M40SZ100WMQ6F View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'M40SZ100WMQ6F' PDF : 25 Pages View PDF
Operation
M40SZ100Y, M40SZ100W
2.2
Power-on reset output
All microprocessors have a reset input which forces them to a known state when starting.
The M40SZ100Y/W has a reset output (RST) pin which is guaranteed to be low by VPFD
(see Table 7 on page 17). This signal is an open drain configuration. An appropriate pull-up
resistor to VCC should be chosen to control the rise time. This signal will be valid for all
voltage conditions, even when VCC equals VSS (with valid battery voltage).
Once VCC exceeds the power failure detect voltage VPFD, an internal timer keeps RST low
for tREC to allow the power supply to stabilize.
2.3
Reset input (RSTIN)
The M40SZ100Y/W provides one independent input which can generate an output reset.
The duration and function of this reset is identical to a reset generated by a power cycle.
Table 3 and Figure 8 illustrate the AC reset characteristics of this function. Pulses shorter
than tRLRH will not generate a reset condition. RSTIN is internally pulled up to VCC through a
100kΩ resistor.
Figure 8. RSTIN timing waveform
RSTIN
RST (1)
tRLRH
tR1HRH
AI04768
1. With pull-up resistor
Table 3. Reset AC characteristics
Symbol
Parameter(1)
Min
Max
Unit
tRLRH(2)
tR1HRH(3)
RSTIN low to RSTIN high
RSTIN high to RST high
200
ns
40
200
ms
1. Valid for ambient operating temperature: TA = –40 to 85°C; VCC = 2.7 to 3.6V or 4.5 to 5.5V (except where noted).
2. Pulse width less than 50ns will result in no RESET (for noise immunity).
3. CL = 5pF (see Figure 10 on page 16).
2.4
Battery low pin
The M40SZ100Y/W automatically performs battery voltage monitoring upon power-up, and
at factory-programmed time intervals of at least 24 hours. The Battery Low (BL) pin will be
asserted if the battery voltage is found to be less than approximately 2.5V. The BL pin will
remain asserted until completion of battery replacement and subsequent battery low
monitoring tests, either during the next power-up sequence or the next scheduled 24-hour
interval.
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