22

LTC1402

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

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

100

Ω

100

Ω

100

Ω

100

Ω

100

Ω

100

Ω

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

10

µF

CONV

SCK

OGND

11

16

15

10

9

3

4

LTC1402

2

1

7

6

10

9

8

11

5

3

16

GND

BFSR

BCLKR

BDR

TMS320C54x