Hypex SMPS DC Error detection and DC blocking cap bypass - diyAudio
Go Back   Home > Forums > Amplifiers > Class D
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 7th January 2011, 08:15 AM   #1
diyAudio Member
Join Date: Nov 2010
Default Hypex SMPS DC Error detection and DC blocking cap bypass

Hi Hypex enthousiasts,

I'm currently building my miniDSP based crossover integrated in a slim-line case with single Hypex SMPS400A180 switching mode power supply, feeding four Ucd180HG modules. This will be directly feeding the drivers in my Linkwitz Pluto speakers.

I have two questions:
The SMPS400A180 contains two DC Error monitoring inputs (J6 pin 1 and 2) each to connect to LS+ terminal of two attached UcD modules. Following the datasheet, when DC is detected on either of this inputs, SMPS will switch to Standby mode quickly to protect speakers. This is fine, however I would like to monitor (and protect) four UcD modules. Is there a recommended way to achieve this? I was thinking of connecting two Ucd's LS+ output's per "DC Error Input" by e.g. 10k resistors in series? Would this work? If in this situation, one UcD would fail and the full rail voltage would be present on the LS+ (worst case), this config would act as a voltage divider and only half that voltage would be sensed. Would this still work? Is there a treshold to the DC detection limit? Any other ideas to really select "max out of two"?

My second question is about (a future tweak) bypassing one of both DC blocking caps in each of my four signal paths. Since the DAC's in the miniDSP have DC on their outputs, these are blocked on the miniDSP print as well. So I have a choice to bypass on the UcD input circuit or at the miniDSP print. Since I am digitally attenuating at the miniDSP, only signal cable is between the outputs of the miniDSP and UcD inputs.
Bypassing which cap would yield the biggest sonic improvement?
miniDSP is using "Nichicon Audiophile capacitors" according to their datasheet, while the Ucd180HG modules are also using Audiograde types, I don't know the brand/type, value is 684nF, OM3 is listed on the caps, nothing more. They are designated C1 and C2, (colored dark-red) left site of the input pins if I'm correct?

Would appreciate any suggestions!

gtrz, Maarten
  Reply With Quote
Old 7th January 2011, 10:06 AM   #2
diyAudio Member
meanman1964's Avatar
Join Date: Oct 2006
Location: Belgium the land of chocolate
Maarten did you asked this question at zelfbouwaudio.nl?
  Reply With Quote
Old 7th January 2011, 10:15 AM   #3
diyAudio Member
Join Date: Nov 2010
No, why?
  Reply With Quote
Old 7th January 2011, 10:23 AM   #4
diyAudio Member
Join Date: Feb 2005
Location: Antwerp
I asked the same question to hypex directly.

I worked around the problem in another way, but if you look on the downside of the DC protection pins, you'll that it's already 2 big resistors (I think 10K) per input leading to the same trace on the pcb. it's SMC, but according to hypex you can just add another 10K resistor to add a third DC protection.
  Reply With Quote
Old 7th January 2011, 10:58 AM   #5
diyAudio Member
Join Date: Nov 2010
Yves, thanks!

So when I need to monitor DC of 4 UcD's, 2 adittional R10k resistors could be soldered to the joining location of the 2 existing SMD resistors attached to J6_1:2? That would at least give a symmetrical situation, only sensed DC would be divided by 4 (instead by 2 as in the original design already foreseen). The thing I'm worries about is whether the protection is designed to become active only if a rail voltage is sensed or that it would be triggered ealier. If the latter is the case I might be fine I think!

Any ideas, comments?

regards, Maarten
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Adcom GFA-555 Feedback DC-Blocking Cap? EchoWars Pass Labs 14 14th April 2010 07:12 PM
The 'Ci' DC blocking cap in the LM3886 Feedback Loop speakerguy79 Chip Amps 9 29th June 2009 06:03 PM
Parafeed dc blocking/coupling cap help nhuwar Tubes / Valves 6 29th March 2009 03:44 PM
DC blocking cap in feedback path or DC servo? roender Solid State 27 19th September 2007 09:40 AM
Large Value Cap For DC Blocking KYMcJerry Parts 4 9th February 2003 11:30 PM

New To Site? Need Help?

All times are GMT. The time now is 06:28 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2