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See Technical Specifications

M41ST87WMX6TR

5.0 V, 3.3/3.0 V secure real-time clock , NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM

Manufacturer:

STMicroelectronics, Inc
Mfr.Part #:

M41ST87WMX6TR
Datasheet:

M41ST87WMX6TR Datasheet (PDF)
Programmable:

Not Verified
Type:

Clock/Calendar
Features:

Alarm, Leap Year, NVSRAM, Square Wave Output, Supervisor, Watchdog Timer
Memory Size:

128B
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M41ST87WMX6TR General Description

The M41ST87Y/W secure serial RTC and NVRAM supervisor is a low power 1280-bit, static CMOS SRAM organized as 160 bytes by 8 bits. A built-in 32.768 kHz oscillator (internal crystal-controlled) and 8 bytes of the SRAM are used for the clock/calendar function and are configured in binary coded decimal (BCD) format.An additional 11 bytes of RAM provide calibration, status/control of alarm, watchdog, tamper, and square wave functions. 8 bytes of ROM and finally 128 bytes of user RAM are also provided. Addresses and data are transferred serially via a two line, bidirectional I2C interface. The built-in address register is incremented automatically after each WRITE or READ data byte. The M41ST87Y/W has a built-in power sense circuit which detects power failures and automatically switches to the battery supply when a power failure occurs. The energy needed to sustain the SRAM and clock operations can be supplied by a small lithium button-cell supply when a power failure occurs.Functions available to the user include a non-volatile, time-of-day clock/calendar, alarm interrupts, tamper detection, watchdog timer, and programmable square wave output. Other features include a power-on reset as well as two additional debounced inputs (RSTIN1andRSTIN2) which can also generate an output reset (RST). The eight clock address locations contain the century, year, month, date, day, hour, minute, second and tenths/hundredths of a second in 24-hour BCD format. Corrections for 28, 29 (leap year), 30 and 31 day months are made automatically.

Key Features

5.0, 3.3, or 3.0 V operation
400 kHz I²C bus
NVRAM supervisor to non-volatize external LPSRAM
2.5 to 5.5 V oscillator operating voltage
Automatic switchover and deselect circuitry
Choice of power-fail deselect voltages
- M41ST87Y: (not recommended for new design, contact ST sales office for availability) THS = 1: V_PFD≈ 4.63 V; V_CC= 4.75 to 5.5 V THS = 0: V_PFD≈ 4.37 V; V_CC= 4.5 to 5.5 V
- M41ST87W: THS = 1: V_PFD≈ 2.9 V; V_CC= 3.0 to 3.6 V THS = 0: V_PFD≈ 2.63 V; V_CC= 2.7 to 3.6 V
Two independent power-fail comparators (1.25 V reference)
Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century
128 bytes of clearable, general purpose NVRAM
Programmable alarm and interrupt function (valid even during battery backup mode)
Programmable watchdog timer
Unique electronic serial number (8-byte)
32 kHz frequency output available upon power-on
Microprocessor power-on reset output
Battery low flag
Ultra-low battery supply current of 500 nA (typ)
Security features
- Tamper indication circuits with timestamp and RAM clear
- LPSRAM clear function (TP_CLR)
- Packaging includes a 28-lead, embedded crystal SOIC and a 20-lead SSOP
- Oscillator stop detection

Specifications

Category	Integrated Circuits (ICs)Clock/TimingReal Time Clocks	Series	-
Programmable	Not Verified	Type	Clock/Calendar
Features	Alarm, Leap Year, NVSRAM, Square Wave Output, Supervisor, Watchdog Timer	Memory Size	128B
Time Format	HH:MM:SS:hh (24 hr)	Date Format	YY-MM-DD-dd
Interface	I²C, 2-Wire Serial	Voltage - Supply	2.7V ~ 3.6V
Voltage - Supply, Battery	2.5V ~ 3.6V	Current - Timekeeping (Max)	0.5mA @ 2.7V ~ 3.6V
Operating Temperature	-40°C ~ 85°C	Mounting Type	Surface Mount
Base Product Number	M41ST87