National's mistake (AN-1192)?

cm961 · 15th December 2003, 05:04 AM

Hey guys,

I was reading National's AN-1192 again (like anyone here hasn't read it). Anyway, I'm confused about the voltage regulators for the input stage op-amp. They're using LM78L15s and LM79L15s which have a maximum input voltage of 23V. But the supply voltage is 42V. Soo..... wouldn't the regulators blow up?

If I'm right, then what do people use to lower the main supply to an acceptable level for op-amps (NE5532s in my case)? My rail supplies are +- 28V.

Pete

mozikluv · 15th December 2003, 06:50 AM

i think the said regulator has a max. input of 35v and a min. of 16v with a current output of 100ma.

i have seen the literature of the 1192 but have not really scrutyinize the schem. the only thing that interested me was the interconnection of the bridge/parallel circuit. IC audio power amps is not my cup of tea.

mozikluv · 15th December 2003, 07:27 AM

hi,

now i've seen the an1192 literature again. according to specs. if you want to drive a 4 ohm load you power it with +/-28v. if for 8ohms load you power that with +/-35v. now this voltages are all within the specs of the 78L15

UrSv · 15th December 2003, 07:28 AM

The maximum input is depending on manufacturer but AFAIK none has a maximum of 23 V input. The National version of LM7815 has a maximum input of 35 V. The 23 V specified in the datasheet is the figure used when measuring the specs listed if I'm not making a mistake.

peranders · 15th December 2003, 07:36 AM

cm961, allways look at "absolute maximum ratings" in the datasheet. Have you done that?

35 volts is the normal value.

cm961 · 15th December 2003, 03:03 PM

Thanks for clearing that up guys, I was very very confused. I guess I shouldn't design circuits at 2:30am...

Thanks again,
Pete

15th December 2003, 05:04 AM	#1
cm961 diyAudio Member Join Date: Jun 2001 Location: Peterborough, Ontario	National's mistake (AN-1192)? Hey guys, I was reading National's AN-1192 again (like anyone here hasn't read it). Anyway, I'm confused about the voltage regulators for the input stage op-amp. They're using LM78L15s and LM79L15s which have a maximum input voltage of 23V. But the supply voltage is 42V. Soo..... wouldn't the regulators blow up? If I'm right, then what do people use to lower the main supply to an acceptable level for op-amps (NE5532s in my case)? My rail supplies are +- 28V. Pete

15th December 2003, 06:50 AM	#2
mozikluv diyAudio Member Join Date: Aug 2003 Location: Bacolod City, Neg. Occ., Philippines	lm78l15acz i think the said regulator has a max. input of 35v and a min. of 16v with a current output of 100ma. i have seen the literature of the 1192 but have not really scrutyinize the schem. the only thing that interested me was the interconnection of the bridge/parallel circuit. IC audio power amps is not my cup of tea. __________________ "none but the brave deserves the fair" shakespeare

15th December 2003, 07:27 AM	#3
mozikluv diyAudio Member Join Date: Aug 2003 Location: Bacolod City, Neg. Occ., Philippines	lm78l15acz hi, now i've seen the an1192 literature again. according to specs. if you want to drive a 4 ohm load you power it with +/-28v. if for 8ohms load you power that with +/-35v. now this voltages are all within the specs of the 78L15 __________________ "none but the brave deserves the fair" shakespeare

15th December 2003, 07:28 AM	#4
UrSv diyAudio Member Join Date: Jan 2002 Location: Sweden	The maximum input is depending on manufacturer but AFAIK none has a maximum of 23 V input. The National version of LM7815 has a maximum input of 35 V. The 23 V specified in the datasheet is the figure used when measuring the specs listed if I'm not making a mistake. __________________ UrSv Those who say it can't be done should not stop those who are doing it.

15th December 2003, 07:36 AM	#5
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	cm961, allways look at "absolute maximum ratings" in the datasheet. Have you done that? 35 volts is the normal value. __________________ /Per-Anders (my first name) or P-A as my friends call me


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15th December 2003, 03:03 PM	#6
cm961 diyAudio Member Join Date: Jun 2001 Location: Peterborough, Ontario	Thanks for clearing that up guys, I was very very confused. I guess I shouldn't design circuits at 2:30am... Thanks again, Pete

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