SX18AC/SO Parallax Inc, SX18AC/SO Datasheet - Page 20

• Manufacturer Part Number: SX18AC/SO
• Description: IC MCU 2K FLASH 50MHZ SO-18
• Manufacturer: Parallax Inc
• Series: SXr

Specifications of SX18AC/SO

• Core Processor: RISC
• Core Size: 8-Bit
• Speed: 50MHz
• Number Of I /o: 12
• Program Memory Size: 3KB (2K x 12)
• Program Memory Type: FLASH
• Ram Size: 137 x 8
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 18-SOIC
• Voltage - Supply (vcc/vdd): -
• Eeprom Size: -
• Data Converters: -
• Peripherals: -
• Connectivity: -

SX18AC / SX20AC / SX28AC
9.0 OSCILLATOR CIRCUITS
The device supports several user-selectable oscillator
modes. The oscillator modes are selected by program-
ming the appropriate values into the FUSE Word register.
These are the different oscillator modes offered:
9.1 XT, LP or HS modes
In XT, LP or HS, modes, you can use either an external
resonator network or an external clock signal as the
device clock.
To use an external resonator network, you connect a
crystal or ceramic resonator to the OSC1/CLKIN and
OSC2/CLKOUT pins according to the circuit configura-
tion shown in Figure 9-1. Table 9-1 shows the recom-
mended capacitor values to be used with ceramic
resonators. Table 9-2 shows the recommended compo-
nent values to be used at different crystal frequencies. A
parallel resonant crystal type is recommended. Use of a
series resonant crystal may result in a frequency that is
outside the crystal manufacturer specifications.
If the XT, LP, or HS mode is selected, the OSC1/CLKIN
pin can driven by an external clock source rather than a
resonator network, as long as the clock signal meets the
specified duty cycle, rise and fall times, and input levels
(Figure 9-2). In this case, the OSC2/CLKOUT pin should
be left open.
Figure 9-1. Crystal Operation (or Ceramic Resonator)
Note:Series resistor (R
higher than 1 MHz; use a direct connection instead.
© 1998 Scenix Semiconductor, Inc. All rights reserved.
LP: Low Power Crystal
XT: Crystal/Resonator
HS: High Speed Crystal/Resonator
RC: External Resistor/Capacitor
Internal Resistor/Capacitor
(HS, XT or LP OSC Configuration)
OSC1
C
1
S
SX Device
SLEEP
) is not required for frequencies
XTAL
RF
Internal
Circuitry
OSC2
RS
C
2
- 20 -
* Note: Resonator with built-in capacitors.
Clock
Mode
XT
XT
XT
HS
HS
HS
HS
HS
HS
HS
HS
HS
HS
HS
Figure 9-2. External Clock Input Operation
Resonator
Frequency
50 MHz*
Table 9-1. Capacitor Selection for
455 kHz
(HS, XT or LP OSC Configuration)
12 MHz
12 MHz
16 MHz
16 MHz
20 MHz
33 MHz
1 MHz
2 MHz
4 MHz
4 MHz
8 MHz
8 MHz
Generated Clock
Ceramic Resonators
OSC1
Externally
Internal
Internal
Internal
Internal
Internal
220 pF 220 pF
100 pF 100 pF
100 pF 100 pF 100 k
100 pF 100 pF 100 k
(47 pF)
(47 pF)
(22 pF)
(15 pF)
(5 pF)
30 pF
30 pF
15 pF
10 pF
10 pF
C1
SX Device
Internal
Internal
Internal
Internal
Internal
(47 pF)
(47 pF)
(22 pF)
(15 pF)
Open
(5 pF)
30 pF
30 pF
15 pF
10 pF
10 pF
C2
OSC2
100 k
33 k
33 k
1 M
1 M
1 M
1 M
1 M
1 M
1 M
1 M
1 M
www.scenix.com
R
F
6.8 k
6.8 k
680
470
470
R
0
0
0
0
0
0
0
0
0
S