THVD1450: How to handle unused pins

This device has integrated pull-up/-down resistors; all unused pins can be left open (see section 9.4.3 of the datasheet).

If you have a very noisy environment and fear that the resistors might pick up noise, you can connect DE to GND and D and RE to V_CC.

Y.Ottey,

You can deactivate either function of the device using the DE and RE pins. Leaving DE floating would disable the driver, as an internal pull-down resistor would bring this to a logic low.

Similarly, leaving RE floating would disable the receiver, as an internal pull-up resistor would bring this to a logic high.

I rarely recommend putting floating input pins into a design, so if either portion of the device is to be disabled, I recommend pulling the DE or RE pin to V_CC or GND as applicable.

I especially recommend considering a pull-down for DE if the driver is not used. If a noisy environment somehow causes the driver to become temporarily enabled, it could cause bus contention or data corruption even if D is also left floating.

Unused digital outputs (pin R) can be left unconnected if necessary.

Best,

Danny

Y.Ottey,

Y.Ottey said:

(1) Connection of R and RE pins when using only the driver part of THVD1450

• R pin ⇒ floating
• RE pin ⇒ floating or connected to GND

(2) Connection of D and DE pins when using only the receiver part of THVD1450

• D pin ⇒ floating
• DE pin ⇒ Floating or connecting to VCC

Looks like we agree. The open RE pin disables the receiver, and the open DE pin disables the driver.

Best,

Danny