There is an LM-324V which is the low-voltage version of the chip. It is rated forrail-to-rail operation and has symetric source-sink capability. I do not have the data sheet here, but it is on the National web site ---- I have used the chip with good results in circuits where pulling within 50-100mVolts of the supply rails is important. It can only source/sink about 5-7 mA, do the high and low voltages depend on the load you put on it. Roy ----- Original Message ----- From: "Peter L. Peres" To: Sent: Monday, January 05, 2004 4:27 PM Subject: Re: [EE:] LM324 as schmidt trigger > >>Sorry for being cryptic. The LM324 will not pull the output down to GND > >>(it cannot sink current when this happens). Therefore a hysteresis > >>positive feedback resistor cannot be used when the input is only 65mV > >>unless a pulldown is used at the output of the LM324. > > > > Really? > > National LM324 datasheet (ed. 1994) p.5 graph "Output Characteristics, > Current Sinking", 5V supply line crosses the abscissa at about 10mV, 1uA > sink. This is 10kOhms Ro without a load or a wire attached, and it gets > worse with lower output voltage. > > Same datasheet, p.8 "Driving TTL" shows what needs to be done to achieve > Vil for a TTL chip input (which sources much less than a mA). A TTL > compatible CMOS input will not need such a strong pulldown, but with a > wire of some length attached, some noise, a scope probe, and pretensions > to make the hysteresis work as expected while pushing the frequency up > towards 1kHz a pulldown is required imho. Maybe 240 ohms is drastic. > > The same datasheet contains a number of applications which some will find > useful. > > Peter > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body