M41ST87WMX6TR STMicroelectronics, M41ST87WMX6TR Datasheet - Page 26

• Manufacturer Part Number: M41ST87WMX6TR
• Description: IC SUPERVISOR RTC 160X8 28-SOIC
• Manufacturer: STMicroelectronics
• Type: Clock/Calendar/Supervisorr

Specifications of M41ST87WMX6TR

• Memory Size: 160B
• Time Format: HH:MM:SS:hh (24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC, 28-SOH (8.48mm Width)
• Bus Type: Serial (2-Wire, I2C)
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.6V
• Operating Supply Voltage (min): 2.7V
• Operating Temperature Classification: Industrial
• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Pin Count: 28
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6457-2; M41ST87WMX6TR

Operating modes
2.10
26/48
Avoiding inadvertent tampers (normally closed
configuration)
In some applications it may be necessary to use a low pass filter to reduce electrical noise
on the tamper input pin when the TCM
the tamper detect switch is located some distance (> 6”) from the tamper input pin. A low
pass filter can prevent unwanted, higher frequency noise from inadvertently being detected
as a tamper condition caused by the “antenna-effect” (produced by a longer signal wire or
mesh). This low pass filter can be constructed using a series resistor (R) in conjunction with
a capacitor (C) on the tamper input pin.
The cut-off frequency f
Figure 20. Low-pass filter implementation for noise immunity
Table 6.
10000
10000
R ( )
1000
1000
5000
5000
Calculated cut-off frequency for typical capacitance and resistance
values
c
is determined according to the formula:
To Tamper Detect Switch
1.00E-09
1.00E-06
1.00E-09
1.00E-06
1.00E-09
1.00E-06
C (F)
f c
X
=
bit = 0 (normally closed). This is especially true if
1
2 Pi R C
R
15.9 MHz
159.2 Hz
31.8 kHz
15.9 kHz
31.8 Hz
15.9 Hz
f
c
C
AI11185
TP IN
M41ST87Y, M41ST87W
6.28 ms
31.4 ms
62.8 ms
6.28 µs
31.4 µs
62.8 µs
1/f
c
(s)