SPI-COMPATIBLE REAL-TIME CLOCK IN A SOT PACKAGE
SUNNYVALE, CA-September 6, 2001-Maxim Integrated Products introduces the MAX6902 real-time clock (RTC) with an SPI-compatible serial interface. This product is the first SPI-compatible RTC to be packaged in a tiny 8-pin SOT23. Its small size and low power consumption make it ideal for portable and battery-operated systems.
The MAX6902 real-time clock counts seconds, minutes, hours, day, month, year, and date. The end-of-the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year up to 2100. The clock operates in either 24-hour or 12-hour format with an AM/PM indicator. In addition, the MAX6902 features a pollable time/date-programmable ALARM function.
This RTC uses an external watch crystal and requires no extra crystal bias resistors or capacitors. The crystal is a standard 32.768kHz, 12.5pF load component that is readily available at low cost.
Communication with the device is carried out through an SPI-compatible interface. This interface is used to read the time or date from the timekeeping registers and set the time or date by writing to the timekeeping registers. The serial interface is also used to configure the 24-hour/12-hour mode and the AM/PM mode. The timekeeping registers can operate in burst or single read/write mode.
An enhancement of the MAX6902 is the addition of 31 bytes x 8 bits wide of SRAM for scratchpad data storage. The SRAM can be configured to operate in burst or single read/write mode.
An ideal RTC for battery-powered systems, the MAX6902 operates from a supply voltage as low as 2.0V while consuming just 400nA timekeeping supply current. The maximum supply voltage is 5.5V and operation is over the industrial temperature range (-40°C to +85°C). The SPI-compatible bus interface can operate at 1MHz over the entire supply voltage range.
Prices start from $1.45 for the MAX6902 (2500-up, FOB USA).
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