Lpc2000

For 74AC08 you can have "Outputs source/sink 24 mA",
http://www.fairchildsemi.com/pf/74/74AC08.html

Adrian

--- Tom Walsh <tom@...> wrote:

> Ed Schlunder wrote:
> 
> >I'm thinking of building the DIY wiggler so that I
> can program and
> >debug some LPC2103 chips on the cheap.
> >
> >I see the wiggler.txt schematic in the files area.
> It is using a
> >74AC244 chip to do voltage level conversion between
> the PC and the
> >LPC21xx chip. It only seems to use 4 line drivers
> of the 74AC244 chip
> >(half the chip is left unused). 
> >
> >Would there be any problem with using a 74VHC08
> quad 2 input AND gate
> >chip instead? I would just tie one side of each AND
> gate high so that
> >it can be used as 4 line drivers. This chip is
> cheaper and smaller
> >than the 74AC244.
> >
> >  
> >
> However, it may not have the same drive levels
> (output current).  The 
> '244 series is a buffer / driver, typically
> producting 12ma sink and 4ma 
> source.  The '08 is a logic device, not a driver, 
> you will probably 
> only find that it can do +/- 4ma (if you are lucky).
> 
> Output impedance would dictate how quickly signals
> may be driven high / 
> low on the JTAG interface.  Too high an impedance ==
> lousy signal edges 
> / ring / overshoot.
> 
> TomW
> 
> 
> -- 
> Tom Walsh - WN3L - Embedded Systems Consultant
> http://openhardware.net, http://cyberiansoftware.com
> "Windows? No thanks, I have work to do..."
> ----------------------------------------------------
> 
> 
> 


Adrian Valeanu.
SC PROSAFE SRL
J/40/11835/2002 ; CUI 15026939
Aleea Politehnicii nr. 2
Bl. 5A, sc. 1 Ap. 17 Sector 6, BUCHAREST
ROMANIA
Tel/fax +40 (21) 781.38.58

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