PCF8583 datasheet(24/37 Pages) PHILIPS

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PCF8583

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Product data sheet

Rev. 06 — 6 October 2010

24 of 37

NXP Semiconductors

PCF8583

Clock and calendar with 240 x 8-bit RAM

11. Application information

11.1 Quartz frequency adjustment

11.1.1 Method 1: Fixed OSCI capacitor

By evaluating the average capacitance necessary for the application layout, a fixed

capacitor can be used. The frequency is measured using the 1 Hz signal available after

power-on at the interrupt output (pin 7). The frequency tolerance depends on the quartz

crystal tolerance, the capacitor tolerance and the device-to-device tolerance. Average

deviations of

±5 minutes per year are possible.

11.1.2 Method 2: OSCI trimmer

Using the alarm function (via the I2C-bus) a signal faster than the 1 Hz is generated at the

interrupt output for fast setting of a trimmer.

Procedure:

• Power the device on

• Initialize the device (alarm functions).

Routine:

• Set clock to time t and set alarm to time t + Δt

• at time t + Δt (interrupt) repeat routine.

11.1.3 Method 3: Direct measurement

Direct measurement of oscillator output (allowing for test probe capacitance).

PCF8583 Datasheet(PDF) 24 Page - NXP Semiconductors