Datasheet
Table 14. Crystal electrical characteristics
Sym
Parameter
(1)
(2)
Min. Typ. Max. Units
f
O
Resonant frequency - 32.768 kHz
R
S
Series resistance (T
A
= –40 to 70 °C, oscillator startup at 2.0 V)
-
75
(3)
(4)
kΩ
C
L
Load capacitance - 6 pF
1. Load capacitors are integrated within the M41T6x. 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.
2. For the QFN16 package, user-supplied external crystals are required. The 6 and 7 pF crystals listed in
Table 15. Crystals suitable for use with M41T6x series RTCs have been evaluated by ST and have been
found to be satisfactory for use with the M41T6x series RTC.
3. R
S (max)
= 65 kΩ for T
A
= –40 to 85 °C and oscillator startup at 1.5 V.
4. Guaranteed by design.
Table 15. Crystals suitable for use with M41T6x series RTCs
Vendor Order number Package
Manufacturer’s specifications
ESR
max.
Temp. range
(°C)
Rated
tolerance at
25 °C
Rated load
cap.
Citizen CMJ206T-32.768KDZB-UB 8.3 x 2.5 mm leaded SMT 50 kΩ –40/+85 ±20 ppm 6 pF
Citizen CM315-32.768KDZY-UB 3.2 x 1.5 x 0.9 mm SMT 70 kΩ –40/+85 ±20 ppm 7 pF
Ecliptek
E4WCDA06-32.768K
(1)
2.0 x 6.0 mm thru-hole 50 kΩ –10/+60 ±20 ppm 6 pF
Ecliptek E5WSDC 07 - 32.768K 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF
ECS ECS-.327-6-17X-TR 3.8 x 8.5 x 2.5 mm SMT 50 kΩ –40/+85 ±20 ppm 6 pF
ECS ECS-.327-7-34B-TR 3.2 x 1.5 x 0.9 mm SMT 70 kΩ –40/+85 ±20 ppm 7 pF
ECS ECS-.327-7-38-TR 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF
Epson
MC-146 32.7680KA-AG: ROHS
(2)
7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF
Fox 298LF-0.032768-19 1.5 x 5.0 mm thru-hole 50 kΩ –20/+60 ±20 ppm 6 pF
Fox 299LF-0.032768-37 2.0 x 6.0 mm thru-hole 50 kΩ –20/+60 ±20 ppm 6 pF
Fox 414LF-0.032768-12 3.8 x 8.5 x 2.5 mm SMT 50 kΩ –40/+85 ±20 ppm 6 pF
Fox 501LF-0.032768-5 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF
Micro
Crystal
MS3V-T1R 32.768KHZ 7PF 20PPM
6.7 x 1.4 mm
leaded SMT
65 kΩ –40/+85 ±20 ppm 7 pF
Pletronics SM20S - 32.768K - 6pF 3.8 x 8.5 x 2.5 mm SMT 50 kΩ –40/+85 ±20 ppm 6 pF
Seiko SSPT7F-7PF20PPM 7 x 1.5 x 1.4 mm SMT 65 kΩ –40/+85 ±20 ppm 7 pF
Seiko VT200F-6PF20PPM 2.0 x 6.0 mm thru-hole 50 kΩ –10/+60 ±20 ppm 6 pF
1. ST has been informed that this crystal has been terminated by the vendor.
2. Epson MC-146 32.7680KA-E: ROHS is 6 pF version.
Table 16. Oscillator characteristics
Sym Parameter Conditions Min. Typ. Max. Unit
V
STA
Oscillator start voltage ≤ 10 seconds 1.5 V
t
STA
Oscillator start time
V
CC
= 3.0 V
1 s
C
g
XIN capacitance 12 pF
M41T62, M41T64, M41T65
DC and AC parameters
DS3840 - Rev 24
page 25/42