PCA2000UAC datasheet(15/30 Pages) NXP

15 / 30 page

PCA2000_2001

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Product data sheet

Rev. 08 — 23 August 2010

15 of 30

NXP Semiconductors

PCA2000; PCA2001

32 kHz watch circuit with programmable adaptive motor pulse

Measuring states:

• State 1: quartz crystal oscillator frequency divided by 1024; state 1 starts with a pulse

to VP and ends with a second pulse to VP

• State 2: inhibition time has a value of n × 0.122 ms. A signal with periodicity of

31.25 ms + n

× 0.122 ms appears at pad RESET and as current modulation at

pad VDD (see Figure 11 and Figure 12)

7.11 Customer testing

Connecting pad RESET to VSS activates the test mode. In this test mode, the motor

output frequency is 8 Hz; the duty cycle reduction and battery check occurs every second,

instead of every 4 minutes. If the supply voltage drops below the EOL threshold voltage,

the motor output frequency is 32 Hz with the highest driving level.

7.12 EOL of battery

The supply voltage is checked every 4 minutes. If it drops below the EOL threshold

voltage (1.38 V for silver-oxide, 2.5 V for lithium batteries), the motor steps change from

one pulse per second to a burst of four pulses every 4 seconds. The step detection is

switched off, and the motor is driven with the highest pulse level.

Only the PCA2000 has an EOL function.

Fig 11. Output waveform at pad RESET for instruction state 2

Fig 12. Supply voltage modulation for starting and stopping of instruction state 2

mgw355

VDD

VSS

31.25 ms

+ inhibition time

VO(dif)

VDD

VP(prog)(start)

VP(mod)

VP(prog)(stop)

tp(start)

VSS

VDD(nom)

mgu719

tp(stop)

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