ZHCS488K October 2011 – December 2018 AM3351 , AM3352 , AM3354 , AM3356 , AM3357 , AM3358 , AM3359
PRODUCTION DATA.
Figure 6-15 shows the recommended oscillator connections when OSC1 of the ZCE package is connected to an LVCMOS square-wave digital clock source and Figure 6-16 shows the recommended oscillator connections when OSC1 of the ZCZ package is connected to an LVCMOS square-wave digital clock source. The LVCMOS clock source is connected to the RTC_XTALIN terminal. The ground for the LVCMOS clock source and VSS_RTC of the ZCZ package should be connected directly to the nearest PCB digital ground (VSS). In this mode of operation, the RTC_XTALOUT terminal should not be used to source any external components. The PCB design should provide a mechanism to disconnect the RTC_XTALOUT terminal from any external components or signal traces that may couple noise into OSC1 through the RTC_XTALOUT terminal.
The RTC_XTALIN terminal has a 10- to 40-kΩ internal pullup resistor which is enabled when OSC1 is disabled. This internal resistor prevents the RTC_XTALIN terminal from floating to an invalid logic level which may increase leakage current through the oscillator input buffer.
NAME | DESCRIPTION | MIN | TYP | MAX | UNIT | |
---|---|---|---|---|---|---|
ƒ(RTC_XTALIN) | Frequency, LVCMOS reference clock | 32.768 | kHz | |||
Frequency, LVCMOS reference clock stability and tolerance(1) | Maximum RTC error = 10.512 minutes/year | –20 | 20 | ppm | ||
Maximum RTC error = 26.28 minutes/year | –50 | 50 | ppm | |||
tdc(RTC_XTALIN) | Duty cycle, LVCMOS reference clock period | 45% | 55% | |||
tjpp(RTC_XTALIN) | Jitter peak-to-peak, LVCMOS reference clock period | –1% | 1% | |||
tR(RTC_XTALIN) | Time, LVCMOS reference clock rise | 5 | ns | |||
tF(RTC_XTALIN) | Time, LVCMOS reference clock fall | 5 | ns |