M41ST87WMX6 STMicroelectronics, M41ST87WMX6 Datasheet - Page 27

• Manufacturer Part Number: M41ST87WMX6
• Description: IC SUPERVISOR RTC 160X8 28-SOIC
• Manufacturer: STMicroelectronics
• Type: Clock/Calendar/Supervisorr

Specifications of M41ST87WMX6

• 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)
• Function: Clock/Calendar/Alarm/Timer Interrupt
• Rtc Memory Size: 160 Byte
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: Serial (2-Wire, I2C)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-5370-5; M41ST87WMX6

M41ST87Y, M41ST87W
2.9
2.10
Internal tamper pull-up/down current
Depending on the capacitive and resistive loading of the tamper pin input (TP
may require more or less current from the internal pull-up/down used when monitoring the
normally closed switch mode. The state of the tamper current hi/tamper current low bit
(TCHI/TCLO
1 MΩ pull-up/-down resistor, while TCHI/TCLO
(see
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 21. Low-pass filter implementation for noise immunity
Table 6.
Figure 18 on page
10000
10000
R (Ω)
1000
1000
5000
5000
X
Calculated cut-off frequency for typical capacitance and resistance
values
) determines the sizing of the internal pull-up/-down. TCHI/TCLO
c
24).
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
Doc ID 9497 Rev 9
C (F)
f c
X
=
bit = 0 (normally closed). This is especially true if
1
⁄
(
2 Pi R C
⋅
X
= '0' uses a 10 MΩ pull-up/-down resistor
⋅
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
Operating modes
6.28 ms
31.4 ms
62.8 ms
6.28 µs
31.4 µs
62.8 µs
1/f
XIN
X
c
= '1' uses a
), the user
(s)
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