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UCC28070: why current synthesizer has output A and output B?

November 30, 2018, 2:16 am
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Part Number:UCC28070

Hi, 

From my perspective, the PFC controller only need to get the information of input current, input voltage and output voltage.

The reference of input current should be the same phase with input voltage to keep PFC=1.

So we should monitor the total input current and give the current information to both phase A boost control loop and phase B boost control loop.

But in our datasheet, we would give OutA to phase A boost control loop, OutB to phase B boost control loop.

What's the difference of OUTA and OUTB?

And what's the relationship between OUTA, OUTB and total input current?

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WEBENCH® Tools/LM25037: Not in WEBENCH

November 30, 2018, 2:27 am
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Part Number:LM25037

Tool/software: WEBENCH® Design Tools

Hi,  I'm curious why the LM25037 isn't offered in WEBENCH.

Is there a spread sheet or any other aid to help design this part into a product?

Thanks,

---Keith---

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LMR14030: LMR14030 simualtion results not satisfactory.

November 30, 2018, 2:42 am
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Part Number:LMR14030

My input specifications are.

1.       Generate a 5V +/- 3% output voltage ; output ripple~50mV or less if deemed necessary

2.       Nominal operating range 9-16V

3.       Output current ~200mA

4.       Switching frequency: Around 500 kHz – you can increase the Fsw up to~2MHz if the components needed for lower Fsw are too big.

For the above requirement i designed the inductor and capacitor values as 85uh and 4.7uf.But with these values i am not getting the continous inductor current cylces.

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LM5023: QR pin not used, could QR pin connect to ground directly?

November 30, 2018, 2:51 am
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Part Number:LM5023

Hi Team,

My customer doesn't use QR pin of LM5023.

Could he connect QR pin to ground directly?

Is there any concern?

Please advise. Thank you.

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TPS62175: Vout = 5V Load and Line Regulation Data

November 30, 2018, 3:03 am
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Part Number:TPS62175

Hi, 

In the datasheet of the TPS62175 datasheet, we provided the Vout = 3.3V Load and Line Regulation data. Can you help to advise the corresponding data for Vout = 5V? 

Thank you.

Best Regards, 

Dunman

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LM3481: EVM circuit

November 30, 2018, 3:21 am
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Part Number:LM3481

Hi 

I want to ask about the circuit of LM3481 EVM.

What are the functions of the following yellow area circuits?

Should they be added to output high voltage applications?

Thank you

Jerry

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BQ25505: Can’t ever achieve Batt-Ok

November 30, 2018, 3:56 am
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Part Number:BQ25505

Having difficulty with a design meant to charge a typical 3.6v Lipo (650mAh) single cell from a solar panel that has been clamped down to 5.1V, (oc=7.8v) On all tries of the circuit we have VBAT_OV=4.1v First try of the circuit we had VBAT_OK set to 3.5V and VBAT_OK_HYST set to 4.0V. The battery never got past a charge of 3.4V Second try we had VBAT_OK set to 2.5V and VBAT_OK_HST set to 3.5V. This time, the battery could not charge past 3.2V. Any ideas?
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BQ24170EVM-610-15V: What's the purpose of R22 resistor

November 30, 2018, 4:16 am
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Part Number:BQ24170EVM-610-15V

Hello, 

I am wondering what is the purpose of R22 resistor. Is it use to bypass D3 diode? But then again, what is the reason for bypassing this diode? 

Best regards,

Jakub



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TPS23880: manually enable port

November 30, 2018, 4:54 am
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Part Number:TPS23880

Hi,

Two short questions,

1. which register can enable/open the PSE port (force open) without a PD presents?

2. Which register can read the input PSE voltage(generally 48V)?

Thanks.

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BQ25504EVM-674: BQ25504EVM-674

November 30, 2018, 5:13 am
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Part Number:BQ25504EVM-674

Hi, 

I'm looking forward the reference layout file for bq25504 evm in PADs or Allegro, 

can you please help provide it? Thanks.

BR,

Ya Ting, Chang 

PhD Student, KU Leuven

e-mail : ychang@esat.kuleuven.be

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TPS92602-Q1: Wrong overcurrent detection

November 30, 2018, 5:46 am
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Part Number:TPS92602-Q1

My design consists of 2 TPS92602-Q1, which gives 4 LED channels in total. If I turn on all 4 channels at the same time with full power (100% duty), the 4th channel seems to detect overcurrent (DIAGx measured at 3.3V). This doesn't happen if  all channels running with lower duty or if the 4th channel is running without the others.

I suppose this could have something to do with unwanted noise. Is there a good way or starting point for finding the root cause? What could I try?

Thanks for any help in advance!

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BQ40Z80: Shutdown behaviors and indication

November 30, 2018, 6:33 am
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Part Number:BQ40Z80

I have a few questions regarding shutdown with the BQ40Z80:

  1. Is there an signal that will tell my MICRO that it’s in shutdown? Does PBI (pin 31) go to zero when in shutdown?
  2. If I command shutdown via the Shutdown Present Input (pin 17), will PBI also turn off?
  3. If I command shut down via the Shutdown Present Input (pin 17),will it latch off?
  4. Once in shut down, will a voltage at the PACK input (pin 25) will wake it up?

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UCC28780: Topology check

November 30, 2018, 6:35 am
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Part Number:UCC28780

Hi team,

Does ACFlyback suitable for DCDC converter? 30V to 14V 110W

Thanks

Tom

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BQ2083-V1P3: On Line Gas Gauge Calculator

November 30, 2018, 6:47 am
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Part Number:BQ2083-V1P3

Have submitted required files for Gauging Parameter Calculator for CEDV, but received "Error: Computation was not successful, but the specific reason was not identified. Please check that all files are prepared according to the documentation. The support personnel have been informed." Have actually been through several attempts, and have found errors in each one. First it was a csv file with text still in the file, then it was typos in the cofig.txt file. I have reviewed them again, but can no longer find any errors. Any help you could provide would be greatly appreciated.

 

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UCC2897A: Inductance setting

November 30, 2018, 7:44 am
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Part Number:UCC2897A

Hi

My Customer is current 22W active clamp forward circuit configuration of UCC2897A.

The first problem I found is that the output inductor is applied to 22uF and the circuit oscillates after a certain time, when the output capacitor is 540uH (270x2).

Conversely, lowering the output inductance to 1.5uF improves the problem.

I implemented the circuit with caculator and webench.

In this circuit, the output inductor was increased to about 120 uF and the output capacitor was reduced to 10 uH.

However, testing the current board and increasing the output inductor will cause the circuit to start oscillating at 5uH.

Can the trans L value affect this? Or what should we look at? We tried to change the trans L value, but there was no big change.

Is it possible to reduce the inductance to 1.5 uF, which is different from the calculated value?

I attach the test contents of the customer's company.

The current customer plans to design 44W through the next version development.

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TLV707: What is the expected behavior of the TLV707xx if VIN goes below VOUT

November 30, 2018, 8:59 am
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Part Number:TLV707

Hello,

I have a customer planning to use the TLV70730 in an application.  However, there are times when his battery may dip below 3.0V say down to 2.8V.  He sees the output voltage follow the input voltage down with a slight drop.  Is it reasonable to say that in the condition of VIN<3.0V in the case of the TLV70730 that the TLV70730 will regulate to the input voltage minus the drop out voltage and this will work down to an input voltage of 2.0V?  Do we have any graphs or data for this condition?

Thanks for your feedback.

-Will Jarrett

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Flyback controller for USB

November 30, 2018, 9:17 am
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Hello,

I have a task to design an isolated .25watt, 24V supply to run off of USB.  My difficulties are two:

1. Identifying a controller that would operate from 5V.

2. Limiting the switch current such that the USB 100ma current limit is not exceeded (i.e. during inrush to the output capacitor)

You're suggestions are welcome.

Mike Fortner

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BQ25010: can i short USB, BAT/OUT1, BAT/OUT and CE to a 6.8v battery

November 30, 2018, 9:17 am
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Part Number:BQ25010

Hi, I am trying to modify an old design using bq25010.  In the old design, CE is grounded, and it use bq25010 to charge a 3.7v Li battery, as well as generate 3.3v for my board.

for my new design, I need to use a different 6.8v Ni-MH battery with an external charger.   But I do not want to change my old board design, so I will keep the bq25010.

so I have two questions:

1. I am thinking of shorting 4 pins:  USB, BAT/OUT1, BAT/OUT and CE to the new 6.8v battery, is it OK?  basically I am using bq25010  only as a buck converter to generate 3.3v for my board. 

2.  if I tie EN and CE pin permanently to 6.8v,  will it be ok?  any long term reliability issue?   the datasheet only specify absmax for EN is 7v, but didn't specify absmax for CE pin.

Please advice.

Thanks.

John

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BQ25505: AC input source 10 - 1000mV ?

November 30, 2018, 9:40 am
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Part Number:BQ25505

Hello,

We are looking at using an energy harvest with ~1k impedance range, AC, 10’s to 1,000’s of mV but less than piezo.

So, we need AC-capable and ultra-low startup voltage.

Would you have an IC or bridge recommendation that would work?

Thank you, Keith 

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TPS543C20: Transient Response

November 30, 2018, 12:17 pm
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Part Number:TPS543C20

Hello,

Is there a way I can add a compensation circuit to the voltage feed back pin to get better transient response?  If so, how?

If not, is there anything else I can do to improve transient response?  And if so are there any trade-off in implementing such a method?

Thanks,

HSG

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