E1466D Datasheet, PDF (3/8 Pages) ATMEL Corporation – 32 KHZ CLOCK CMOS IC WITH DIGITAL TRIMMING

e1466D
Functional Descripion
Oscillator
Trimming
Capacitors
An oscillator inverter with feedback resistor is provided to generate the 32768 Hz clock fre-
quency. Values for the fixed capacitors at OSCIN and OSCOUT are mask-selectable (see
note 3 of “Operating Characteristics”). Four capacitor pads, C1 to C4, enable the users to add
integrated trimming capacitors to OSCIN, providing 15 tuning steps.
A frequency variation of typically 4 ppm for each tuning step is obtained by bonding the capac-
itor pads to OSCIN. As none of these pads are bonded, the IC is in an untrimmed state. Figure
3 shows the trimming curve characteristic.
Note: For applications which utilize this integrated trimming feature, Atmel will determine optimum val-
ues for the integrated capacitors COSCIN and COSCOUT.
Capacitor pads C1 to C4: 0 = open, 1 = connected to OSCIN
Combination C1 + C4 is redundant and therefore eliminated from the list
Table 1. Frequency Trimming Table
Capacitor Pads
C4
C3
C2
0
0
0
0
0
0
0
0
1
0
1
0
1
0
0
0
0
1
0
1
0
0
1
1
1
0
1
1
1
0
0
1
1
1
0
1
1
1
0
1
1
1
1
1
1
C1
Trimming Step
0
0
1
1
0
2
0
3
0
4
1
5
1
6
0
7
0
8
0
9
1
10
1
11
1
12
0
13
1
14
Motor Drive
Output
The e1466D 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
will be activated. Both N-channel transistors are on and conducting between output pulses.
The outputs are protected against inductive voltage spikes with diodes to both supply pins.
The motor output period and pulse width are mask-programmable, as listed below:
Available motor periods (T_M): 125, 250, 500 ms and 2, 16 s
Available max. pulse widths (t_M): 15, 6, 23.4, 31.25, 46.9 ms and 1 s
Available motor periods for motor test (T_MT): 250, 500 ms and 1 s
Note: The following constraints for combination of motor period and pulse widths have to be consid-
ered: T_M > 4 ´ t_M, T_MT > 4 ´ t_M or alternatively T_M = 2 ´ t_M, T_MT = 2 ´ t_M
3
4731A–CLOCK–06/03