COP8AME9 Datasheet, PDF (21/83 Pages) National Semiconductor (TI) – 8-Bit CMOS Flash Microcontroller with 8k Memory, Dual Op Amps, Virtual EEROM, Temperature Sensor,10-Bit A/D and Brownout Reset

10.0 Functional Description (Continued)
FIGURE 9. Brownout Reset Operation
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count. The value of the resistor is in the range of 0.5M to 2M
(typically 1.0M). Table 2 shows the component values re-
quired for various standard crystal values. Resistor R2 is
on-chip, for the high speed oscillator, and is shown for
reference. Figure 11 shows the crystal oscillator connection
diagram. A ceramic resonator of the required frequency may
be used in place of a crystal if the accuracy requirements are
not quite as strict.
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FIGURE 10. Reset Circuit Using Power-On Reset
10.8 OSCILLATOR CIRCUITS
The device has two crystal oscillators to facilitate low power
operation while maintaining throughput when required. Fur-
ther information on the use of the two oscillators is found in
Section 7.0 Power Saving Features. The low speed oscillator
utilizes the L0 and L1 port pins. References in the following
text to CKI will also apply to L0 and references to G7/CKO
will also apply to L1.
10.8.1 Oscillator
CKI is the clock input while G7/CKO is the clock generator
output to the crystal. An on-chip bias resistor connected
between CKI and CKO is provided to reduce system part
TABLE 2. Crystal Oscillator Configuration,
T_A = 25˚C, V_CC = 5V
CKI Freq.
R1 (kΩ) R2 (MΩ) C1 (pF) C2 (pF)
(MHz)
0
On Chip
18
18
10
0
On Chip
18
18
5
0
On Chip 18–36 18–36
1
5.6
On Chip
100 100–156 0.455
0
20
**
**
32.768
kHz*
*Applies to connection to low speed oscillator on port pins L0 and L1 only.
**See Note below.
21
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