Texas Instruments TMS3637P, Data Manual

Page: 37 / 53

6–5
OSCR OSCC TIME GND
VCC IN CEX OUT
U1 (transmitter)
VCC CODE GND CLK
Figure 6–3. Four-Wire Direct Connection Key
6.3 Infrared Coupling of Transmitter/Receiver — Normal Transmission Mode
Table 6-3 lists the parts for the schematic of an infrared transmitter working in the normal transmission
configuration as shown in Figure 6–4. Table 6–4 lists the parts for the infrared receiver shown in Figure 6–5.
The transmitter is configured as a normal continuous transmitter, and the content of the configuration
EEPROM cells is:
CA CB CC CD CE CF CG CH CI
1 1 1 0 0 0 0 0 0
The transmitter uses its internal oscillator to clock the data out. The frequency of the oscillator is
approximately 26 kHz.
The receiver is configured as a logic normal (1-code) Q-state inverting receiver and the content of the
EEPROM cells is:
CA CB CC CD CE CF CG CH CI
0 1 0 0 0 1 0 0 1
The receiver is used in the inverting mode. The code is considered to be inverted when using OUT on the
transmitter to transmit the code. The signal path between the transmitter and receiver does not invert the
signal. Using the logic mode (CF = 1) also does not invert the signal. The result is a signal that is inverted
at the internal logic controller of the receiver, then use CI = 1 for an inverting receiver.
As required, the oscillating frequency of the receiver is 260 kHz, which is approximately ten times greater
than that of the transmitter. This is provided by the internal oscillator in the receiver. OUT on the receiver
maintains the same status for approximately 0.5 seconds (1M
×
470 nF).