TXD

DTO

RXD

DTO

Thermal

Shutdown

FAULT

GND

UV

Lockout

µP

FAULT

Input

SN65HVD255

SN65HVD256, SN65HVD257

SLLSEA2C – DECEMBER 2011 – REVISED SEPTEMBER 2013

www.ti.com

Undervoltage Lockout

The supply pins have undervoltage detection that places the device in protected mode. This protects the bus

Table 4. Undervoltage Lockout 5V Only Devices (SN65HVD255 and SN65HVD257)

DEVICE STATE

BUS OUTPUT

RXD

GOOD

Normal

Per Device State and TXD

Mirrors Bus

BAD

Protected

High Impedance

High Impedance (3-state)

DEVICE STATE

BUS OUTPUT

RXD

GOOD

GOOD

Normal

Per Device State and TXD

Mirrors Bus

BAD

GOOD

Protected

High Impedance

High (Recessive)

GOOD

BAD

Protected

Recessive

High Impedance (3-state)

BAD

BAD

Protected

High Impedance

High Impedance (3-state)

APPLICATION NOTE: After an undervoltage condition is cleared and the supplies have returned to valid

levels, the device typically resumes normal operation in 300 µs.

FAULT Pin (SN65HVD257)

If one or more of the faults (TXD-Dominant Timeout, RXD dominant Timeout, Thermal Shutdown or

Undervoltage Lockout) occurs, the FAULT pin (open-drain) turns off, resulting in a high level when externally

Figure 5. FAULT Pin Function Diagram and Application

6

Submit Documentation Feedback

Copyright © 2011–2013, Texas Instruments Incorporated

Product Folder Links: SN65HVD255 SN65HVD256 SN65HVD257