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EMB1428Q: emb1428 EN DONE DIR DIR_RT set up problem

August 1, 2019, 8:17 am
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Part Number: EMB1428Q

Hi

I currently using EMB1428 alone does not match EMB1499.

How to set EN ,DONE, DIR, DIR_RT these pins?

If it need to reverse,what should I do?

Is it a normal NOT gate or a specific one?

Does the official have a reference code?

I still have a problem.When I send 0x01 and the data receives fault[3:0] as 1010 is correct.

Can I see a waveform output between gate0 and sourse0?

I did not connect the MOS, just made a EMB1428 only board for testing charge pump and SPI and observe the reaction of the switch.

Thanks

Sun

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TPS23753A: TPS23753A Efficiency

August 1, 2019, 8:27 am
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Part Number: TPS23753A

Hi TI sir

I made a TPS23753A board and  found the efficiency are as below

the design concept is Vin=48V and Vout=5V

1. when Pout=3.31W(5.05V*656mA), Pin=5.29W(48.06V*110mA, ), the efficiency is 63%

2. when Pout=3.98W(5.05V*789mA), Pin=5.82W(46V*126.5mA, ), the efficiency is 68%

3. when Pout=7W(5.05V*1391mA), Pin=9.59W(45.69V*210mA, ), the efficiency is 73%

is it reasonable??because I don't see the efficiency table in TPS23753A datasheet

thanks

David

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LM2663: LM2663 SD pin connection

August 1, 2019, 8:36 am
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Part Number: LM2663

The LM2663 datasheet says the SD pin is connected to GND, but does that mean there must be an external GND connection?

The sample schematics in the datasheet do NOT show an external GND connection, except in the test circuit (pulled down by 1M resistor)

-Dave

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BQ24171: Needed AVCC off period for device reset

August 1, 2019, 8:48 am
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Part Number: BQ24171

How long period should we off the AVCC for device reset?

Is bq24171 done reset if AVCC drops below 3.37V even for a moment? Or should we wait for a while?

If we should wait, please let me know the period.

Best Regards,
Kohei Sasaki

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BQ34Z100-G1: Current/Average Current Sample Rate

August 1, 2019, 8:55 am
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Part Number: BQ34Z100-G1

Hi,

Please could you provide some more information on the 'Current' and 'AverageCurrent' calculations used by the BQ34Z100-G1. I understand both these fields are updated every 1 second, but how are the values reported derived by the BQ?

Is ‘Current’ an instantaneous current reading or is it for example the average current seen over the 1 second period?

Is ‘Average Current’ a moving average over for example a 30 second period? ‘Average Current’ certainly seems to take a long time to update when a battery is connected to a load.

Thanks

Matt

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TPS56121: Overshoot and undershoot issues - design review

August 1, 2019, 8:52 am
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Part Number: TPS56121

Hi,  

We are having the high overshoot and undershoot over the 3.3V output voltage.

TPS56121 on our board has the following properties :

·         Vinnom=12V , Vinmin=11V, Vinmax=13V , Vout=3.3V , Iout-peak(max)=12A for 10u seconds,  Iout-operation(max)=10A 

Below the schematics and feedback loop compensations values and bode plots.

Can you please provide design review regards the data below, and advise how the design can be improved in order to resolve the high overshoot and undershoot issues ?

The 3.3V output is connected on our board to 4x loads. Each load has a peak of 3A during 10u seconds on the 3.3V.

Each load is connected, on its input 3.3V pins, to the circuit below (Ferrite bead and the capacitors) as you can see below:

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UCC28950: Negative voltage on CS pin.

August 1, 2019, 9:08 am
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Part Number: UCC28950

Hi team.

I'd like to know about the CS pin.

In our customer's use case, a negative voltage is applied to the CS pin.

It was about -0.8V when we measured.

I know that the absolute maximum ratings has been exceeded, will the device broken in this case?
Also, does it work unexpectedly?

The data sheet contains a diode at CS pin, please tell me the meaning of this.

Sincerely.

Kengo.

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TPS53622: RADDRL AND RADDRH

August 1, 2019, 10:54 am
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Part Number: TPS53622

Hi.

While going through the datasheet we understand to set SVID and PMBus registers addresses we use RADDRL AND RADDRH resistors. in my case RADDRL = 154K and RADDRH= 215K. My question is:

1) Can we use the lower resistor value maintaining the same ratio of RADDRL AND RADDRH.

2) If not, the values of RADDRL AND RADDRH is new component for us, can we combine resistors in series to make the required values e.g. (Use 2 77K resistor for RADDRL) or similar combinations to get those values.

3) What are the tolerances and power dissipation limits for the RADDRL AND RADDRH resistors and package recommendation.

Thanks

Vikas G.

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BQ24232: No output on V(OUT) with V(BAT) at 3.7V

August 1, 2019, 11:05 am
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Part Number: BQ24232

Hi,

It seems I have a few issues using the BQ24232. One of them being that when the battery is connected to V(BAT), the IC does not output anything on the V(OUT) pin. That is true with V(IN) being fed with either 0V or 5V. Despite this, I was able to confirm that the /PGOOD pin goes into low impedance when V(IN) is connected.

Please see the current schematic that I am using:

Any idea what could cause this issue?

Thank you very much,

Xavier

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LM3409HV: Designing for specific switching frequency

August 1, 2019, 11:31 am
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Part Number: LM3409HV

Hi team,

Regarding LM3409HV, I'd like to design around this part and to design for a switching frequency of 20-50kHz (for EMI reasons). I understand that LM3409HV is a controlled off-time device, and that the frequency will shift with the input/output relationship, but if I know my input is consistent at 48Vin and my output is 30-35Vout, then can I achieve a switching frequency of 20-50kHz?

Going through the design equations, it seems I can. None of my calculated toff values violated the toff_max spec, but I want to make sure I'm not overlooking or oversimplifying something.

Thanks!

Brian

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TPS7A16-Q1: transient power rating

August 1, 2019, 12:12 pm
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Part Number: TPS7A16-Q1

Team, 

My customer has the following question: 

I’m wondering if you have something like a Safe-Operating-Area (SOA) curve for the device mentioned in the subject line?  I usually see these curves for things like MOSFETs, but figured it wouldn’t hurt to ask for this device.

Our situation is that we typically have a 28V input and 5V output.  During the 50V 12.5ms transient to 50V, the device will be dissipating more power and I’m wondering if there’s any guidance for transient power rating?

Regards,

Aaron

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LM3549: Timing Questions

August 1, 2019, 1:18 pm
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Part Number: LM3549

Hello!

I am working with a customer who will be using this for a projection application like the chip is designed for. A few questions we have that aren't addressed in the datasheet:

  1. What is the minimum on time for any particular channel? 


When a channel is enabled, what is the typical setting time for the current to reach it's programmed value?


  • Related to #2, is the setting time related to the previous channels current? (Meaning does it take longer when switching from a dim channel to a bright channel vs. when switching from a bright channel to a bright channel?)

Thank you! Let me know if you need any other info.

Regards,
Ryan B.

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LM3466: question on Overhead voltage (Multi-string Current balancer for use with constant-current power supplies) SNOOB96F

August 1, 2019, 12:11 pm
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Part Number: LM3466

I would like to know how much overhead voltage is resulted by application of LM3466? I am using it for a 12 LED in series string. The nominal Vf for 12 LED is 36v. I need the overhead voltage of LM3466 to choose a constant led power module commercially available from Philips, Osram, Meanwell and the like. I am wondering if a power module that can supply up to 39v is sufficient. By the way I am using a 0.4 ohm resistor instead of a 1 ohm resistor. 

Thanks

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TPS56921: why we can't change the switching frequency for this part in the Web bench

August 1, 2019, 2:51 pm
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Part Number: TPS56921

We need to operate this at the maximum switching frequency of 1.6 Mhz as set by a resistor. There is no option in the web bench to change the frequency. It is set at 532 Khz or similar. Can this feature be implemented in the web bench for this part

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TPS63031: Audible noise with power save-enabled

August 1, 2019, 2:52 pm
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Part Number: TPS63031

I have designed a board where I use the TPS63031. The input voltage is from a Li-ion battery (3.3 V to 4.2 V), nominal current is less than 5 mA and max current is 500 mA.

I use an inductor with a Isat = 1.29 A.

There is an audible noise, the noise is higher when maximum current is present.

I attached the schematic of the DC-DC converter.

In the board, I don't have the choice to change to power-save disabled, so, I don't know if it's something exclusive of power save-enabled or  it would have the same problem with power-save disabled.

Could you help me to understand the possible causes of the problem.

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BQ40Z50-R1: AFE Short Circuit Discharge

August 1, 2019, 2:58 pm
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Part Number: BQ40Z50-R1

Hello,

I have 89A set in electronic load.

Scope is reading up to 92A.

Spec: 89A/427µs (+400µs/-100µs tol.) I am measuring more than 1 ms.

 

  • Am I reading the waveform correctly? Please refer picture.

My protections are as follows.

Please let me know how to control ASCD discharge timing by modifying the above values.

Thank you

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BQ40Z50-R1: AFE Short Circuit Discharge

August 1, 2019, 3:02 pm
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Part Number: BQ40Z50-R1

ASCD protections:

Latch limit 0

Counter Dec Delay 10s

Recovery 5s

Reset 15s

Threshold1 76 hex

Threshold 2 77 hex

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TPS56921: 9A or higher load switching regulator with near instantaneous load step response

August 1, 2019, 3:08 pm
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Part Number: TPS56921

HI 

we have this Micro Semi 5A part LX7178-01CSP-TR in our design that has Constant Frequency Hysteretic Control with extremely fast or near-instantaneous load/line step response (time scale is given in 100s of nS for the load step response)

we are looking to substitute it with a 9A output load regulator with 12V input and 1.65V output and I2C control of the output voltage with same kind of fast step response. 

we looked at the TPS56921 but the step response of that is slow. we need to settle to the nominal output voltage value withing a few micro second for a 0-9A load step. 

Could you pleased recommend a suitable part

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bqStudio support for bq40z307

August 1, 2019, 4:12 pm
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  Hi support team!

 We need to update the chemistry on several batteries with bq40z307 as Gas Gauge. And found bqStudio does not have configuration profile for this IC.

Can you please provide us with bq40z307.bqz to complete the task.

Thanks in advanse and best regards!

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ULN2003A: Typical characteristic in datasheet

August 1, 2019, 5:03 pm
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Part Number: ULN2003A

Hello,

I look into ULN2003 datasheet. This datasheet is for some devices, ULx2002, ULx2003, ULx2004. Tyepical characteristic graph is for one devices.

I am looking at Figure 6. input voltage vs input current graph. Figure 19 to 21 show functional block diagram. It looks base resisters are different in devices.

The bottom line, we want to see the maximum input current of ULN2003. Is Fugure 6 used for ULN2003 input current?

Best regards,

Toshihiro Watanabe

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