M48T201V-85MH1TR View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
M48T201V-85MH1TR Datasheet PDF : 37 Pages
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Clock operation
M48T201Y, M48T201V
3.8
Power-on reset
The M48T201Y/V continuously monitors VCC. When VCC falls to the power fail detect trip
point, the RST pulls low (open drain) and remains low on power-up for tREC after VCC
passes VPFD (max). The RST pin is an open drain output and an appropriate pull-up resistor
to VCC should be chosen to control rise time.
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
than tR1 and tR2 will not generate a reset condition. RSTIN1 and RSTIN2 are each internally
pulled up to VCC through a 100 KΩ resistor.
Figure 9. RSTIN1 and RSTIN2 timing waveforms
RSTIN1
RSTIN2
RST
tR1
tR2
Hi-Z
tR1HRZ
Hi-Z
tR2HRZ
AI01679
3.10
Table 8. Reset AC characteristics
Symbol
Parameter(1)
Min
Max
Unit
tR1
tR2
tR1HRZ(2)
tR2HRZ(2)
RSTIN1 low to RST low
RSTIN2 low to RST low
RSTIN1 high to RST Hi-Z
RSTIN2 high to RST Hi-Z
50
200
ns
20
100
ms
40
200
ms
40
200
ms
1. Valid for ambient operating temperature: TA = 0 to 70°C; VCC = 4.5 to 5.5 V or 3.0 to 3.6 V (except where
noted).
2. CL = 5 pF (see Figure 13 on page 28).
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.
22/37
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