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Infrared Remote Control Transmitter
PT2248
FUNCTION DESCRIPTION
OSCILLATION CIRCUIT
When the self-bias type amplifier is housed by CMOS inverter method, the oscillation circuit can be
constructed when a ceramic resonator has been connected.
Rf
2
3
Cer am ic Res on ator
45 5K Hz
C1 , C2 = 120 pF ~ 150p F
C1
C2
When the oscillation frequency is set at 455KHz, the carrier wave of the transmitting signal is set at
38KHz. Unless the keys are being operated, the oscillation is normally stopped; thereby, reducing
power consumption.
KEY INPUT
18 Keys can be connected by Key Inputs K1 ~ K6 and timing signals T1 ~ T3.
Multiple Keying (maximum of 6 keys) is possible for the keys connected to T1 line (Output becomes
continuous pulses).
The order of priority of the timing signal line is T1, T2, and T3. When 2 or more keys that are connected
to T2 (or T3) line are pressed simultaneously, the single output will have the preferential order of K1 ~
K6.
Furthermore, the keys connected to T2 and T3 lines are for single signals and no second signal is
transmitted unless input is made after the key is released once.
PT2248 V2.7
-4-
June, 2005
PTC [ PRINCETON TECHNOLOGY CORP ]
