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LM5035: LM5035: Burn out the secondary Mos tube and the starter when no-load current limit starts at 0.1A？

September 10, 2019, 7:27 pm
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Part Number: LM5035

Hello，

I use the LM5035 as a power supply, modeled after the typical application of the LM5035's 48V to 5V, the circuit principle is basically the same.The circuit block diagram is as follows:


The problem currently encountered is that the no-load current limit starts at 0.1A, which will burn out the secondary Mos tube and the starter. At present, there are no ideas for troubleshooting.Could you give me some suggestions about focus on which areas to check and provide corresponding troubleshooting methods and steps?

Looking forward to your reply!

Thank you!

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Compiler/TLV707: Is there fixed 5V output for TLV707?

September 10, 2019, 7:30 pm
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Part Number: TLV707

Tool/software: TI C/C++ Compiler

Hi , 

I saw page 1 of TLV707 datasheet said that TLV707 could support fixed-output voltage up to 5V and I also saw 5V load regulation waveform at figure 3. But I could not find 5V output version at package information (P28-P31) of datasheet. Could you please let me know if TLV707 have 5Vout fixed version? Thank you.

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TPS5430: Phase Node Negative Voltage Question

September 10, 2019, 7:46 pm
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BQ76930: BQ76930 DIE Power consumption

September 10, 2019, 8:23 pm
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Part Number: BQ76930

BQ76930 have two die and the lower die power consumption is more than upper die, what is the mainly cause the different, is the alert pin power consumption or communication power consumption?

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TPS548A20: Schematic Review for 12V to 3.3V 10A

September 10, 2019, 8:36 pm
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Part Number: TPS548A20

Hi TI expert,

Could you help to review the schematic with TPS548A20? Do we need to consider to add heatsink since we need to support 70°C?

Vin: 12V (11V~12.9V)

Vout: 3.3V

Iout: 10A max (5A for the thermal and power loss consideration)

Operational Ambient: -10°C to 70°C

PCB layers: 10 layers. 

Some questions:

1. Do we need to consider to add heatsink since we need to support 70°C? The webench simulation result seems too good on efficiency, comparing a test result with 12V to 1V 15A 500Khz. 

2. Do we need to do bode plot test for such DCAP3 control? Will our design be stable? Per the datasheet, the LC pole and a zero are mentioned. But no much idea how to calculate the phase margin and cross-over frequency with the selected components.

Thanks,

Dora

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TLC5941: Output current variation among channels and devices

September 10, 2019, 8:38 pm
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Part Number: TLC5941

Hi team,

My customer wants to clarify max output current variation of TLC5941 including errors introduced by load and line regulations.

1. Do you have any data for the max output current variation?
I'm asking this questions because IO(LC) looks that it doesn't include errors introduced by load and line regulations.

2. As one quick confirmation. "Device to Device" and "channel to channel" variation are involved in IO(LC), right?

3. If you don't have the data, Can we estimate the max value by following equation?

Max error range(480ohm) = (ΔIO(LC)^2+ΔIO(LC3)^2+ΔIO(LC3)^2)^(1/2) = (13.12^2+6^2+8^2)^(1/2) = 16.5%


Here is my understanding of each parameter in the datasheet

IO(LC) : Estimated output current range under VO = 1 V, R(IREF) = 640 Ω(Vo and IREF dependency are not included)

ΔIO(LC0) : Channel to Channel output current error

ΔIO(LC1) : Device to Device output current error @ 20mA

ΔIO(LC2) : Device to Device output current error @ 80mA

ΔIO(LC3) : Output current error depending on VCC

ΔIO(LC3) : Output current error depending on VO

Regards,

Takashi Onawa

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TPS2121: TPS2121 output drop when switching

September 10, 2019, 8:39 pm
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Part Number: TPS2121

I have two input，all is 5V.

IN1:5V_DC

IN2:5V_USB

When 5V_DC pulls out and 5V_USB keeps，the output volotage will drop 

And I Test the ST pin,but this pin still low volotage,didn't change

I also find that the output volotage will be 4.2V in IN1,when resistor load is 5R.

Is there something wrong with the output volotage?

Could you tell me the reason？ (Please visit the site to view this file)

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BQ24266: External NTC Monitoring Review Request

September 10, 2019, 8:44 pm
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Part Number: BQ24266

Hello,

Could you please review my customer design? He says CHG does not disable when Vhot<1.4V (Vdrv * 0.3).

He connects LED to /CHG pin to check that.

<Parts used>

THermistor

0℃：Rcold＝27.22kΩ／60℃：Rhot＝3.01 kΩ

<Designed value>

RLO：13kΩ　／　RHI：5.9 kΩ

<Test procedure>

Heating thermistor with a hair dryer, and then observe the TS pin.

Heat until TS pin voltage goes below Vhot = 1.4V.

When charging stopped, /CHG LED is supposed to turn off.

Please feel free to correct me if I'm wrong. Thank you.

Regards,

Itoh

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TPS61185: ISET switching issue

September 10, 2019, 8:49 pm
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Part Number: TPS61185

Hello

     Customer use below schematics to do ISET switching testing. But if switching rate is too fast, it will cause partial backlight LED not light up. 

     Could we know what is the issue root cause?  Has any timing relationship between ISET switching and PWM ? Thank you.    

BR

Patrick

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LM1084: LM1084 5.0 fixed voltage output is not fixed

September 10, 2019, 9:05 pm
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Part Number: LM1084

Hello,

 I am using LM1084 5.0 fixed voltage regulator . I given input ranging from 5V to 15 V , my output was supposed to be fixed at 5V but I observed that it is varying linearly with the input volate.

 I have grounded pin 1, put 10uf electrolytic capacitor across input and 100uf electrolytic capacitor across output.

 Can anyone help me out here?

Thanks 

Ashish 

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UCC2897A: switching frequency

September 10, 2019, 9:33 pm
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Part Number: UCC2897A

Hi

I use UCC2897A to design active clamp forward input 36~72V output 12V/10A.

But I found a problem about switching frequency.

I'd like it operation at 180kHz  but it only appears at no load or below 20W output.

When the output load increases over 20W,the switching frequency changes to 195kHz.

What it might be the root cause?

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Gate Driver IC for 2 Switch forward Converter.

September 10, 2019, 10:14 pm
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Hi all, 

I will start working on design and development of Power supply, with continuous output power of 350W  and peak power of 550W.  ((universal input ) 

I intend to use 2 switch forward converter with Front End PFC. 

It would be an TL431 based feedback with controller Sitting on Primary side. 

Auxiliary Power supply, will be a non isolated 15V output to power up controller.  

Does Ti Recommend any Gate Driver for 2 S/W Forward converter, i do not wish to use Pulse Transformer and rest of gate driver circuit. 

Thanks 

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TPS61158: TPS61158 Open Load Issue

September 10, 2019, 10:22 pm
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Part Number: TPS61158

Dear TI Team,

The TPS61158 is designed and in use.
VCC: 5V
Vout: 18V
LED Load: 10mA

In the process of producing and testing the board, Anode / Gnd is measured by the tester with no load on the output and tested.
However, the chip dead with the OVP symptom without load.

After changing the test environment and loading the output, I confirmed that it operates normally in the same environment.
I want to check if the TPS61158 product can have a problem when it is open load.
Attach schematics and measurement waveforms.

CTRL Waveform

Output Load Waveform


 

Output Open Load Waveform


I would like to know why Chip dead.

Thanks.

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WEBENCH® Tools/UCC28C42: UCC28C42 PWM IC Issues

September 10, 2019, 10:25 pm
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Part Number: UCC28C42

Tool/software: WEBENCH® Design Tools

Hi, 

I am working with DC-DC converter for Auxiliary power supply application .

Power supply input and output details are below,

Input voltage : 24 V to 164Vdc

Output voltage :24 Vdc

Output power : 48W

Converter Topology: Fly back

Isolation : Yes

Transformer core : EE25, N87 Material from EPCOS

Converter switching Frequency : 100KHZ  

Target Efficiency :>90% 

In this power supply ,UCC28C42 IC is used to generate the PWM pulse to drive the Mosfet .During board bring up without population transformer ,we fed external 15V supply to UCC28C42 IC VCC pin 

and IC can able to generate the PWM Pulse with duty cycle of 95% .If we populate the transformer in board and feed the input voltage of 28V to input connector ,as soon as turn on the power supply input,PWM ic not able to generate PWM pulse and IC Vcc pin & ground pin got shorted.However,this topology and circuit simulated and recommended by TI's WEBENCH Tool.

Could you please look at the issues and give your suggestion to rectify the issues.

Please find the attached schematic for your reference.

Regards,

Sendhil kumar

        

      

 

  

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Isolated DC DC converter part suggestion

September 10, 2019, 10:38 pm
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Hi,

Need to pick a suitable part for Isolated DC-DC converter application as per following specs.

Below are the 2 variants:

1) Vinput 60V~90 VDC, Output 13.5V, Wattage 500~600W

2) Vinput 60V~90 VDC, Output 12V, Wattage 200~250W

Please suggest a suitable part ( Do suggest an automotive qualified part ALSO. if available).

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LM5163-Q1: LM5163 about CIN cap choose

September 10, 2019, 10:49 pm
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Part Number: LM5163-Q1

Dear,

our client was use LM5163-Q1, also we fill up excel file as attached, than we find some question as below:

1. we saw the LM5164-Q1 EVM , C8=33uF, But we use excel tool CIN CAP value only need >2.2uF

so LM5164-Q1 EVM parallel CIN cap  C8 & C9 & C10 was must need?


2. about CIN Datasheet 8.2.2.5

if the LM5163-Q1 is not located within approximately 5 cm from the input voltage source.

it is mean over 5cm, suggestion CIN more higher 2.2uf right?

3. about Datasheet 9. Power Supply Recommendations
avoid VIN each time the input supply is cycled ON and OFF. The parasitic resistance causes the input voltage to dip during a load transient. If the converter is operating close to the minimum input voltage, this dip can cause false UVLO fault triggering and a system reset.

so it is add CIN reason? if we do not need UVLO function , could we can remove CIN cap?

if any suggestion, Please advise me.

Thanks,

Best regards,

Lawrence.

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LM5180: VCC voltage

September 10, 2019, 11:02 pm
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Part Number: LM5180

Hi,

What voltage is internal VCC regulator?

Best Regards,

Kuramochi

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WEBENCH® Tools/LM5170-Q1: LM5170 support buck-boost converter when Vin is vary range (52V drop to 45V)

September 10, 2019, 11:19 pm
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Part Number: LM5170-Q1

Tool/software: WEBENCH® Design Tools

Hello, 

TI FAE suggest us to use the LM5170. But I didn't find any application to improve it.

Only found 48V to 12V EVM board.

Spec: Input voltage source is 52V~45V. Output voltage set 54V. Pout is 3KW. Iout is 55A.

Do you have any idea about this application? Or any suggestion?

Please give me the light.

Thanks.

Aska

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LM76202-Q1: Power management forum

September 10, 2019, 11:23 pm
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Part Number: LM76202-Q1

HI 

When OVP occurred how fast will the output turn off ?

is it 2 us as shown in yellow color below ? thanks!

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BQ24297: BQ24297 REG07[5] BATFET_Disable

September 10, 2019, 11:25 pm
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Part Number: BQ24297

Hi Team,

I have a question about BQ24297 REG07[5] BATFET_Disable.

When charging done, if charge voltage set 4.4V, REG04[0] VRECHG, Battery Recharge Threshold, set 0 (Default: 100 mV),

Before battery voltage lower than 4.4V-0.1V=4.3V, this moment BATFET should be turn off because into recharge range.

This time REG07[5] BATFET_Disable bit should be 0 or 1?

Thank you.

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