HEF40244?=20 Would need a level shifter as well. Limiting parameter will be Idd(max) so = maybe need more than one per digit. Seems to be an active part. Stephen > -----Original Message----- > From: piclist-bounces@mit.edu On Behalf Of > Dwayne Reid > Sent: Thursday, 7 March 2019 10:50 AM > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Looking for recommendation: high-side LED display drive= r >=20 > Hi there, Bob. >=20 > I'm glad that you commented on Mr Smiley's message - I did not receive th= at > message. >=20 > But you nailed it when you suggested that it won't work. Not only does e= ach > segment have three LEDs in series, but the display is direct-drive (no > multiplexing). The display connector has 37 connections. >=20 > That said - I wasn't aware of the TM1638. I'll keep it in mind for other > projects. >=20 > I have considered using 4- 74HC595 shift-register chips as a high-side dr= iver > by shifting the ground pin by 3.5 Vdc or so, then using simple level-shif= t > circuits for the data, clock, strobe pins. But the maximum package curre= nt for > the HC595 is 70mA and I want to drive the segments at 20mA each (140mA > total per package). >=20 > I also considered using the CD4511 decoder/driver chips that the original > manufacturer used. Downside with those is that I truly do NOT like the "= 6" > and "9" digits from the 4511 (top / bottom bar is > missing) **and** I can't send arbitrary segment patterns to the display > (HELP, OUCH, On, on, oFF, OFF, etc). You get the picture. >=20 > Sephro suggested just adding a whack of jellybean dual PNP transistors - = that > is still an option. >=20 > So - I'm still looking for suggestions. This doesn't need to be done now= but > we've been sitting on these displays for quite a while now and it would b= e > nice to make use of them. >=20 > Many thanks! >=20 > dwayne >=20 >=20 > At 01:29 PM 3/6/2019, Bob Blick wrote: > >OP needs to drive three LED in series strings. I don't think TM1638 > >work above 5V. The price is right though. > >Cheerful regards, Bob > >________________________________________ > >From: piclist-bounces@mit.edu on behalf of Mr > >Smiley > >Sent: Wednesday, March 6, 2019 11:28 AM > >To: piclist@mit.edu > >Subject: Re: [EE] Looking for recommendation: high-side LED display > >driver > > > >TM1638 > > > >:0) >=20 >=20 > -- > Dwayne Reid > Trinity Electronics Systems Ltd Edmonton, AB, CANADA > 780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free > www.trinity-electronics.com > Custom Electronics Design and Manufacturing >=20 > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .