MCP2140 Microchip Technology, Inc., MCP2140 Datasheet - Page 17

• Manufacturer Part Number: MCP2140
• Description: The MCP2140 Embeds Irda Protocol Handling And Bit Encoding/decoding, And Provides The Lowest Cost, Lowest Power Consumption Solution For Adding Irda Connectivity to Embedded Systems
• Manufacturer: Microchip Technology, Inc.

2.13
The MCP2140 requires an infrared transceiver for the
optical interface. This transceiver can be a single-chip
solution (integrated) or be implemented with discrete
devices.
2.13.1
The MCP2140 was designed to use a discrete imple-
mentation that allows the lowest system power
consumption as well as a low cost implementation.
Figure 2-12
transceiver circuit.
FIGURE 2-11:
Care must be taken in the design and layout of the
photo-detect circuit, due to the small signals that are
being detected and their sensitivity to noise.
This figure will be available in Revision B of the
MCP2140 data sheet. Please conact the Microchip
factory via email ([e-mail])
for additional information.
2003 Microchip Technology Inc.
Optical Interface
DISCRETE TRANSCEIVER
SOLUTION
shows
CIRCUIT FOR A
DISCRETE OPTICAL
TRANSCEIVER
a
typical
discrete
optical
Preliminary
2.13.2
The MCP2140 was designed to use a discrete imple-
mentation that allows the lowest system power con-
sumption and a low cost implementation (see
Section 2.12.1, “Discrete Transceiver Solution”). It is
possible to use an integrated optical transceiver solu-
tion, with the addition of four components. Two com-
ponents are required to condition the input signal to
ensure that the RXIR pulse width is not greater than
1.5 µs (see
ponents are required to set the RXIR signal trip point
(typically V
MCP2140 optical transceiver circuit, using a Vishay
Temic TFDS4500.
FIGURE 2-12:
Table 2-6
integrated optical transceivers.
+5 V
Note 1: These components are used to control
R13
47
C18
.1 µF
R14
10 k
R15
10 k
+5 V
2: These components are used to set the
(2)
(2)
shows a list of common manufacturers of
INTEGRATED TRANSCEIVER
DD
Parameter
the width of the TFDS4500 RXD output
signal. Q1 is a digital transistor, which
includes the bias resistors.
reference voltage that the RXPD signal
needs to cross to “detect” a bit.
/2).
68 pF
C19
1
2
3
4
TFDS4500
U6
Figure 2-12
(1)
CIRCUIT FOR AN
INTEGRATED OPTICAL
TRANSCEIVER
IR131A). The other two com-
+5 V
8
7
6
5
Q1
MUN211T1
MCP2140
R11
22
(1)
(To MCP2140 Pin 18)
(To MCP2140 Pin 1)
shows an example
(To MCP2140 Pin 2)
+5 V
DS21790A-page 17
RXPDREF
RXPD
TXIR
®
/