On Tuesday, May 19, 2020 at 7:12:42 AM UTC-7, jla...@highlandsniptechnology.com wrote:> IC data sheets used to include internal schematics. Now you have to > test or guess or ask on a forum, so someone else can guess for you.More than just schematics; the mustard TTL databook had schematics that actually were also layout topologies; no wires ever crossed unless they went in/out of a transistor base (the base diffusion was a cross-under conductor or a resistor, depending on which you needed).
why do they do this?
Started by ●May 18, 2020
Reply by ●May 19, 20202020-05-19
Reply by ●May 19, 20202020-05-19
On Tuesday, May 19, 2020 at 1:08:33 AM UTC-4, Bill Sloman wrote:> On Tuesday, May 19, 2020 at 2:01:09 PM UTC+10, jla...@highlandsniptechnology.com wrote: > > On Mon, 18 May 2020 17:57:06 -0700 (PDT), > > bloggs.fredbloggs.fred@gmail.com wrote: > > > > >On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > > >> ST makes a nice little LDO, super-low dropout with an aux Vbias > > >> supply. Saves me from rolling my own with an opamp and a mosfet. > > >> > > >> It's an ST1L08. > > >> > > >> So why is the data sheet file en.DM00123507.pdf ? > > > > > >Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > > > > Lying? It's all over the data sheet. It's how they get the millivolts > > of dropout. I do that when I make my own super-LDOs, power an opamp > > from some higher voltage and over-drive an nfet follower down to > > milliohms of Rds-on. > > > > >The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > > > > > > > I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > > would be 0.24 watts dissipated. Actually, I don't need that much > > current to run a couple DRAM chips. > > > > You sure are in a bad mood lately. > > He's gradually working out that he's in the one country where Covid-19 is eventually going to have a good chance at killing him, and that he's in the age group where it's quite likely to succeed. > > He can do all the wishful thinking he likes but the realisation that that's what's going to happen is gradually creeping up on him, and he doesn't like it at all.Okay- so you can now add psychology to all your other disqualifications.> > -- > Bill Sloman, Sydney
Reply by ●May 19, 20202020-05-19
On Tuesday, May 19, 2020 at 9:50:43 AM UTC-4, jla...@highlandsniptechnology.com wrote:> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > > >On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >> bloggs.fredbloggs.fred@gmail.com wrote: > >> > >>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >>>> > >>>> It's an ST1L08. > >>>> > >>>> So why is the data sheet file en.DM00123507.pdf ? > >>> > >>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >> > >> Lying? It's all over the data sheet. It's how they get the millivolts > >> of dropout. I do that when I make my own super-LDOs, power an opamp > >> from some higher voltage and over-drive an nfet follower down to > >> milliohms of Rds-on. > >> > >>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >>> > >> > >> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >> would be 0.24 watts dissipated. Actually, I don't need that much > >> current to run a couple DRAM chips. > >> > > > >Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >drop-out. 16 different fixed output voltages from 2.1V to 12V > >with 3% tolerance. As usual with products originating in the > >East, the datasheet is rather sparse about details, but I've used > >them and they do what I want. > > Is it stable with low ESR caps? We use polymers or ceramics mostly. > > We need so many goofy voltages that we usually buy adjustable > regulators for stock. The board that I'm doing now has a 24-channel > analog mux to BIST the power supplies, using the dreadful Xilinx > 1-volt XADC that's inside their FPGAs. Free and worth it. > > > > >> You sure are in a bad mood lately. > >> > >I've noticed that lately with some regulars here, including a few > >who normally exhibit decent manners. > > Well, some never show any sign of manners. They are repulsive but > you've got to feel sorry for them, stuck being around themselves all > day. > > There's a basically perfect -1 correlation between being obnoxious and > designing electronics.Seriously! Rigging up your little pseudo-LDO is not "designing" electronics. That's like saying figuring the part number suffix for the fixed 1.5V output is "designing" electronics.> > > > -- > > John Larkin Highland Technology, Inc > > Science teaches us to doubt. > > Claude Bernard
Reply by ●May 19, 20202020-05-19
On Wednesday, May 20, 2020 at 1:01:07 AM UTC+10, bloggs.fre...@gmail.com wrote:> On Tuesday, May 19, 2020 at 1:08:33 AM UTC-4, Bill Sloman wrote: > > On Tuesday, May 19, 2020 at 2:01:09 PM UTC+10, jla...@highlandsniptechnology.com wrote: > > > On Mon, 18 May 2020 17:57:06 -0700 (PDT), > > > bloggs.fredbloggs.fred@gmail.com wrote: > > > > > > >On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > > > >> ST makes a nice little LDO, super-low dropout with an aux Vbias > > > >> supply. Saves me from rolling my own with an opamp and a mosfet. > > > >> > > > >> It's an ST1L08. > > > >> > > > >> So why is the data sheet file en.DM00123507.pdf ? > > > > > > > >Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > > > > > > Lying? It's all over the data sheet. It's how they get the millivolts > > > of dropout. I do that when I make my own super-LDOs, power an opamp > > > from some higher voltage and over-drive an nfet follower down to > > > milliohms of Rds-on. > > > > > > >The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > > > > > > > > > > I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > > > would be 0.24 watts dissipated. Actually, I don't need that much > > > current to run a couple DRAM chips. > > > > > > You sure are in a bad mood lately. > > > > He's gradually working out that he's in the one country where Covid-19 is eventually going to have a good chance at killing him, and that he's in the age group where it's quite likely to succeed. > > > > He can do all the wishful thinking he likes but the realisation that that's what's going to happen is gradually creeping up on him, and he doesn't like it at all. > > Okay- so you can now add psychology to all your other disqualifications.That was comedy, not psychology. Fred didn't get the joke. -- Bill Sloman, Sydney
Reply by ●May 19, 20202020-05-19
On Tuesday, May 19, 2020 at 11:50:43 PM UTC+10, jla...@highlandsniptechnology.com wrote:> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > > >On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >> bloggs.fredbloggs.fred@gmail.com wrote: > >> > >>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >>>> > >>>> It's an ST1L08. > >>>> > >>>> So why is the data sheet file en.DM00123507.pdf ? > >>> > >>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >> > >> Lying? It's all over the data sheet. It's how they get the millivolts > >> of dropout. I do that when I make my own super-LDOs, power an opamp > >> from some higher voltage and over-drive an nfet follower down to > >> milliohms of Rds-on. > >> > >>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >>> > >> > >> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >> would be 0.24 watts dissipated. Actually, I don't need that much > >> current to run a couple DRAM chips. > >> > > > >Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >drop-out. 16 different fixed output voltages from 2.1V to 12V > >with 3% tolerance. As usual with products originating in the > >East, the datasheet is rather sparse about details, but I've used > >them and they do what I want. > > Is it stable with low ESR caps? We use polymers or ceramics mostly. > > We need so many goofy voltages that we usually buy adjustable > regulators for stock. The board that I'm doing now has a 24-channel > analog mux to BIST the power supplies, using the dreadful Xilinx > 1-volt XADC that's inside their FPGAs. Free and worth it. > > > > >> You sure are in a bad mood lately. > >> > >I've noticed that lately with some regulars here, including a few > >who normally exhibit decent manners. > > Well, some never show any sign of manners. They are repulsive but > you've got to feel sorry for them, stuck being around themselves all > day. > > There's a basically perfect -1 correlation between being obnoxious and > designing electronics.And John Larkin likes to think that he "designs" his electronics so he's just flattering himself. -- Bill Sloman, Sydney
Reply by ●May 19, 20202020-05-19
On Tue, 19 May 2020 08:04:52 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com wrote:>On Tuesday, May 19, 2020 at 9:50:43 AM UTC-4, jla...@highlandsniptechnology.com wrote: >> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >> >> >On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >> >> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >> >> bloggs.fredbloggs.fred@gmail.com wrote: >> >> >> >>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >> >>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >> >>>> supply. Saves me from rolling my own with an opamp and a mosfet. >> >>>> >> >>>> It's an ST1L08. >> >>>> >> >>>> So why is the data sheet file en.DM00123507.pdf ? >> >>> >> >>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >> >> >> >> Lying? It's all over the data sheet. It's how they get the millivolts >> >> of dropout. I do that when I make my own super-LDOs, power an opamp >> >> from some higher voltage and over-drive an nfet follower down to >> >> milliohms of Rds-on. >> >> >> >>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >> >>> >> >> >> >> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >> >> would be 0.24 watts dissipated. Actually, I don't need that much >> >> current to run a couple DRAM chips. >> >> >> > >> >Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >> >series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >> >drop-out. 16 different fixed output voltages from 2.1V to 12V >> >with 3% tolerance. As usual with products originating in the >> >East, the datasheet is rather sparse about details, but I've used >> >them and they do what I want. >> >> Is it stable with low ESR caps? We use polymers or ceramics mostly. >> >> We need so many goofy voltages that we usually buy adjustable >> regulators for stock. The board that I'm doing now has a 24-channel >> analog mux to BIST the power supplies, using the dreadful Xilinx >> 1-volt XADC that's inside their FPGAs. Free and worth it. >> >> > >> >> You sure are in a bad mood lately. >> >> >> >I've noticed that lately with some regulars here, including a few >> >who normally exhibit decent manners. >> >> Well, some never show any sign of manners. They are repulsive but >> you've got to feel sorry for them, stuck being around themselves all >> day. >> >> There's a basically perfect -1 correlation between being obnoxious and >> designing electronics. > >Seriously! Rigging up your little pseudo-LDO is not "designing" electronics. That's like saying figuring the part number suffix for the fixed 1.5V output is "designing" electronics.Rolling your own opamp-nfet LDO is not designing electronics? The loop could oscillate; transient load-step response matters; the fet could oscillate; the fet could fry; the loop dynamics changes radically at low dropout voltages, when the fet becomes ohmic; loads could have different C and ESR and stuff. This takes design. You seem to think that all electronic design is trivial. Well, whatever it is, I enjoy it. You should find something to enjoy. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●May 19, 20202020-05-19
On Tuesday, May 19, 2020 at 12:26:28 PM UTC-4, jla...@highlandsniptechnology.com wrote:> On Tue, 19 May 2020 08:04:52 -0700 (PDT), > bloggs.fredbloggs.fred@gmail.com wrote: > > >On Tuesday, May 19, 2020 at 9:50:43 AM UTC-4, jla...@highlandsniptechnology.com wrote: > >> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > >> > >> >On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >> >> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >> >> bloggs.fredbloggs.fred@gmail.com wrote: > >> >> > >> >>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >> >>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >> >>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >> >>>> > >> >>>> It's an ST1L08. > >> >>>> > >> >>>> So why is the data sheet file en.DM00123507.pdf ? > >> >>> > >> >>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >> >> > >> >> Lying? It's all over the data sheet. It's how they get the millivolts > >> >> of dropout. I do that when I make my own super-LDOs, power an opamp > >> >> from some higher voltage and over-drive an nfet follower down to > >> >> milliohms of Rds-on. > >> >> > >> >>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >> >>> > >> >> > >> >> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >> >> would be 0.24 watts dissipated. Actually, I don't need that much > >> >> current to run a couple DRAM chips. > >> >> > >> > > >> >Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >> >series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >> >drop-out. 16 different fixed output voltages from 2.1V to 12V > >> >with 3% tolerance. As usual with products originating in the > >> >East, the datasheet is rather sparse about details, but I've used > >> >them and they do what I want. > >> > >> Is it stable with low ESR caps? We use polymers or ceramics mostly. > >> > >> We need so many goofy voltages that we usually buy adjustable > >> regulators for stock. The board that I'm doing now has a 24-channel > >> analog mux to BIST the power supplies, using the dreadful Xilinx > >> 1-volt XADC that's inside their FPGAs. Free and worth it. > >> > >> > > >> >> You sure are in a bad mood lately. > >> >> > >> >I've noticed that lately with some regulars here, including a few > >> >who normally exhibit decent manners. > >> > >> Well, some never show any sign of manners. They are repulsive but > >> you've got to feel sorry for them, stuck being around themselves all > >> day. > >> > >> There's a basically perfect -1 correlation between being obnoxious and > >> designing electronics. > > > >Seriously! Rigging up your little pseudo-LDO is not "designing" electronics. That's like saying figuring the part number suffix for the fixed 1.5V output is "designing" electronics. > > Rolling your own opamp-nfet LDO is not designing electronics?Of course it is, but you're not doing that.> > The loop could oscillate; transient load-step response matters; the > fet could oscillate; the fet could fry; the loop dynamics changes > radically at low dropout voltages, when the fet becomes ohmic; loads > could have different C and ESR and stuff. This takes design.It would be foolish getting distracted by that minutia when you have a much bigger task to complete. Take the non-design off the shelf LDO approach.> > You seem to think that all electronic design is trivial. Well, > whatever it is, I enjoy it. You should find something to enjoy.If the engineering is non-trivial, it will probably end up being problematic. The best products are trivialized engineering.> > > > -- > > John Larkin Highland Technology, Inc > > Science teaches us to doubt. > > Claude Bernard
Reply by ●May 19, 20202020-05-19
On Tuesday, May 19, 2020 at 12:26:28 PM UTC-4, jla...@highlandsniptechnology.com wrote:> On Tue, 19 May 2020 08:04:52 -0700 (PDT), > bloggs.fredbloggs.fred@gmail.com wrote: > > >On Tuesday, May 19, 2020 at 9:50:43 AM UTC-4, jla...@highlandsniptechnology.com wrote: > >> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > >> > >> >On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >> >> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >> >> bloggs.fredbloggs.fred@gmail.com wrote: > >> >> > >> >>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >> >>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >> >>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >> >>>> > >> >>>> It's an ST1L08. > >> >>>> > >> >>>> So why is the data sheet file en.DM00123507.pdf ? > >> >>> > >> >>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >> >> > >> >> Lying? It's all over the data sheet. It's how they get the millivolts > >> >> of dropout. I do that when I make my own super-LDOs, power an opamp > >> >> from some higher voltage and over-drive an nfet follower down to > >> >> milliohms of Rds-on. > >> >> > >> >>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >> >>> > >> >> > >> >> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >> >> would be 0.24 watts dissipated. Actually, I don't need that much > >> >> current to run a couple DRAM chips. > >> >> > >> > > >> >Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >> >series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >> >drop-out. 16 different fixed output voltages from 2.1V to 12V > >> >with 3% tolerance. As usual with products originating in the > >> >East, the datasheet is rather sparse about details, but I've used > >> >them and they do what I want. > >> > >> Is it stable with low ESR caps? We use polymers or ceramics mostly. > >> > >> We need so many goofy voltages that we usually buy adjustable > >> regulators for stock. The board that I'm doing now has a 24-channel > >> analog mux to BIST the power supplies, using the dreadful Xilinx > >> 1-volt XADC that's inside their FPGAs. Free and worth it. > >> > >> > > >> >> You sure are in a bad mood lately. > >> >> > >> >I've noticed that lately with some regulars here, including a few > >> >who normally exhibit decent manners. > >> > >> Well, some never show any sign of manners. They are repulsive but > >> you've got to feel sorry for them, stuck being around themselves all > >> day. > >> > >> There's a basically perfect -1 correlation between being obnoxious and > >> designing electronics. > > > >Seriously! Rigging up your little pseudo-LDO is not "designing" electronics. That's like saying figuring the part number suffix for the fixed 1.5V output is "designing" electronics. > > Rolling your own opamp-nfet LDO is not designing electronics? > > The loop could oscillate; transient load-step response matters; the > fet could oscillate; the fet could fry; the loop dynamics changes > radically at low dropout voltages, when the fet becomes ohmic; loads > could have different C and ESR and stuff. This takes design.Yes, a feedback circuit can be unstable. You have told us your method of finding and fixing such issues is iteration through simulation and then on the test bench rather than applying math which will give you the right answer the first time.> You seem to think that all electronic design is trivial. Well, > whatever it is, I enjoy it. You should find something to enjoy.So does applying iteration make you a designer or a tinkerer? Iteration is the method most amateurs use. I'm presently working on a board for a ventilator. The engineering isn't so hard other than trying to get the simulation models working. LTspice can be a real chore when a model isn't available off the shelf. There is so little documentation available on the digital parts that the only way to assure the behavior is to test the model thoroughly before using it in your circuit. I found that the DFLOP model has undocumented and unexpected behavior when both SET and CLEAR inputs are asserted simultaneously. No one in the LTspice group knew about this. Rather than even address it seriously they indicated I should not expect any particular behavior, the parts work as the designer intended. I wasn't complaining about the behavior as much as I was complaining that it was not just unexpected, but undocumented. Many times LTspice is a sucky tool to use especially if you need to use the Help. -- Rick C. -+ Get 1,000 miles of free Supercharging -+ Tesla referral code - https://ts.la/richard11209
Reply by ●May 19, 20202020-05-19
On Tue, 19 May 2020 15:02:32 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com wrote:>On Tuesday, May 19, 2020 at 12:26:28 PM UTC-4, jla...@highlandsniptechnology.com wrote: >> On Tue, 19 May 2020 08:04:52 -0700 (PDT), >> bloggs.fredbloggs.fred@gmail.com wrote: >> >> >On Tuesday, May 19, 2020 at 9:50:43 AM UTC-4, jla...@highlandsniptechnology.com wrote: >> >> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >> >> >> >> >On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >> >> >> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >> >> >> bloggs.fredbloggs.fred@gmail.com wrote: >> >> >> >> >> >>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >> >> >>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >> >> >>>> supply. Saves me from rolling my own with an opamp and a mosfet. >> >> >>>> >> >> >>>> It's an ST1L08. >> >> >>>> >> >> >>>> So why is the data sheet file en.DM00123507.pdf ? >> >> >>> >> >> >>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >> >> >> >> >> >> Lying? It's all over the data sheet. It's how they get the millivolts >> >> >> of dropout. I do that when I make my own super-LDOs, power an opamp >> >> >> from some higher voltage and over-drive an nfet follower down to >> >> >> milliohms of Rds-on. >> >> >> >> >> >>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >> >> >>> >> >> >> >> >> >> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >> >> >> would be 0.24 watts dissipated. Actually, I don't need that much >> >> >> current to run a couple DRAM chips. >> >> >> >> >> > >> >> >Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >> >> >series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >> >> >drop-out. 16 different fixed output voltages from 2.1V to 12V >> >> >with 3% tolerance. As usual with products originating in the >> >> >East, the datasheet is rather sparse about details, but I've used >> >> >them and they do what I want. >> >> >> >> Is it stable with low ESR caps? We use polymers or ceramics mostly. >> >> >> >> We need so many goofy voltages that we usually buy adjustable >> >> regulators for stock. The board that I'm doing now has a 24-channel >> >> analog mux to BIST the power supplies, using the dreadful Xilinx >> >> 1-volt XADC that's inside their FPGAs. Free and worth it. >> >> >> >> > >> >> >> You sure are in a bad mood lately. >> >> >> >> >> >I've noticed that lately with some regulars here, including a few >> >> >who normally exhibit decent manners. >> >> >> >> Well, some never show any sign of manners. They are repulsive but >> >> you've got to feel sorry for them, stuck being around themselves all >> >> day. >> >> >> >> There's a basically perfect -1 correlation between being obnoxious and >> >> designing electronics. >> > >> >Seriously! Rigging up your little pseudo-LDO is not "designing" electronics. That's like saying figuring the part number suffix for the fixed 1.5V output is "designing" electronics. >> >> Rolling your own opamp-nfet LDO is not designing electronics? > >Of course it is, but you're not doing that.Do I have to give the money back?> >> >> The loop could oscillate; transient load-step response matters; the >> fet could oscillate; the fet could fry; the loop dynamics changes >> radically at low dropout voltages, when the fet becomes ohmic; loads >> could have different C and ESR and stuff. This takes design. > >It would be foolish getting distracted by that minutia when you have a much bigger task to complete. Take the non-design off the shelf LDO approach.But electronic design is minutia, especially when you want your boards to work first try.> >> >> You seem to think that all electronic design is trivial. Well, >> whatever it is, I enjoy it. You should find something to enjoy. > >If the engineering is non-trivial, it will probably end up being problematic. The best products are trivialized engineering.Show us some. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●May 19, 20202020-05-19
