PCF2003 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet Rev. 1 — 20 October 2015 8 of 30
NXP Semiconductors
PCF2003
32 kHz watch circuit with programmable adaptive motor pulse
The oscillator frequency can be measured at pad RESET, where a square wave signal
with the frequency of is provided. This frequency shows a jitter every minute or
every two minutes, which originates from the time calibration, depending on the
programmed calibration period.
Details on how to measure the oscillator frequency and the programmed inhibition time
are given in Section 7.10
.
7.4 Reset
At pad RESET an output signal with a frequency of is provided.
Connecting pad RESET to V
DD
stops the motor drive and opens all four (P1, N1, P2 and
N2) driver switches (see Figure 5
). Connecting pad RESET to V
SS
activates the test
mode. In this mode the motor output frequency is 32 Hz, which can be used to test the
mechanical function of the watch.
After releasing the pad RESET, the motor starts exactly one second later with the smallest
duty cycle and with the opposite polarity to the last pulse before stopping. The debounce
time for the RESET function is between 31 ms and 62 ms.
7.5 Programming possibilities
The programming data is stored in OTP cells (EPROM cells). At delivery, all memory cells
are in state 0. The cells can be programmed to the state 1, but then there is no more set
back to state 0. The programming data is organized in an array of four 8-bit words
(see Table 5
): word A contains the time calibration, words B and C contain the setting for
the motor pulses and word D contains the type recognition.
1
1024
------------
f
osc
1
1024
------------
f
osc
32 Hz=
Table 5. Words and bits
Word Bit
1 2 3 4 5 6 7 8
A number of 8192 Hz pulses to be removed calibration
period
B lowest stage: duty cycle number of driving stages highest
stage: duty
cycle
pulse
stretching
output period
C pulse width maximum time delay between positive
and negative detection pulses
output
period
factory test
bit
D type factory test bits
Table 6. Description of word A bits
Bit Value Description
Inhibition time
1 to 7 - adjust the number of the 8192 Hz pulses to be removed;
bit 1 is the MSB and bit 7 is the LSB
Calibration period
801minute
12minutes
