MCP2140A Microchip Technology, MCP2140A Datasheet - Page 8

• Manufacturer Part Number: MCP2140A
• Description: IrDA Standard Protocol Stack Controller With Fixed 9600 Baud Communication Rate
• Manufacturer: Microchip Technology

MCP2140A
2.3.1.1
A crystal or ceramic resonator can be connected to the
OSC1 and OSC2 pins to establish oscillation (refer to
Figure
the use of a parallel-cut crystal. Use of a series cut
crystals may give a frequency outside of the crystal
manufacturers specifications.
FIGURE 2-1:
TABLE 2-1:
TABLE 2-2:
DS22050A-page 8
See
values of C1 and C2.
Note:
Note:
3.6864 MHz
Note:
3.6864 MHz
Resonator
Freq
Ceramic
2-1). The MCP2140A oscillator design requires
XTAL
Table 2-1
Freq
C1
C2
Higher capacitance increases the stability
of the oscillator, but also increases the
start-up time. These values are for design
guidance only. Since each resonator has
its own characteristics, the user should
consult the resonator manufacturer for
appropriate
components.
Higher capacitance increases the stability
of the oscillator but also increases the
start-up time. These values are for design
guidance only. R
avoid overdriving crystals with low drive
level specification. Since each crystal has
its own characteristics, the user should
consult the crystal manufacturer for
appropriate
components.
Crystal Oscillator / Ceramic
Resonators
A series resistor may be required for
AT strip cut crystals.
(Note)
and
RS
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
OSC2
OSC1
OSC1 (C1)
15 - 30 pF
CRYSTAL OPERATION
(CERAMIC RESONATOR)
Table 2-2
OSC1 (C1)
10 - 22 pF
values
values
RF
S
may be required to
for recommended
MCP2140A
of
of
OSC2 (C2)
15 - 30 pF
OSC2 (C2)
10 - 22 pF
To internal
logic
external
external
2.3.1.2
For applications where a clock is already available
elsewhere, users may directly drive the MCP2140A
provided that this external clock source meets the AC/
DC timing requirements listed in
Diagrams and
how an external clock circuit should be configured.
FIGURE 2-2:
2.3.2
The device crystal is used to derive the communication
bit clock (BITCLK). There are 16 BITCLKs for each bit
time. The BITCLKs are used for the generation of the
start bit and the eight data bits. The stop bit uses the
BITCLK when the data is transmitted (not for
reception).
This clock is a fixed-frequency and has minimal
variation in frequency (specified by the crystal
manufacturer).
Clock From
external
system
Open
BIT CLOCK
External Clock
Specifications”.
EXTERNAL CLOCK
© 2007 Microchip Technology Inc.
OSC1
OSC2
Section 4.3 “Timing
MCP2140A
Figure 2-2
shows