Clock operation

M48T201Y, M48T201V

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3.8

Power-on reset

3.9

Reset inputs (RSTIN1 & RSTIN2)

The M48T201Y/V provides two independent inputs which can generate an output reset. The

duration and function of these resets is identical to a reset generated by a power cycle.

Figure 9 and Table 8 illustrate the AC reset characteristics of this function. Pulses shorter

Figure 9.

RSTIN1 and RSTIN2 timing waveforms

Table 8.

Reset AC characteristics

3.10

Calibrating the clock

The M48T201Y/V is driven by a quartz controlled oscillator with a nominal frequency of

32,768 Hz. The devices are factory calibrated at 25°C and tested for accuracy. Clock

accuracy will not exceed ±35 ppm (parts per million) oscillator frequency error at 25°C,

which equates to about ±1.53 minutes per month. When the calibration circuit is properly

employed, accuracy improves to better than +1/–2 ppm at 25°C.

Symbol

1.

noted).

Min

Max

Unit

RSTIN1 low to RST low

50

200

ns

RSTIN2 low to RST low

20

100

ms

(2)

2.

RSTIN1 high to RST Hi-Z

40

200

ms

(2)

RSTIN2 high to RST Hi-Z

40

200

ms

AI01679

RSTIN1

RST

RSTIN2

tR1

tR1HRZ

Hi-Z

tR2

tR2HRZ

Hi-Z