مدار مجتمع (آی سی) آی‌سی کلاک و زمان‌بندی ساعت زمان واقعی (آر‌تی‌سی)

Product Attributes

Introduction

SD8908 is a real-time clock IC with a 3-wire interface, through which the CPU can read and write on-chip register data, including time registers, control registers, battery level registers, 31-byte user SRAM registers, and 8-byte ID registers. The chip features a backup battery input pin VBAT, with an internal charging circuit that intelligently charges an external rechargeable battery or supercapacitor. The charging voltage can be set to 3.3V or 4.2V via bit selection, and battery or supercapacitor voltage measurement is supported. SD8908 integrates a communication verification function to validate interface communication data, with verification results automatically saved to dedicated registers, significantly enhancing RTC data reliability. The chip has a built-in crystal oscillator with an accuracy of 5ppm at room temperature. In addition, each chip contains a unique 8-byte ID code. The pinout is compatible with DS1302.

Features

• Low power consumption: typical 0.6μA (Ta = 25℃).
• Operating voltage range: 2.5V ~ 5.5V; operating temperature range: -40℃ ~ 105℃.
• SPI interface communication, maximum speed 2MHz.
• Year, month, day, day-of-week, hour, minute, and second in BCD input/output; each time register individually addressable.
• Automatic leap year adjustment (2000 ~ 2099).
• Built-in charging function; 3.3V or 4.2V charging voltage selectable via bit setting.
• Built-in crystal oscillator; accuracy better than ±5ppm at room temperature.
• Built-in battery voltage and temperature measurement; current battery voltage and temperature readable via interface.
• Built-in digital timekeeping accuracy adjustment for improved timing precision.
• Built-in communication checksum for enhanced communication reliability.
• 32.768kHz square wave output via I/O pin for fast SD8908 timekeeping accuracy measurement.
• Built-in write protection to prevent accidental writes to clock data and ensure data integrity.
• Built-in 31-byte general-purpose SRAM registers for user data storage.
• Built-in 8-byte identification code; globally unique ID preset before shipment.
• Passes 4kV burst test on evaluation board.
• Pin ESD withstand voltage greater than 4kV.
• CMOS process.
• Package: SOP8.