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LM2576HV: MAX INPUT VOLTAGE and max output current for LM2576HV-12

May 24, 2019, 12:18 am
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Part Number:LM2576HV

Dear Forum

I am trying to use the LM2576HV-12 in my design which requires a step down from 53v  to 12v.

I am struggling a bit to see how this chip will do the job considering the max input V for a given output current.

I cannot see (from the attached graph) that I can get even 1 amp from the circuit  if I have 53volts Vin.

Can someone help me 'get' this graph and tell me if I am on the right track to expect a  1 amp @12 output when I have 53v input?

Does the shading mean the circuit would be out of SOA if run with a higher DC input voltage for that current output?

As I look at this graph, it seems to be saying:

Max Vin for 12v 1amp out= 20v 


cheers

Julian

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UC2825: Equation for output frequency

May 24, 2019, 12:27 am
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Part Number:UC2825

I think that equation of UC2825's output frequency is below;

fo = ?? / (Rt*Ct)

Please let me know about UC2825's factor of "??".

(For example, UC1845's factor is 1.72)

【Background】

Customer want to set just fo: 100kHz (f_osc: 200kHz), but not fit exactly. 

⇒Rt: 3300Ω and Ct:2200pF, result was fo: 110kHz

By the way, is UC2825 frequency tolerance tend to upper side?

Best regards,

Satoshi

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To Apple IPAD charge, it can't get 2.1A charge current.

May 24, 2019, 12:30 am
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Part Number:TPS2546

Hi

 We use TPS2546 for a USB Charging Port Controller, and we set 0111 for the DCP-AUTO mode. When the load is the Apple IPAD, it can't ouput 2.1A and it only can get 1.8A. Can you check what limit the charge current ?　thanks

 (Please visit the site to view this file)

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Asking for the recommendation to replace OVP switch

May 24, 2019, 12:59 am
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TLV62565: Power save mode

May 24, 2019, 1:01 am
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Part Number:TLV62565

Hello

            We use TLV62565 (3.3Vin, 1.2Vout, 0.6A) and use electric load meter and power supply to input 3.3V. We find TLV62565 looks not enter power save mode. Could I know what is the issue root cause for it? Thank you. 

BR

Patrick

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Asking for the recommendation LED driver solution

May 24, 2019, 1:04 am
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Hi Team,

Customer is looking LED driver 6S2P(15mA )solution to replace PAM2841.

 

Would you please recommend the proper solution for this?

 

Here is customer request:

Vin: 3V~5V

Vout: 6S2P white LED (LED voltage = 3V)

Iout 20mAmax

 

 

 

 

BR,

SHH

 

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LMR36015: Asking for the LMR36015 peak an abnormal issue

May 24, 2019, 1:18 am
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Part Number:LMR36015

Hi Team,

Customer is using LMR36015 as 5V system power.


Please kindly help for cusotmer's four question here.
1. the system load varies widely as WIFI and image sensor function, load current(max load condition) measured result as below:
system overall load is not high, but peak current is high;



2. In datasheet, it shows that LMR36015's limit current is 1.5A. This limit current is peak current or continues current?

3. customer found the design will lose 5V output sometimes. Does this have anything to do with system load(max load condition)?

4. Do you have any comments that the design can improve the current varies at LM36015 side?


BR,
SHH

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BQ76940: is there have any example code of controlling the BQ76940?

May 24, 2019, 1:46 am
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Part Number:BQ76940

HI

1. I saw the TIDA-00792 in TI Design, is there any source code of the Host side, by any platform is welcom(MSP430, TM4C, Hercules,C2000....)

2. does TI has the example code of using the MCU to paly the role as Gauge IC? We want to use the MCU to calculate the SoC / SoH from battery without the gauge IC 

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TPS61220: output voltage & off mode

May 24, 2019, 1:47 am
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Part Number:TPS61220

Dear Sir, good morning

I use a battery 1.7... 2.4 V at the TPS61220's input. I set 3.8 V output voltage.

I do not like the fact, that when it is turned off (EN = 0) there is voltage at the output. Please, report, is there a similar chip, where in the OFF state, there is 0V at the output? Or close to 0V. 

TIA

Sincerely,

Vladimir Naumenkov

www.agat.by

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BQ25890: BQ25890 – there has unknowns pulse after charging finish

May 24, 2019, 2:19 am
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Part Number:BQ25890

Please refer below charging profile. We find there has two unknowns pulse after charging finish. The one is current profile, another one voltage profile. We also can see the pulse in the voltage. May I know why they have these two pulse? Thanks.

BR,

Gary

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BQ34110: End-of-service : Cell Resistance Calculation + Direct Resistance Decisioning

May 24, 2019, 2:20 am
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Part Number:BQ34110

Hello,

For our UPS application we'd like to estimate the end of service of our battery using the method provided by the bq34110.

One of our difficulties is for the cell resistance calculation. In the technical reference document, it says that we need to calculate initial RCELL values ("The Rcell High & Low Temperature Coefficients are obtained during a pre-production test whereby the customer initiates Initial Rcell calculations at temperatures of 5°C, 25°C, and 40°C", 2.11.1.6 Cell Resistance Calculation). The problem is that our battery may not be fixed (choosen by our client). Actually we know that the battery with be a Valve Regulated Lead Acid Battery 12V with float voltage=13.65 @20°C, but the capacity and the manufacturer could be different from our test battery that we would use to obtain the RCELL values. Do you think that we could consider these values as independant of the capacity and the manufacturer or these should fit perfectly the battery in use ?

Our second concern is with the threshold decision (2.11.1.7.1 Direct Resistance Decisioning). We would like to say our battery is no more "good" when the capacity is no more high enough. Is there a way to link the cell resistance with the battery capacity. So when the Rcell goes below the threshold we would say the capacity is below the acceptable capacity threshold and our battery should be replaced.

Thanks and regards,

Axel

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TPS62136: In Constant current regulation - woult it stable with

May 24, 2019, 2:23 am
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Part Number:TPS62136

Hello

Proj. description: to design resistive  switching wire heater psu with regulated current. The load resistance is extremely low

Load resistance from 0.5 ohm

- Current regulated from 0.2 to 4.0 Amp

- Max output volatge at least 5V.

- Least possible Voltage ripple

- Maximum effciency for least heat dissipation (will work in sealed/closed/isolated env.)

output voltage requirement is to swing to ner 0V asthis wire heater would need about 0.1V output to feed 200mA in to 0.5ohm.

There is a pair questions:

1. what is the difrence  between TPS62136 and TPS62135.

2. would the TPS62136 be stable with added V to I conversion on INA250 and OPA348?   specified INA250A2 BW ~50kHz and OPA348 ~1Mhz.

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TPS65084: Similar TPS65084 automotive part suggestion

May 24, 2019, 2:27 am
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Part Number:TPS65084

Hi Team,

Customer want to check if have similar TPS650864 automotive PMIC could suggest ?

Voltage input  is 12V

Voltage output as below list

  1. 1.     Buck1 : 5V/3A
  2. 2.     Buck2: 0.85V/7A
  3. 3.     Buck3: 1.1V/1A
  4. 4.     Buck4: 3.3V/1A
  5. 5.     Buck5: 1.25V/1A
  6. 6.     Buck6: 1.8V/1A
  7. 7.     VTT LDO: 0.9V300mA
  8. 8.     LDO1: 1.8V/50mA
  9. 9.     LDO2: 1.8V/500mA
  10. 10.  LDO3: 1.2V/100mA

The Xilinx FPGA is used XAZU2EG-1SBVA484Q.

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LM137: lm137 power dissipation

May 24, 2019, 2:35 am
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Part Number:LM137

Hello,

I would like to check something please:

If the input to the LM137 is -7V, the output -5V and the load current 1A, will the device's power consumption be ~ ¦(-7 - -5)*1¦ = 2W?

thank you

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TPS22919: Look for lower Vih min threshold than TPS22919

May 24, 2019, 2:58 am
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Part Number:TPS22919

Hello professional,

My customer look for load switch that has lower VIH min than TPS22919.

I tried to find appropriate device for this requirement. However  I only could found the device which VIH min is 1V.

Do you have any candidates for this requirement?

Thank you,

Kuramochi

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TPS23753A: The output power of 6 boards is basically guaranteed to be 13W, but there are 2 boards, and the output power of no.3 and no.6 is only about 12.5w.What causes this problem? Please help to solve it.

May 24, 2019, 3:15 am
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TPS40322: Hiccup Time

May 24, 2019, 3:54 am
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Part Number:TPS40322

Hi E2E,

The datasheet describe as below:


Soft-star Cap CSS is 39nF, SS time = 2.34ms
the 6 SS cycles is 14ms.

Why my hiccup time reach up to 31ms?

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UCC21530: UCC21530 output creepage distance for 1200VDC DC-link voltage

May 24, 2019, 3:59 am
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Part Number:UCC21530

Hello,

we would like to use UCC21530 driver for a three-phase application with DC-link voltage up to 1200VDC. The application is a mains connected supply.

According to EN 62477-1, for 1200Vdc we would need around 4.2mm for creepage distance not only in our PWB but also in UCC21530 package (CTI >600 - I). These 4.2mm is with some type of coating which allow us to download the pollution degree from 2 to 1. But even with this coating, we can't reach 4.2mm with the distance of 3.3mm between pins 11 and 14 of UCC21530.

 We see in the datasheet that this driver is suitable for 1850Vdc but we can't see how to ensure creepage distances. What is your proposal to solve this issue?

Thank you very much

Maite

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TPS2546: How to implement 2.5A output current

May 24, 2019, 4:13 am
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Part Number:TPS2546

Hello

From Table 1 shows these Operating modes maximum current just 1.5A ,so how can I set to implement up to 2.5A output ? thanks

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TPS43061: GaN-transistors driving

May 24, 2019, 4:59 am
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