U6812B Просмотр технического описания (PDF) - Atmel Corporation

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U6812B

Single-ended Bus Transceiver with Triple Buffer

Atmel Corporation 

U6812B

Application Note

Digital Inputs (DIS, IN 1,

IN 2, IN 3 and TxD)

It is recommended to use the external components as shown in Figure 3 on page 3 with

the reverse battery protection diode D1 and the buffer capacitor C1 = 10 µF.

The digital inputs are CMOS-compatible and equipped with a built-in pull-up resistor

with a typical rating of 85 kW to VCC. The input threshold totals VTH = 0.57 ´ VCC with a

typical hysteresis of 100 mV. The inputs are designed for an input voltage of -0.2 V to

VCC + 0.6 V.

For proper activation of the output stages, it is mandatory that the inputs are kept low as

long as the supply voltage is not applied. When the supply voltage has been applied, all

inputs need to have a falling edge (see “Timing Diagrams” on page 6).

Digital Output (RxD)

The digital output RxD is a push-pull output stage with a driver power of IRxD = 1 mA.

Interference Voltages

and Load Dump (Defined

in DIN40839 or ISO7637)

The U6812B is protected against interference pulses (usually present in the wiring) by

the recommended R1C1 circuitry and the integrated elements (28-V Z-diodes, both at

the supply pin and at the output pins and two diodes connected to VCC and GND at the

digital inputs). All transient pulses, which appear on the supply line (VBatt), should not

affect the function of the IC (see Table 1).

Table 1. Transient Test Conditions

Name

DIN/ISO 1

DIN/ISO 2

DIN/ISO 3a

DIN/ISO 3b

DIN/ISO 5

Voltage

-110 V

110 V

-160 V

150 V

55 V (total)

Source Resistance

10 W

10 W

50 W

50 W

2W

Rise Time

100 V/µs

100 V/µs

30 V/ns

20 V/ns

10 V/ms

Pulse Duration

2 ms

0.05 ms

0.1 µs

0.1 µs

500 ms

Pulse Amount

15000

15000

1 h (reference to ISO)

1 h (reference to ISO)

20

Table 2. Truth Table

WSI-1

WSI-2

WSI-R

EN

L

L

X

H

H

H

X

X

L

L

X

L

X

X

H

X

X

X

L

X

X

X

X

X

TXD

X

X

X

H

L

X

K

X

X

X

Open

L

H

WSO-1

L

Open

Open

X

L

X

WSO-2

L

Open

Open

X

X

X

WSO-R

X

X

X

Open

L

X

RXD

X

X

X

H

L

H

5

4760A–AUTO–10/03

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