M41ST87WMX6 STMicroelectronics, M41ST87WMX6 Datasheet - Page 26

• 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

Operating modes
2.7
Note:
2.8
Note:
Note:
26/54
Tamper detection operation
The tamper pins are triggered based on the state of an external switch. Two switch mode
options are available, normally open or normally closed, based on the setting of the tamper
connect mode bit (TCM
tamper pin will be triggered by being connected to V
(if the TPM
switch is closed, the tamper bit (TB
if the device has been physically tampered with. If the selected switch mode is normally
closed (TCM
(depending on the state of the TPM
result of opening the external switch.
When a tamper event occurs, the tamper bits (TB1 and/or TB2) will be immediately set if
TEB
If the tamper interrupt enable bit (TIE
The IRQ/OUT output is cleared by a READ of the flags register (as seen in
page
In order to avoid an inadvertent activation of the IRQ/OUT pin due to a prior tamper event,
the flag register (0Fh) should be read prior to resetting the TEB
The tamper bits are “read only” bits and are reset only by writing the tamper enable bit
(TEB
register to clear the IRQ pin, then clear the TEB
TEB
The tamper detect function operates both under normal power, and in battery backup. Even
if the trigger event occurs during a power-down condition, the tamper flag bit(s) will be set
correctly.
Sampling
As the switch mode normally closed (TCM
maintain constant monitoring, the M41ST87Y/W offers a programmable tamper detect
sampling bit (TDS
page
approximately 1 ms.
When TEB
tamper event has been detected, no additional current will be drawn.
The oscillator must be running for tamper detection to operate in the sampling mode. If the
oscillator is stopped, the tamper detection circuit will revert to constant monitoring.
Sampling in the tamper high mode (TPM
connecting the TPx
monitoring when V
on page
X
x
X
34), a reset of the TIE bit to '0,' or the RST output is asserted.
23). When enabled, the sampling frequency is once per second (1Hz), for a duration of
to again enable the tamper circuit.
= '1.'
) to '0.' Thus, when servicing a tamper interrupt, the user should read the flags
20).
X
X
is disabled, no current will be drawn by the tamper detection circuit. After a
X
bit is set to '1'), through the closing of the external switch. When the external
= '0'), the tamper pin will be triggered by being pulled to V
X
CC
) to reduce the current drawn on V
IN
pin to V
is “on” and revert to sampling when in battery backup (see
X
). If the selected switch mode is normally open (TCM
CC
Doc ID 9497 Rev 9
through an external resistor. This will allow constant
x
X
) will be immediately set, allowing the user to determine
X
bit), through an internal pull-up/pull-down resistor as a
) is set to a '1,' the IRQ/OUT pin will also be activated.
X
X
= '1') may be bypassed while on V
= '0') requires a greater amount of current to
x
bit to clear the TB
SS
CC
(if the TPM
or V
BAT
X
(see
bit.
X
x
M41ST87Y, M41ST87W
bit is set to '0') or to V
flag, followed by setting
Figure 17 on
SS
Figure 24 on
or to V
CC
X
= '1'), the
by
Figure 14
OUT
CC