PCLT-2A

6 Unisolated ASI-interface bus application diagram

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6.3

Un-isolated connection of the PCLT with AS-Interface

controller

To remove the opto-coupler the operation of the PCLT has been extended to fit the AS-Interface

application. A precaution is required on its interface with the bus controller: the impedance

between the two circuits must be high in order to maintain the impedance isolation.

Zener diode reference fed from the sensor bus.

Because of the buffer voltage increase, it becomes possible to insert high impedance between

the PCLT output and the AS-Interface bus controller input. Typically a 100k

Ω resistor is

designed while keeping a 5 V CMOS operation on the input of the bus controller.

Figure 14 shows the application diagram where the PCLT is connected to the slave bus

controller through a 100 k

Ω resistor. The logic signal is transmitted with a low level of less than

buffer limiting its current to 35 µA minimum and the 100 k

Ω pull down resistor (0.035 mA times

100 k

Ω).

Figure 14. AS-Interface slave controller unit using the PCLT in an un-isolated manner.

10

12V

SLAVE AS-I

CONTROLLER

V

CC

28V

1

PCLT2

750

7

14

9

V

CCsensor

sensor

Vreg

ASiP

ASiN

30V

10

12V

SLAVE AS-I

CONTROLLER

V

CC

28V

1

PCLT2

750

Ω

7

14

9

V

CCsensor

sensor

Vreg

ASiP

ASiN

30V