of nodes on one bus. In a single master multi-slave type of

application where the number of slaves exceeds 32, the

DS481 may save in the cost of extra devices like repeaters,

extra media like cable, and/or extra components like resis-

tors.

Sleep Mode

The DS481 features an automatic sleep mode that allows

the device to save power when not transmitting data. Since

the sleep mode is automatic, no external components are

required. It may be used as little or as much as the applica-

tion requires. The more the feature is utilized, the more

power it saves.

The sleep mode is automatically entered when both the

driver and receiver are disabled. This occurs when both the

DE pin is asserted to a logic low and the RE (Note 1) pin is

asserted to a logic high. Once both pins are asserted the

device will enter sleep mode after 50 ns. The DS481 is

guaranteed to go into sleep mode within 600 ns after both

pins are asserted. The device wakes up (comes out of sleep

mode) when either the DE pin is asserted to a logic high

and/or the RE (Note 1) pin is asserted to a logic low. After the

device enters sleep mode it will take longer for the device to

wake up than it does for the device to enable from TRI-

STATE. Refer to datasheet specifications t

compare with t

The benefit of the DS481 is definitely its power savings.

When active the device has a maximum I

When in sleep mode the device has a maximum I

10 µA, which is 50 times less power than when active. The

I

sleep mode the I

Applications Information

Multipoint RS-485 Application

01291917

01291916

FIGURE 15. Input Current vs Input Voltage

Operating Range

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