LT1328CS8 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LT1328CS8' PDF : 12 Pages View PDF
LT1328
APPLICATIONS INFORMATION
1.152Mbps rate, for example, uses pulses of 217ns for its
bit time of 870ns. Light levels are 100mW/SR to 500mW/
SR over the 1cm to 1 meter range. A photo of a transmit-
ted input and LT1328 output is shown in Figure 3. The
LT1328 output pulse width will be less than 800ns wide
over all of the above conditions at 1.152Mbps. Pin 7
should be held low for these data rates and above.
The last IrDA encoding method is for 4Mbps and uses
pulse position modulation, thus its name 4ppm. Two bits
are encoded by the location of a 125ns wide pulse at one
of the four positions within a 500ns interval (2 bits •
1/500ns = 4Mbps). Range and input levels are the same as
for 1.152Mbps. Figure 4 shows the LT1328 reproduction
of this modulation.
IrDA-FIR (1m)
NRZ DATA
0
1
0
0
1
1
0
1
0
IrDA-FIR HIGH = LIGHT TRANSMITTED
DATA RATES: FIXED AT 1.15Mbps
BIT INTERVAL: 870ns
PULSE WIDTH: 1/4 OF INTERVAL OR 217ns
1328 F03a
IrDA-FIR (1cm)
RECEIVER
OUTPUT
TRANSMITTER
INPUT
RECEIVER
OUTPUT
TRANSMITTER
INPUT
Figure 3. IrDA-FIR Modulation
DATA BIT 4ppm DATA
NRZ DATA
PAIR
00
SYMBOL
1000
0
1
0
0
1
1
0
1
0
01
0100
IrDA 4ppm HIGH = LIGHT TRANSMITTED
10
0010
11
0001
DATA RATES: FIXED AT 4Mbps
BIT INTERVAL: 500ns
1328 F04a
PULSE WIDTH: 1/4 OF INTERVAL OR 125ns
IrDA-4ppm(1m)
IrDA-4ppm (1cm)
RECEIVER
OUTPUT
TRANSMITTER
INPUT
6
RECEIVER
OUTPUT
TRANSMITTER
INPUT
Figure 4. IrDA-4ppm
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