R2033K datasheet(9/50 Pages) RICOH

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R2033K/T

GENERAL DESCRIPTION

• Interface with CPU

The R2033K/T is connected to the CPU by three signal lines CE (Chip Enable), SCLK (Serial Clock), and SIO

(Serial Input and Output), through which it reads and writes data from and to the CPU.

The CPU can be

accessed when the CE pin is held high.

Access clock pulses have a maximum frequency of 1 MHz allowing

high-speed data transfer to the CPU.

• Clock and Calendar Function

The R2033K/T reads and writes time data from and to the CPU in units ranging from seconds to the last two

digits of the calendar year. The calendar year will automatically be identified as a leap year when its last two

digits are a multiple of 4.

Consequently, leap years up to the year 2099 can automatically be identified as such.

*) The year 2000 is a leap year while the year 2100 is not a leap year.

• Alarm Function

The R2033K/T incorporates the alarm interrupt circuit configured to generate interrupt signals to the CPU at

preset times. The alarm interrupt circuit allows two types of alarm settings specified by the Alarm_W registers

and the Alarm_D registers. The Alarm_W registers allow week, hour, and minute alarm settings including

combinations of multiple day-of-week settings such as "Monday, Wednesday, and Friday" and "Saturday and

Sunday". The Alarm_D registers allow hour and minute alarm settings. The Alarm_W outputs from INTR pin,

and the Alarm_D outputs also from /INTR pin. Each alarm function can be checked from the CPU by using a

polling function.

• High-precision Oscillation Adjustment Function

The R2033K/T has built-in oscillation stabilization capacitors (CG and CD), which can be connected to an

external crystal oscillator to configure an oscillation circuit. Two kinds of accuracy for this function are

alternatives. To correct deviations in the oscillator frequency of the crystal, the oscillation adjustment circuit is

configured to allow correction of a time count gain or loss (up to

±1.5ppm or ±0.5ppm at 25°C) from the CPU.

The maximum range is approximately

±189ppm (or ±63ppm) in increments of approximately 3ppm (or 1ppm).

Such oscillation frequency adjustment in each system has the following advantages:

Allows timekeeping with much higher precision than conventional RTCs while using a crystal oscillator with a

wide range of precision variations.

Corrects seasonal frequency deviations through seasonal oscillation adjustment.

Allows timekeeping with higher precision particularly with a temperature sensing function out of RTC, through

oscillation adjustment in tune with temperature fluctuations.

• Power-on Reset, Oscillation Halt Sensing Function and Supply Voltage Monitoring Function

The R2033K/T incorporates an oscillation halt sensing circuit equipped with internal registers configured to

record any past oscillation halt.

Power on reset function reset the control resisters when the system is powered on from 0V. At the same time,

the fact is memorized to the resister as a flag, thereby identifying whether they are powered on from 0V or

battery backed-up.

The R2033K/T also incorporates a supply voltage monitoring circuit equipped with internal registers configured

to record any drop in supply voltage below a certain threshold value. Supply voltage monitoring threshold

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