4

LTC1535

POWER SIDE

tor.

ST1 (Pin 2): DC Converter Output 1 to DC Transformer.

ST2 (Pin 3): DC Converter Output 2 to DC Transformer.

GND (Pin 4): Ground.

DI (Pin 25): Transmit Data TTL Input to the Isolated Side

RS485 Driver. Do not float.

DE (Pin 26): Transmit Enable TTL Input to the Isolated

Side RS485 Driver. A high level enables the driver. Do not

float.

RE (Pin 27): Receive Data Output Enable TTL Input. A low

level enables the receiver. This pin also provides a fault

output signal. (See Applications Information.)

RO (Pin 28): Receive Data TTL Output.

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

life of a device may be impaired.

Note 2: RS422 50

Ω 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.

and reenables when greater than 4.4V. The fault can be monitored

through the weak driver output on RE.

Note 6: Value derived from 1 second test.

ISOLATED SIDE

GND2 (Pin 11): Isolated Side Power Ground.

Z (Pin 12): Differential Driver Inverting Output.

Y (Pin 13): Differential Driver Noninverting Output.

Bypass to GND with 10

µF capacitor.

B (Pin 15): Differential Receiver Inverting Input.

A (Pin 16): Differential Receiver Noninverting Input.

RO2 (Pin 17): Isolated Side Receiver TTL Output.

SLO (Pin 18): Slow Slew Rate Control of RS485 Driver. A

low level forces the driver outputs into slow slew rate

mode.

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 350kBd 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.

PI FU CTIO S

ELECTRICAL CHARACTERISTICS