TPS92641EVM: Current waveform confirmation

May 21, 2019, 4:46 pm

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Part Number:TPS92641EVM

Hi Team

My Customer is facing the issue so please advise below inquiry.

When an electronic load was connected to the output of the evaluation board of the TPS92641 and the operation was confirmed in CV mode, it could not be operated normally.Please tell us if there is a technique to make it work properly.

I tried to confirm the operation by connecting 19 bridge diodes in series to the output. The waveform is very dirty, is this normal?
Sorry to trouble you, but please check the waveform below.

Thanks

Best regards,

Shidara

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Question of LM27762

May 21, 2019, 5:31 pm

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We have question about LM27762.

Can we use this IC under following conditions?

Vin=5V

Vout(+)=3.3V

Vout(-)= -5V

Iout=100mA

Best regards,

Takahiro Nishizawa

BQ24133: Pls help to review the schematic

May 21, 2019, 5:52 pm

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Part Number:BQ24133

Hello,

Pls help to review the schematic as below.

TPS7A7200-EP: dual supply system

May 21, 2019, 5:55 pm

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Part Number:TPS7A7200-EP

I am using this part in a dual supply system where the regulated load is returned to a negative supply.  Do I need to clamp the OUT or FB with a diode to ground for this part as you suggest in some of your other linear regulator data sheets.  How can I tell if that is needed with your other linear regulators for future designs?

TPS54331: Risk Assessment: TPS54331 output connected to 3.9V while no voltage input

May 21, 2019, 6:58 pm

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Part Number:TPS54331

Hi Team,

My customer has a TPS54331 design, it is used to get an output of 3.9V from the input 15V. 

But there is a backup power from the battery, which is also 3.9V, directly connected together to the output of TPS54331. 

In this case, if there's no 15V input to the TPS54331, The battery will provide 3.9V to the loading, as well as the output PIN of the TPS54331. 

Then in this test, they found that the input PIN of the TPS54331 is ~3.5V. 

So here comes the problem:

1. Risk assessment: is it all right to directly give the TPS54331 output PIN with 3.9V while no input voltage? 

2. why there would be 3.5V in the VIN of the TPS54331 when output has 3.9V. The voltage of the input PIN seems coming from the chip internal sourcing from the output 3.9V.

BQ27Z561: Is there need to calibrate CC offset and Board Offset for BQ27Z561？

May 21, 2019, 7:01 pm

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Part Number:BQ27Z561

Hello,sir,

I am working on automatic calibration for BQ27z561 , and I do the job by refer to the TRM (whose revision is: Literature Number: SLUUBO7 June 2018 ). From the chapter 12.2 (Current Calibration) , there is not any description about CC OFFSET and BOARD OFFSET calibration,  SO, Is there need to calibrate CC offset and Board Offset for BQ27Z561？ if yes, please kindly explain the reason. Thanks.   if it need to be done ,  what dodument should i take?  

I do the same job for BQ28z610 several weeks ago, I guess there are some big difference  between those to Part about calibration. isn't it?

Thanks In Advance

BQ25895: maximum current of Sys - pin can be supported

May 21, 2019, 7:43 pm

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Part Number:BQ25895

hello all, 

sorry, i'm a beginner in power management system.

i want to create battery management system which that system can charges a battery 18650 ( li-ion ).

my system use 3.3 to 4V and at least 4A. 

is BQ25895 can support it ? or there is another option for part that i can be use ??

thanks

TPS61280A: start up current

May 21, 2019, 8:05 pm

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Part Number:TPS61280A

In the datasheet it's said:

The TPS6128xA automatically powers-up as soon as the input voltage is applied. The device has an internal soft-start circuit that limits the inrush current during start-up. The first phase in the start-up procedure is to bias the output node close to the input level (so called pre-charge phase). In this operating mode, the device limits its output current to ca. 500mA. Should the output voltage not have reached the input level within a maximum duration of 750µs, the device automatically increases its pre-charge current to ca. 2000mA. If the output voltage still fails to reach its target after 1.5ms, a fault condition is declared. After waiting 1ms, a restart is attempted. When output voltage being close to Vout, the device enters into boost startup mode (for Auto Mode only). The device provides a reduced current limit of ~1.25A (I2C programable for TPS61280A to set it back to normal current limit) when the output voltage is below pre-set voltage to avoid the high inrush current from battery. During start-up, it is recommended to keep DC load current draw below 250mA.

I have several questions:

1. There are two phases of the start-up procedure,

    pre-charge phase: output voltage gradually increases to the same as input voltage.

    boost startup phase: output voltage from the same as input voltage to VOUT set by register.

Do I understand correctly?

2. "The device provides a reduced current limit of ~1.25A (I2C programable for TPS61280A to set it back to normal current limit) when the output voltage is below pre-set voltage"

For example, if I set VOUT to be 3.8V, ILIM to be 2A through I2C, the current limit will be 1.25A before the output voltage reaches to 3.8V, and will be 2A after the output voltage reaches 3.8V?

3. "During start-up, it is recommended to keep DC load current draw below 250mA"

Why it's 250mA? I don't understand. I think it should be 1.25A as I discussed in question 2.

For example, if the load current>1.25A, the output voltage will never reaches the VOUT set by the register, right?

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UCC28950: UCC28950 OUTD narrow pulse during start up

May 21, 2019, 8:23 pm

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Part Number:UCC28950

Hi Support team 

my customer was suffered OUTD narrow pulse during problem during start up 

may i have your take a look and kindly advice how to prevent it 

Orange CHA = OUTD

PINK CHB = OUTB

Purple CHC = OUTC

Green CHD = OUTA

Lead-acid battery charger

May 21, 2019, 8:51 pm

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Hi Team,

1. What is the charging process of Lead-acid battery? Just like CC/CV for Li-ion?

2. If Lead-acid battery need CC/CV like Li-ion, than every charger which charging voltage could be adjusted should suitable for Lead-acid, why the charger that TI list are almost buck-boost topology?

Thank you very much!

C.T.

UCC25600: Can UCC25600 be used for full bridge topology?

May 21, 2019, 9:12 pm

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Part Number:UCC25600

 Hello guys,

 One of my customers is considering using UCC25600 with full bridge topology like the attached pdf file.

 Could you please give me your answer or advice to the following  questions?

 Q1. Can UCC25600 be used for full bridge topology?

 Q2. If the answer to Q1 is Yes, do you have any reference schematic?

 Q3. If the answer to Q1 is No, could you please tell me any full bridge controller IC you recommended?

 Your reply would be much appreciated.

 Best regards,

 Kazuya Nakai.

/cfs-file/__key/communityserver-discussions-components-files/196/UCC25600_5F00_FullBridge052219.pdf

 

Find suitable DCDC

May 21, 2019, 9:24 pm

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I am looking for DCDC for below. I already checked it on TI website. I couldn't find what i want.

especially, can you make -250V using charge pumpig with your any DCDC?

because there is no DCDC which can make -250V standalone.

please give me good advice for below DCDC

1st)

- Vin : 3V ~ 12V

- Automotive

- Vout : 132V / 0.01A

- Automotive

2st)

- Vin : 3V ~ 12V

- Automotive

- Vout : -250 / 0.01A

- Automotive

Question of negative voltage output

May 21, 2019, 9:31 pm

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We are looking for the IC under the following conditions.

Vin= -15V

Vout= -12V

Iout=500mA

Please tell us the recommended device.

(DCDC converter or LDO and so on)

Best regards,

Takahiro Nishizawa

Solar battery connection

May 21, 2019, 9:39 pm

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I am using 150W solar panel and 45A 12v starter battery for my small domestic off grid system

Now I need to increase one more battery to the system 

Q1. What is the best way that I should connect the battery to achieve best efficiency in parallel or series 

I know that when i connect series the output voltage go up to 24v that  does not a matter for my system 

Please advice 

CSD19532KTT: How to make the circuit output pulsed voltage waveform with MOSFET?

May 21, 2019, 9:48 pm

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Part Number:CSD19532KTT

Hello, TI engineers !

I am intending to obtain pulsed voltage with MOSFET, and the chooper circuit I designed is as followed. To ensure the MOSFET can be turned on, the Source terminal of the FET is connected to the gate driver GND. The gate-source voltage waveform is effective to drive the MOSFET, which is pulse voltage of 5V with duty 20%. 

The output voltage is obtained from Source and GND of supply voltage Vsup (DC power).

When the output of gate driver is high, the MOSFET is conducting so the Source terminal voltage is equal to Vsup.

But when the output of gate driver is low, the MOSFET is working in switch-off state. Then, the voltage difference between Source terminal and GND of Vsup is not sure because there is no common between the two terminals. 

When suppying pulse control signals to the Vin, the output voltage Vout is always high and equal to Vsup, rather than chopped pulse voltage as intended.

What is the problem of this circuit and what should I do to output pulse voltage?

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BQ30Z554-R1: REG33

May 21, 2019, 10:01 pm

≫ Next: UCC25600: How does UCC25600 avoid shoot through of external MOSFETs(High side and Low side NMOSFETs)?

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Part Number:BQ30Z554-R1

Hi Team,

Good day

I'm using bq30z55 for NB battery pack design.

Customer requests 3.3V output from REG33(pin 24) for system RTC power by connector

Maximum current is under 1mA

Any idea?

Thanks

Alec

UCC25600: How does UCC25600 avoid shoot through of external MOSFETs(High side and Low side NMOSFETs)?

May 21, 2019, 10:03 pm

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Part Number:UCC25600

 Hello guys,

 One of my customers wants to get the answer to the following question about UCC25600.

 Could you please give me your answer?

Q. How does UCC25600 avoid shoot through of external MOSFETs(High side and Low side NMOSFETs)?

    Or does UCC25600 not have any function for avoiding shoot through?

 Best regards,

 Kazuna Nakai.

TPS54160A: About Production Burn In/Test

May 21, 2019, 10:49 pm

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Part Number:TPS54160A

Hello,

 

Regarding to burn-in test data on TPS54160ADGQ, my customer is asking a question.

(Question)

Do you have a burn-In test data? If so, could you please tell me about temperature ranges,

test time for burn-in?

I think that it might not have a data because of general purpose device.

Just in case. I will ask about that.

 

Regards,

Tao 2199

TPS23841: Do you have any PSE device except TPS23841 for PoE?

May 21, 2019, 11:10 pm

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Part Number:TPS23841

 Hello guys,

 One of my customers is looking for a PSE device of PoE.

 They want to use a device which meets to the follwoing spec.

 ----------------

[Spec]

  Input : 24V

  Output : 48V/350mA

  Meet to IEEE802.3af standard.

  PSE side device.

------------------

  If you don't have any other device, can I recommend TPS23841 to them?

 Also when they use the device, they may need some support for software to control it.

 Do you have any capability of software support for them to control TPS23841?

 Your reply would be much appreciated.

 Best regards,

 Kazuya Nakai.  

TPS61178: Without Load Disconnect Function, EN=H,Output=16V,EN=L,Output=0V?

May 21, 2019, 11:18 pm

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Part Number:TPS61178

Hi,

I use TPS61178 without load Disconnect function, But I hope the EN signal can control the ouput voltage. Described as follows:

If EN=H(3.3V), Output=16V,

If EN=L(0V), Output=0V,  Right ?