LT1328CS8 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LT1328CS8' PDF : 12 Pages View PDF
LT1328
APPLICATIONS INFORMATION
There is one drawback to the previous scheme. Lowering
the highpass frequency to 14Hz negates the normally
excellent ambient light rejection of the LT1328 to line-
operated light sources. By modulating the data in a very
simple and inexpensive way the ambient light rejection
can be maintained. The NRZ data is used to gate a 3MHz
square wave before driving the transmitter. The LT1328 in
FIR-4ppm mode (bandwidth of 1MHz to 4MHz) will re-
ceive the 3MHz signal. Thus, the low frequency response
is no longer required and the LT1328 can be configured as
a FIR receiver with no changes. Note that when in FIR/
4ppm mode, the LT1328 has excellent rejection to active-
ballast fluorescent lights (40kHz to 100kHz) as well as line
operated bulbs. The data is recovered with two stages of
retriggerable one-shots on the output of the LT1328. The
first one-shot pulse length is set to 80ns and acts as an
edge detector and the second one-shot pulse length is set
to 2.3µs, just under a symbol period. With this modula-
tion, the range can be extended to over 30" and still have
a bit error rate lower than 1 in 108.
5V
> 30"
C5
D2
4.7µF
HSDL 4220
R3
3.9Ω
1/2W
R1
100Ω
Q3
2N7002
R2
10k
74LS00
3
2
1
BIT ERROR RATE
TRANSMITTER/RECEIVER
375bps NRZ DATA
OUT
IN
3MHz
D1
TEMIC
BPV22NF
1
8
2
7
3
LT1328
6
NC
C4
4
5
100pF
C6
1000pF
5V
C2
4.7µF
C8
100pF
R5
46.4k 5V
1%
6
7
11
5 1/2 10
74LS123
9
R4
C7
5k
10pF
1%
15
14
1
13 1/2 2
74LS123
3
1328 F06
Figure 6. Simple Data Link with Improved Low Frequency Noise Rejection
TYPICAL APPLICATIONS N
Wireless Slave for Photographic Flash
LIGHT FROM
MASTER FLASH
R1
100Ω 1
D1
HAMAMATSU
2
S4797-01
C4
330pF
3
NC
4
LT1328
8
NC
7
NC
6
R2
5
1k
D2
1N4148
TO HOT SHOE
OF SLAVE FLASH
5V
R3
10k Q1
C2
R5
4.7µF 1k
MPS2907A
Q2
MPSA42
R4
10k
C5
0.1µF
D3
MUR
160524
1328 TA05
8
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