LTC1535

4

1535fb

ELECTRICAL CHARACTERISTICS

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Data Sample Jitter

Figure 8, (Note 7)

l

250

285

ns

Max Baud Rate

Jitter = 10% Max, SLO = 1, (Note 8)

l

250

410

kBd

Driver Input to Output

DE = 1, SLO = 1, Figure 4, Figure 6

DE = 1, SLO = 0, Figure 4, Figure 6

l

l

600

1300

855

1560

ns

ns

Driver Input to Output

DE = 1, SLO = 1, Figure 4, Figure 6

DE = 1, SLO = 1, Figure 4, Figure 6

l

l

600

1300

855

1560

ns

ns

Driver Rise or Fall Time

DE = 1, SLO = 1, Figure 4, Figure 6

l

l

150

20

500

100

1000

ns

ns

Driver Enable to Output

DI = 1, SLO = 1, Figure 5, Figure 7

l

1000

1400

ns

Driver Enable to Output

DI = 0, SLO = 1, Figure 5, Figure 7

l

1000

1400

ns

Driver Disable to Output

DI = 0, SLO = 1, Figure 5, Figure 7

l

700

1300

ns

Driver Disable to Output

DI = 1, SLO = 1, Figure 5, Figure 7

l

700

1300

ns

Receiver Input to RO

RE = 0, Figure 3, Figure 8

l

600

855

ns

Receiver Input to RO

RE = 0, Figure 3, Figure 8

l

600

855

ns

Receiver Input to RO2

RE = 0, Figure 3, Figure 8

30

ns

Receiver Input to RO2

RE = 0, Figure 3, Figure 8

30

ns

Receiver Rise or Fall Time

RE = 0, Figure 3, Figure 8

20

ns

Receiver Disable to Output

Figure 3, Figure 9

30

ns

Receiver Disable to Output

Figure 3, Figure 9

30

ns

Initial Start-Up Time

(Note 9)

1200

ns

Data Time-Out Fault

(Note 9)

1200

ns

ST1, ST2 Duty Cycle

l

l

56

57

%

%

The

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 2: RS422 50Ω specification based on RS485 27Ω test.

Note 4: Input fault conditions on the RS485 receiver are detected with a

fixed receiver offset. The offset is such that an input short or open will

result in a high data output.

through the weak driver output on RE.

Note 6: Value derived from 1 second test.

Note 7: The input signals are internally sampled and encoded. The internal

sample rate determines the data output jitter since the internal sampling is

asynchronous with respect to the external data. Nominally, a 4MHz internal

sample rate gives 250ns of sampling uncertainty in the input signals.

Note 8: The maximum baud rate is 250kBd with 10% sampling jitter.

Lower baud rates have lower jitter.

Note 9: Start-up time is the time for communication to recover after a fault

condition. Data time-out is the time a fault is indicated on RE after data

communication has stopped.