Philips Semiconductors
Product specification
32 kHz watch circuits with adaptive motor
pulse
FEATURES
•
32 kHz oscillator, amplitude regulated with excellent
frequency stability
•
High immunity of the oscillator to leakage currents
•
Time calibration electrically programmable and
reprogrammable (via EEPROM)
•
A quartz crystal is the only external component required
•
Very low current consumption; typically 170 nA
•
Output for bipolar stepping motors of different types
•
Up to 50% reduction in motor current compared with
conventional circuits, by self adaption of the motor pulse
width to match the required torque of the motor
•
No loss of motor steps possible because of on-chip
detection of the induced motor voltage
•
Detector for lithium or silver-oxide battery voltage levels
•
Indication for battery end-of-life
•
Stop function for accurate timing
•
Power-on reset for fast testing
•
Various test modes for testing the mechanical parts of
the watch and the IC.
ORDERING INFORMATION
TYPE
NUMBER
PCA1461U
PCA1461U/10
PCA1462U
PCA1462U/7
PCA1462U/10
PCA1463U
PCA1463U/10
PCA1465U/10
PCA1465U/7
PCA1467U/10
Note
PACKAGE
(1)
NAME
−
−
−
−
−
−
−
−
−
−
chip in tray
chip on foil
chip in tray
chip with bumps on tape
chip on foil
chip in tray
chip on foil
chip on foil
chip with bumps on tape
chip on foil
DESCRIPTION
GENERAL DESCRIPTION
PCA146x series
The PCA146x series devices are CMOS integrated circuits
specially suited for battery-operated,
quartz-crystal-controlled wrist-watches, with a bipolar
stepping motor.
VERSION
−
−
−
−
−
−
−
−
−
−
1. Figure 1 and Chapter “Package outline” show details of standard package, available for large orders only.
Chapter “Chip dimensions and bonding pad locations” shows exact pad locations for other delivery formats.
1998 Apr 21
2
Philips Semiconductors
Product specification
32 kHz watch circuits with adaptive motor
pulse
PINNING
SYMBOL
V
SS
TEST
OSC IN
OSC OUT
V
DD
M1
M2
RESET
PIN
1
2
3
4
5
6
7
8
DESCRIPTION
ground (0 V)
test output
oscillator input
oscillator output
supply voltage
motor 1 output
motor 2 output
reset input
VSS
TEST
OSC IN
OSC OUT
1
2
PCA146x series
8
7
RESET
M2
M1
V DD
PCA146xT
3
4
MSA937
6
5
Fig.1 Pin configuration, PCA146xT, (PMFP8).
FUNCTIONAL DESCRIPTION AND TESTING
The motor output delivers pulses of six different stages
depending on the torque required to turn the motor
(Figs. 3 and 4). Every motor pulse is followed by a
detection phase which monitors the waveform of the
induced motor voltage. When a step is missed a correction
sequence will be started (Fig.2).
Motor pulses
The circuit produces motor pulses of six different stages
(stage 1 to 5, stage 8). Each stage has two independent
modes: silver-oxide and lithium. The voltage level of V
DD
determines which mode is selected (see Section “Voltage
level detector”).
Stages 1 to 5 (both modes) are used in normal operation,
stage 8 occurs under the following conditions:
•
Correction pulse after a missing step (both modes)
•
End-of-life mode
•
If stage 5 is not enough to turn the motor (both modes).
In the silver-oxide mode, the ON state of the motor pulse
varies between 56.25% and 100% of the duty factor
t
DF
= 977
µs
depending on the stage (Fig.3). It increases
in steps of 6.25% per stage.
In the lithium mode, the ON state of the motor pulse is
reduced by 18.75% of the duty factor t
DF
(Fig.4) to
compensate for the increase in the voltage level.
After a RESET the circuit always starts and continues with
stage 1, when all motor pulses have been executed.
A failure to execute all motor pulses results in the circuit
going into stage 2, this sequence will be repeated through
to stage 8.
When the motor pulses at stage 5 are not large enough to
turn the motor, stage 8 is implemented for a maximum of
8 minutes with no attempt to keep current consumption
low. After stage 8 has been executed the procedure is
repeated from RESET.
The circuit operates for 8 minutes at a fixed stage, if every
motor pulse is executed. The next 480 motor pulses are
then produced at the next lower stage unless a missing
step is detected. If a step is missed a correction sequence
is produced and for a maximum of 8 minutes the motor
pulses are increased by one stage.
1998 Apr 21
3
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