Linear Regulators

Forum Post: RE: LP2954IMX SENSE and 5V TAP pins

Michael Long1 — Thu, 23 May 2013 21:42:00 GMT

Excellent. Thank you for the quick replies.

Forum Post: RE: TPS79333 Output shorted to Input

Kartik Sinha — Thu, 23 May 2013 21:28:00 GMT

Oscar,

At this point I will advise you to please submit the failed units for Failure Analysis. Please fill up the attached form and ship according to instructions mentioned in the attachment as well. It will further help the FA team if you can mention the following in the form itself:

Detailed information about the failure. What’s specifically is failing with the device? Low output voltage? Device not enabling correctly? Please be specific.
What is the failure rate that the customer is seeing? How many devices are failing out of how many used in production?
Can any tracking information be provided about the failures? Ship Trace Codes (STC), Lot trace codes (LTC), Assembly lot #s, etc.? Can the customer provide a picture of the reel label(s) that they are seeing failures from?
Provide the operating conditions of the failure (temperature, pin biasing conditions, etc.)
Can an application schematic be provided? This will help the Verification team in Dallas duplicate the customer set-up conditions on the bench.
Does the customer have any waveform captures of the failure?

(Please visit the site to view this file)

Some last thoughts I had:

In the failed units do you see any physical damage?
What is the reason for the pull ups? You can email me the LDO portion of the schematic at k-sinha@ti.com if you like.

Forum Post: RE: TPS7A4001 / direct connected Power Pad and GND ?

Kartik Sinha — Thu, 23 May 2013 18:46:00 GMT

Ryuji-san,

I have verified, the GND pin is internally directly connected to the PowerPAD.

Regards,

Kartik

Forum Post: RE: TPS7A4001 / Open, Short test of each pins

Kartik Sinha — Thu, 23 May 2013 17:28:00 GMT

Ryuji-san,

Sorry for my earlier post, I had thought you are asking about the TPS7A4701.

For TPS7A4001 are you trying to find out which pins have ESD diodes connected to them? Or are you trying to see maximum leakage for each pin? Thanks

Regards,

Kartik

Forum Post: RE: ψJT for legacy products

S.Satoshi — Thu, 23 May 2013 17:08:00 GMT

Hi Donald Jones-san,

Thank you for information of LP38502ATJ-ADJ !!

I'm also waiting for the information for remaining devices.

Best Regards,

Sonoki

Forum Post: RE: About LM78L05

greenja — Thu, 23 May 2013 07:33:00 GMT

Hello Masa,

Those numbers refer to package options for tape & reel. Depending on your method of pick & place, you can select a different part orientation. You can find the details in the following package data sheet.

http://focus.ti.com/en/download/qlty/MS101205.pdf

Thanks,

Forum Post: RE: LM340 thermal resistance

Donald Jones — Wed, 22 May 2013 16:33:00 GMT

Results are back from the thermal modeling group for the LM340MP ...

Theta JA- (High K) = 60.2 °C/W
Theta JC, top = 42.1 °C/W
Theta JB = 8.9 °C/W
Psi JT = 2.7 °C/W
Psi JB = 8.8 °C/W

Forum Post: RE: TPS7A470x / 1kV ESD, HBM version RTM

Kartik Sinha — Wed, 22 May 2013 16:26:00 GMT

Ryuji-san,

We will know for sure by end of Q2, thanks.

Regards,

Kartik

Forum Post: RE: TPS7A49 / TPS7A30 resistive divider current

Alexander Uvarov — Wed, 22 May 2013 02:26:00 GMT

Yes, Kartik, it helps.

Thanks a lot for your reply! The question is solved.

Regards,

Alexander.

Forum Post: RE: TPS76901-HT Vref value and tolerance

john michalik99980 — Tue, 21 May 2013 12:47:00 GMT

Kartik,

Thanks for the research.

Again checking the data sheet I find the Vout variation due to temperature is -5% to +3% over the temperature range of -55C to 125C. Also Figure 1 Vout vs Temperature documents the falloff of the output voltage with temperature agreeing with the data sheet.

However, I will keep a watch on the Vref value with any data sheet release since I noticed from revision B to C it changed from 1.127 volts to 1.160 volts. This will affect the values of the programming resistors.

Thanks again for your help.

John

Forum Post: RE: LDO for weighing scale for high precision applications

Kartik Sinha — Mon, 20 May 2013 23:53:00 GMT

Sushma,

Please also take a look at the TPS7A35. This is in preview right now will be released by Q4 2013.

Regards,

Kartik

Forum Post: RE: TPS72301 / About EN at the time of a negative voltage input.

Kartik Sinha — Mon, 20 May 2013 23:33:00 GMT

Yusuke-san,

Output will be not 0V once Enable pin voltage is > 1.5V or < -1.5V

Please let me know if you have any more questions.

Regards,

Kartik

Forum Post: RE: Linear regulators

ed meeks — Sat, 18 May 2013 01:20:00 GMT

The voltage source is a small PSD5-36 type transformer 36VCT @ .35A and I'll wire it series with centertap to have two 18V outputs going to the regulators. I'll need 15V going to the crossovers.In the attach schematic D1-D8 are 1N4937 diodes, C1 and C2 are the 1000uF caps, IC1 and IC2 are the regulators, C3 and C4 are the 10uF caps, R1 and R2 are 1k resistors. D5 and D6 are LEDs to indicate the 15V is on and active.V++ and GND and V- go to the crossovers.

Forum Post: RE: LP2950ACZ3.3 not working?

Donald Jones — Fri, 17 May 2013 17:38:00 GMT

LP2950ACZ-3.3 Adjustable Micropower Voltage Regulators in TO-92 package.

LP2950ACZ-3.3 should work well for 5.0V to 3.3V conversion up to the rated 100mA current.

" ... The part is connected to 4.95 volts (3) and ouputs 1.76 V (on 1) ... "

No idea. Either the part is damaged, or there is some undiscovered connection error.

Yes, TI now owns all the assets of the former National Semiconductor. Yes, TI has a version of LP2950 with a different orderable number.

To date, there have been no changes to the National version. The Fab site is still the same, the assembly site is still the same, the final test is still the same, the QA procedures are still the same.

Forum Post: RE: About TPS7A7001 soft start

Kartik Sinha — Fri, 17 May 2013 01:25:00 GMT

Hello,

The TPS7A7001 does not have a Soft Start function. Thanks

Regards,

Kartik

Forum Post: RE: TPS73133DBVR Failure

Kartik Sinha — Thu, 16 May 2013 23:50:00 GMT

Hi Andrew,

Please fill up the attached form and mention the following information in the 'description' section:

Detailed information about the failure. What’s specifically is failing with the device? Low output voltage? Device not enabling correctly? Please be specific.
What is the failure rate that the customer is seeing? How many devices are failing out of how many used in production?
Can any tracking information be provided about the failures? Ship Trace Codes (STC), Lot trace codes (LTC), Assembly lot #s, etc.? Can the customer provide a picture of the reel label(s) that they are seeing failures from?
Provide the operating conditions of the failure (temperature, pin biasing conditions, etc.)
Can an application schematic be provided? This will help the Verification team in Dallas duplicate the customer set-up conditions on the bench.
Does the customer have any waveform captures of the failure?

The shipping instructions and address are provided in the attachement as well. Thanks

Regards,

Kartik

(Please visit the site to view this file)

Forum Post: RE: LM338T Adjustable Regulator

Donald Jones — Thu, 16 May 2013 18:59:00 GMT

LM338T 5A Adjustable Regulator in TO-220 package

" ... my devices get hot under load ... "

Yes, totally expected. Linears regulators are inefficient when there is large input to output voltage difference along with high(er) load currents.

The power dissipated as heat inside the package is generally determined by:

Pdiss = ((Vin - Vout) x Iout)

where Pdiss is the dissipation in W, Vin and Vout are the input and output voltages in V, and Iout is the load current in A.

If Vout and Iout are constant, then changing the Vin will directly change the heat (W) that needs to be dissipated from the device.

You did not give your Vout or Iout conditions so I am not able to do the math examples here.

There is no ~correction~, it is what it is. Thermal management. (i.e. heat-sink, fan, etc.) is called for.

An SMPS could be a better solution as the efficiency is much higher (typically > 80%). Yes, a bit more complex, but quite possibly can totally eliminate the need for large heat-sink, fans, etc.

Forum Post: RE: TPS7A4701RGWT

Kartik Sinha — Wed, 15 May 2013 17:08:00 GMT

Hello,

The TPS7A4701 should be available by the beginning of Q4 2013. Please check back in July for an updated schedule. Thank you

Regards,

Kartik

Forum Post: RE: Could you recommend a solution of negative output LDO?

Kartik Sinha — Wed, 15 May 2013 17:06:00 GMT

Hi,

I am sorry but TI currently does not offer such an LDO. You could try using a power inverting amplifier to get -0.9V

Regards,

Kartik

Forum Post: RE: need power supply solution

Kartik Sinha — Wed, 15 May 2013 01:17:00 GMT

Hello Vishal,

Thank you for your post. In order to design your power supply, I suggest you take a look at TI's WEBENCH tool first. Please visit the link below:

http://webench.ti.com/webench5/power/webench5.cgi?app=powerarchitect&lang_chosen=en_US

Hope this helps.

Regards,

Kartik