Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

DALI signal bus voltage is widely variant?

Status
Not open for further replies.
T

treez

Guest
The DALI bus is said to be 0V to 16V nominal
However, the “High” voltage can be anywhere from 9V5 to 22V5.

Is this really so? Is it seriously that poor in tolerance?
It makes designing a opto based DALI receiver so much more problematic in terms of needing optocouplers and associated circuitry which can manage the wide range of currents that one gets due to this wide bus range.
What percentage of DALI PSU’s give a voltage outside 16+/-1V for the DALI bus?

DALI bus
https://en.wikipedia.org/wiki/Digital_Addressable_Lighting_Interface
 

From the link:
DALI wires can be connected to a device without regard for polarity. Signal level are defined as 0±4.5 V for "0" and 16±6.5 V for "1"
What it is really defining is the "no mans land" region. The upper voltage threshold for a logic "0" is 4.5V and the lower threshold for a logic "1" is 9.5V (16-6.5). The 22.5V is a maximum high before going into the over-voltage danger region. How high any individual device would tolerate is up to it's designer but it has to be safe up to at least 22.5V to meet DALI spec.

Brian.
 

Is this really so? Is it seriously that poor in tolerance?

DALI provides data and power supply over the same line, and cable length can be rather large, so that voltage drop can be significant and far away devices operate at much less than the nominal DC supply voltage.

For voltage levels on transmitter and receive side (different!), see page 18 of the DALI manual
**broken link removed**
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top