PC87417 Datasheet, PDF (242/257 Pages) National Semiconductor (TI) – LPC ServerI/O for Servers and Workstations

11.0 Device Characteristics (Continued)
Low Frequency Clock Timing
Symbol Figure
Description
Reference Conditions Min
Typ
Max Units
Clock Input Timing
t_32KCLKIN
–
Required clock period for
32KCLKIN¹
From RE to RE of
32KCLKIN.
30.5145 30.517578 30.5206 µs
(t_32TYP − (t_32TYP) (t_32TYP +
100ppm)
100ppm)
Clock Output Timing
t_32KOSC
61
Clock period of the internal _{From RE to RE of}
oscillator²
LFCKOUT.
30.517578
µs
(t_32TYP)
t_32KW
61 _{32K oscillator wake-up time}³ After V_SB > V_SBON
1
sec
t_32KD
62
Internally generated
40/48 MHz clock delay
time³
After
V_SB
>
V_SBON
33
ms
1. Recommended for RTC timekeeping accuracy and for HFCKOUT, LFCKOUT frequency accuracy.
2. Determined by the values of the external crystal circuit components.
3. Not tested. Guaranteed by characterization.
V_BAT
V_SB
32KX1/32KCLKIN
32KX2
V_BAT
V_SB
Internally Generated
40/48 MHz Clock
t_32KW
t_32KOSC
0V
0V
Figure 61. Low Frequency Clock Waveforms
0V
t_32KD
Figure 62. Internal Clock Waveforms
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