M41ST85W_06 Datasheet, PDF (1/34 Pages) STMicroelectronics – 3.0/3.3V I2C Combination Serial RTC, NVRAM Supervisor and Microprocessor Supervisor

M41ST85W
3.0/3.3V I²C Combination Serial RTC, NVRAM
Supervisor and Microprocessor Supervisor
KEY FEATURES
■ AUTOMATIC BATTERY SWITCHOVER and
WRITE PROTECT FOR:
– Internal Serial RTC and
– External low power SRAM (LPSRAM)
■ 400kHz I²C SERIAL INTERFACE
■ 3.0/3.3V OPERATING VOLTAGE
– V_CC = 2.7 to 3.6V
■ ULTRA-LOW BATTERY SUPPLY CURRENT
of 500nA (max)
■ RoHS COMPLIANCE
Lead-free components are compliant with the
RoHS Directive.
Serial RTC Features
■ 400kHz I²C
■ 44 Bytes of General Purpose NVRAM
■ Counters for:
– Seconds, Minutes, Hours, Day, Date,
Month, and Year
– Century
– 10ths/100ths of seconds
– Clock Calibration register allows
compensation for crystal variations over
temperature
■ Programmable Alarm with Repeat Modes
– Functions in Battery Back-up Mode
■ Power-down Timestamp (HT Bit)
■ 2.5 to 5.5V Oscillator Operating Voltage
Microprocessor Supervisor Features
■ Programmable Watchdog
– 62.5ms to 128s time-out period
■ Power-on Reset/Low Voltage Detect
– Open drain reset output
– Reset voltage, V_PFD = 2.60V (nom)
– Two Reset input pins
– Watchdog can be steered to Reset output
■ Early Power-fail Warning circuit (PFI/PFO)
with 1.25V Precision Reference
January 2006
Figure 1. 28-pin SOIC Package
SNAPHAT (SH)
Battery & Crystal
28
1
SOH28 (MH)
Figure 2. 28-pin (300mil) SOIC Package
EMBEDDED Crystal
SOX28 (MX)
NVRAM Supervisor Features
■ Non-volatizes external LPSRAM
– Automatically switches to back-up battery
and deselects (write-protects) external
LPSRAM via chip-enable gate
– Power-fail deselect (write protect) voltage,
V_PFD = 2.60V (nom)
– Switchover , V_SO = 2.50V (nom)
■ Battery Monitor (Battery Low flag)
Other Features
■ Programmable Squarewave Generator (1Hz
to 32KHz)
■ –40°C to +85°C Operation
■ Package Options:
– 28-lead SNAPHAT^® IC (SOH28)
SNAPHAT Batter/Crystal top to be
ordered separately.
– 28-lead Embedded Crystal SOIC
(SOX28)
Rev 8.0
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