M41ST87W

M41ST87Y M41ST87W 5.0 V and 3.3/3.0 V secure serial RTC and NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM 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: THS = 1: VPFD≈ 4.63 V; VCC = 4.75 to 5.5 V THS = 0: VPFD≈ 4.37 V; VCC = 4.5 to 5.5 V – M41ST87W: THS = 1: VPFD ≈ 2.9 V; VCC = 3.0 to 3.6 V THS = 0: VPFD ≈ 2.63 V; VCC = 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 poweron Microprocessor power-on reset output Battery low flag Ultra-low battery supply current of 500 nA (typ) Embedded crystal 28-pin, (300 mil) SOX28 (MX) ■ ■ SSOP20 (SS) Security features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Tamper indication circuits with timestamp and RAM clear LPSRAM clear function (TPCLR) Packaging includes a 28-lead, embedded crystal SOIC and a 20-lead SSOP Oscillator stop detection April 2010 Doc ID 9497 Rev 8 1/52 www.st.com 1 www.DataSheet.in Contents M41ST87Y, M41ST87W Contents 1 Description . . . . ...