Datasheet

22
LTC1402
TYPICAL APPLICATION
U
Using Quad Cable Drivers/Receivers in Remote
LTC1402 Applications
In some applications, the host controller or main proces-
sor may be located some distance from the sensor, the
signal conditioning circuitry, and the ADC. In these appli-
cations, maintaining serial data integrity over long cable
distances can be a challenge. The circuit in Figure 15
shows one way to convey the LTC1402’s high-speed serial
data over a long distance. The circuit uses the LTC1688
quad cable driver and an LTC1520 quad cable receiver to
transmit/receive the LTC1402’s high-speed 35.2Mbps
serial data to the DSPs serial port over category-5
unshielded cable. Using these devices, the LTC1402’s
serial data can be transmitted up to 100 feet without data
corruption. Because the SCK, CONV and D
OUT
signals
originate at the LTC1402, they arrive at the serial port with
similar delays and remain synchronized. When the data is
received at the serial port of the DSP or other controller,
the port must be programmed to respond to the appropri-
ate SCK and CONV edges. It is also necessary to check
where the 12-bit output DATA resides in the 16-bit data
frame. The TMS320C54x serial port READ instructions
can shift the 12-bit data to the preferred position within the
16-bit data frame.
Figure 15. The LTC1402 3-Wire Serial Port Sends Data Over 100 Feet of Category-5
Twisted Pair with the LTC1688/LTC1520 Quad Driver/Receiver Pairs
100Ω100Ω
100Ω100Ω
100Ω100Ω
SIGNAL
CONV
2.2Msps
CLK
35.2MHz
LTC1688
QUAD DRIVER
LTC1520
QUAD RECEIVER
PIN 4 = ENA
PIN12 = ENB
CATEGORY-5
UNSHIELDED CABLE
UP TO 100 FEET
REMEE PART NO.
5A244UTPM30BU
14
14
15
4
4
15
12
13
13
1
7
9
8
2
3
6
5
10
11
16
5V
5V
10µF
0V
DD
CONV
SCK
D
OUT
OGND
11
16
15
10
9
A
IN
+
A
IN
–
DV
DD
3
4
LTC1402
2
1
7
6
10
9
8
11
5
3
16
V
DD
GND
BFSR
BCLKR
BDR
TMS320C54x