Features
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32-kHz Oscillator
1.3 V to 1.8 V Operating-voltage Range
180 nA Typical Current Consumption
Voltage Regulator
Integrated Capacitors, Mask Selectable
Mask Options for Pad Designation, Motor Period and Motor Pulse Width
Low Resistance Outputs for Bipolar Stepping Motor
Motor Fast-test Function
Description
The e1217X is an integrated circuit in CMOS silicon gate technology for analog
watches. It consists of a 32-kHz oscillator, frequency dividers down to 1/64 Hz, output
pulse formers and push-pull motor drivers. Integrated capacitors are provided (select-
able mask option) for tuning of the crystal. Low current consumption and high
oscillator stability are enabled by an on-chip voltage regulator.
32-kHz
Standard Watch
CMOS IC
e1217X
4728A–CLOCK–06/03
1
e1217X
Functional Description
Voltage Regulator
An integrated voltage regulator provides the oscillator with a well-controlled negative
supply voltage V
REG
. This improves the stability of the oscillator and keeps current con-
sumption at a minimum.
The oscillator inverter with feedback resistor generates the 32768 Hz clock frequency. A
total capacitance of 24 pF is integrated. This can be selected for COSCOUT in 2 pF
increments via a mask option.
A 21-bit binary counter is provided, dividing the oscillator frequency down to 1/64 Hz.
The leading six stages are connected to V
DD
and V
REG
, while the remaining 15 stages
are connected to V
DD
and V
SS
.
The e1217X contains two push-pull output buffers for driving bipolar stepping motors.
During a motor pulse, the n-channel device of one buffer and the p-channel device of
the other buffer are activated. The p-channel devices of both buffers are active (see Fig-
ure 3) between the two pulses.
Cycle time and pulse width can be chosen via a metal mask option (Table 1).
Oscillator
Frequency Divider
Motor Drive Output
RESET
A debounced RESET input is provided. Connecting the RESET input to V
DD
resets the
12 low-order stages of the frequency divider, thus disabling further motor pulses. Motor
pulses, which are in progress when the reset function is applied, will be completed. After
releasing the RESET pad from V
DD
, the next motor pulse appears with a delay of one
half motor cycle on the drive output opposed to the former (Figure 4). Due to the
debounce circuitry on the RESET input, V
DD
must be applied for at least 31.2 ms. Dur-
ing RESET the input current is limited to 8 nA typically.
A test frequency of 512 Hz is output to this pad which can be measured with a high
resistance probe (R
³
10 M
W
, C
³
20 pF). This signal can be used for testing and tuning
the oscillator. Connecting TEST to V
DD
for at least 4 ms changes the motor cycle time
from the selected value to the test cycle time (mask options), while the motor pulse
width remains unchanged (Figure 3).
This feature can be used to reduce the amount of time required for testing the mechani-
cal parts of the watch.
Table 1.
Motor Options
Motor-cycle Parameters
Cycle time T
M
Motor pulse width t
M
Motor test cycle time T
MT
Value
2, 4, 6, 8, 10, 12, 20, 24, 30, 40, 60, 80, 120 s
0.98 to 14.65 ms in increments of 0.98 ms
250, 125, 62.5 ms
Test
3
4728A–CLOCK–06/03
Absolute Maximum Ratings
Absolute maximum ratings define parameter limits which, if exceeded, may permanently change or damage the device.
All inputs and outputs on Atmel’s circuits are protected against electrostatic discharges. However, precautions to minimize
the build-up of electrostatic charges during handling are recommended.
The circuit is protected against supply-voltage reversal for typically 5 minutes.
Parameters
Supply voltage
Input voltage range, all inputs
Output short-circuit duration
Power dissipation (DIL package)
Operating ambient temperature range
Storage temperature range
Lead temperature during soldering at 2 mm
distance, 10 s
P
tot
T
amb
T
stg
T
sld
Symbol
V
SS
V
IN
Value
-0.3 to +5
(V
SS
- 0.3 V)
£
V
IN
£
(V
DD
+ 0.3 V)
indefinite
125
-20 to +70
-40 to +125
260
mW
°C
°C
°C
Unit
V
V
Operating Characteristics
V
DD
= 0 V; V
SS
= -1.55 V; T
amb
= +25
°
C; C
TR
= 15 pF, unless otherwise specified.
All voltage levels are measured with reference to V
DD
. Test crystal as specified below.
Parameters
Operating voltage
Operating current
RESET input current
Motor Outputs
Motor output current
Motor period
Motor pulse width
Motor test period
Oscillator
Stability
Start-up voltage
Integrated input capacitor
Integrated output capacitor
Note:
C
OSCOUTmax
= 24 pF
1. Typical parameters represent the statistical mean values.
DV
SS
= 100 mV, C
TR
= 5 pF
Startup within 2 s
Df/f
V
ST
C
OSC IN
C
OSC OUT
-1.3
See Table 2
See Table 2
0.1
ppm
V
pF
pF
R
L
= 2 kW, V
SS
= -1.55 V
I
M
T
M
T
M
T
MT
±0.7
See Table 2
See Table 2
See Table 2
mA
s
ms
ms
Test Conditions
Functional test (Figure 2)
C
oscout
= 16 pF, R
L
= R
RESET = V
DD
Symbol
V
SS
I
SS
I
R
Min.
-1.3
-180
8
Typ.
(1)
Max.
-1.8
-300
Unit
V
nA
nA
4
e1217X
4728A–CLOCK–06/03
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