C and oscillator startup at 1.7 V.
kΩ
C
L
Load capacitance
6
pF
7-12.5
(5)
5. External capactors must be added to achieve better clock accuracy.
Symbol Parameter Conditions Min Typ Max Unit
V
STA
Oscillator start voltage at 25 °C 1.6 V
t
STA
Oscillator start time
V
CC
= 1.6 V
at 25 °C
500 ms
V
CC
= 3.0 V 1 s
C
g
XIN 12 pF
C
d
XOUT 12 pF
IC-to-IC frequency variation
(1)
1. Reference value. T
A
= 25 °C, V
CC
= 3.0 V, CMJ-145 (C
L
= 6 pF, 32,768 Hz) manufactured by Citizen.
–10 +10 ppm
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