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TPS561208: Switcher cycles on and off and then dies

September 27, 2018, 7:39 pm
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Part Number:TPS561208

Our school group is designing a tone generator for a class project. We ran the WebBench tool to help us specify parts for the voltage regulation circuit and decided to go with the TPS561208 switcher to produce a 3.3V output. We followed the suggested schematic and PCB layout (see attached) from the TI datasheet. We got our PCB built and started soldering on components this week. We gave it an initial test and our only problem seems to be with the 3.3V Switcher. We did a simple finger test on the component and it gets really hot on startup and then switches off. We have checked the schematic many times, read through the datasheets, checked for solder bridge shorts, etc and found nothing.We replaced the TPS561208 with a new part and the problem was repeated. We built just the 3.3V switcher schematic components on a separate board to isolate the problem and the problem was repeated. The component, new, out of the packaging reads about 300K ohms output to ground. After it has been briefly given power (6 or 7 Volts only, full voltage will be 12 V) this is reduced to 3 to 6 ohms to ground. When the part is removed from the board there is no longer a short between the 3.3V and ground plane. We took some data with the oscilloscope (see attached). You can see the switcher turns on and comes up to the full 3.3V output, but then overheats and cycles on and off a bit before it dies.

Our current point of contention is the ESR of the passive components around the switcher. We only spec'd the TPS561208 from the WebBench tool and did not realize the passives might be critical also. We are using a 3.3uH inductor with about 70 miliohms ESR (TDK VLCF4020). The coilcraft inductor in the WebBench tool was only about 18 miliohms ESR. We chose X5R caps, but the ESR for them is not specified in the datasheets. Could high ESR  passives cause this problem?

Any help is appreciated. If I left anything out and you need more specifics, please ask.

It is a 4 layer PCB. The blue is on the bottom side. There is a ground plane and a 3v3 power plane in between top and bottom.

This was taken after the fault occurred. The yellow is input. The green is output.

Yellow input, Green Output

Yellow input, Green output. This was taken with a second, new chip. This should show the fault occurring.

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CC8530: support CC2592?

September 27, 2018, 7:39 pm
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Part Number:CC8530

Dear TI Experts,

My customer want to design CC8530 plus CC2592 other than CC2590 to increase output power, however, in the PPW's radio item, only CC2590 and CC2591 are on the drop down list.

Is it possible to use CC2592 while keeping CC2590 in PPW configration? Thanks a lot.

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TRF7963A: Schematic check request

September 27, 2018, 7:40 pm
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Part Number:TRF7963A

Hi,

I got customer schematic of TRF7963A. This is based on our reference schematic.
Could you review it and give me your feedback?
(Please visit the site to view this file)
To keep customer confidential information, only RFID part is attached.
If you need full schematic, I can send it by e-mail.

Thanks and regards,
KoT

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TMUX6104: MUX selection for replacing FSA2567UMX

September 27, 2018, 7:49 pm
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Part Number:TMUX6104

Hi Team,

Would you pls help check if we have suitable device to replace FSA2567UMX? Thanks for the support.

Best regards,

Sulyn

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TLV759P: Dropout Voltage

September 27, 2018, 7:52 pm
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Part Number:TLV759P

Hello,

My customer is considering about Vdo of TLV759P.

Their requirements are as follows.

Vin : 1.8V

Vout : 1.35V

Iout : 0.6A (max)

It is written In datasheets as follows.  Vdo = 580mV(max)  1.2 V ≤ VOUT < 1.5 V @ 1A

Here is a question,

What is the max value of Vdo when the output current is 600mA ?

Regards

Taichi Nakamura

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MSP430FR5969: Exporting GUI composer widgets to Energia Desktop view

September 27, 2018, 7:53 pm
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Part Number:MSP430FR5969

I am trying Exporting GUI composer widgets to Energia Desktop view. Is it possible?

I can export to Stand alone and to CCS but not to Energia.

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BOOSTXL-3PHGANINV: Can I use BOOSTXL-3PHGANINV together with TMS320F280039C to drive DC brushless motor?

September 27, 2018, 8:11 pm
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Part Number:BOOSTXL-3PHGANINV

From the manual we can see that 3PHGANINV is design for AC brushless motors which have sino back EMF. But Can I use BOOSTXL-3PHGANINV together with TMS320F280039C to drive DC brushless motor too?

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Linux/AM4378: reserved pins open?

September 27, 2018, 8:17 pm
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Part Number:AM4378

Tool/software: Linux

Hi,

    I found those pins AE7，AE8,AE10,AE11,AE12, AD1,AD2 AD7  connnected some signals and parts on the “Pg20: Secondary RTC Osc/Ctrl” on the  AM437X_GP_EVM_3K0006_REV1_4A.DSN， but on the AM4378 datasheet ,those pins are reserved.

     Can I let those pins open in my design?

Best wishes!

Jianhua Yuan

 

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AMC1301, AMC1311

September 27, 2018, 8:24 pm
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Hi there,

Is there for sell TI isolated amplifiers EVM in stock with fully differential analog input and single-ended analog output for current and voltage measurement or a combination of EVMs in stock that can do that?

I would like to measure AC current 0-200A; 0-10kHz; AC voltage 0-1000V; 0-10kHz.

Regards,

Dimitar

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TPS2546: USB ground connection for ESD/Surge test

September 27, 2018, 8:40 pm
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Part Number:TPS2546

Hi,

My customer used our TPS2546 for USB BC1.2 charging. While they have questions related the USB ground connection for ESD/surge test. How to connect the USB signal ground to the case ground of equipment for better ESD/surge test?

 

Can you share any experience of that?

Many thanks.


Brian Zhao

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UCC27324: H-Bridge to drive a TEC (Peiltier)

September 27, 2018, 8:43 pm
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Part Number:UCC27324

Hi,

One of our customer is working on a design to drive a TEC.  They will drive the TEC with a 14V supply and to a max current of 10A.  A block diagram is shown as follow:

A H-bridge is required to switch the direction of the current to the TEC.  Switching speed is not critical (few seconds per cycle).

I would like to recommend UCC27324 gate driver and two sets of CSD87333Q3D to form the H-bridge circuit.

Will these combination be good for their requirement ?

Regards,

CM.

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TPS54202H: I want to know how to test TPS54202H OVP function？

September 27, 2018, 8:44 pm
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TM4C123GH6PM: How to modify the interrupt vector table address in the main program？

September 27, 2018, 8:49 pm
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Part Number:TM4C123GH6PM

Hi all：

My project uses bootloader and a app with ucosIII. Bootloader I deposited it in flash 0x0 -0x7fff. My app is stored in 0x8000.

But after bootloader jumps to the App entry address, APP is unable to run. I look at some relevant examples.

There is a hint that I need to set interrupt vector table addresses at the entrance of the main program.

For example, MSP430： SCB->VTOR = FLASH_BASE | 0x10000;

For example, STM32:    NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x8000);

Is there a similar way for TM4C123 to let me set up the interrupt vector table address in the application? Thank you very much！

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TMS320F28335: how to ues MTBF / FIT parameter of TMS320F28335 posted in TI.com?

September 27, 2018, 8:56 pm
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Part Number:TMS320F28335

Dears,

     My product is Train Signal Control System, The main CPU is TMS320F28335.

As of reliability, we must submit MTBF / FIT to End Customer. But  my MTBF / FIT parameter is 10 times higher than the reference value as below.

I want to know how to ues MTBF / FIT parameters of TMS320F28335 like this. and could you show me the MTBF / FIT parameters when Conf level is 90%?

Thanks a lot.

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INA301: output offset add

September 27, 2018, 9:00 pm
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Part Number:INA301

hi

IN301 is a fix gain opa without outside Resistor. how can I add an offset to the output like the normal opa by adding a ref in the positive opa input without affecting the gain? thanks a lot.

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LMV612: Is there an op amp pin floating in the dual channel, which will cause the normal operation of the op amp to fail?

September 27, 2018, 9:01 pm
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Part Number:LMV612

LMV612 only uses A, B is not used, but forget to process B when design, resulting in +INB, -INB, OUTB are all floating state, what will result in this, A will be invalid?
The product is about to be released and does not want to modify the principle and PCB.

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TLC5926: Daisy chain setup timing potential problem

September 27, 2018, 9:02 pm
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Part Number:TLC5926

Minimum tPHL4 in the datasheet is not specified while tSU(D) is min 7ns.

Above could indicate a potential daisy chain problem (or at least the device is not daisy chain friendly). How could multiple devices be safely daisy chain with above params?

What is the recommended way of daisy chain for TLC5926 (mainly related to address setup timing violations on second device which is fed from SDO of first one)?

We have some real problems in daisy chaining 8 of these devices where first 4 seems to work but last 4 cause some garbage on the 7 segments displays they drive.

Valentin

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UCD3138: ROUND in PID filter

September 27, 2018, 9:02 pm
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Part Number:UCD3138

Hi Sir:

it's said that for Differential Branch, 32 bit result would be rounded back down to 24 bits, how does this work? by right shift of 32 bit result?

"This D alpha branch acts as an integrator
on the output of the D stage. With each filter calculation, the 24 bit result of the previous D and D alpha
calculation is multiplied by the 9 bit Kalpha (Kα). This gives a 32 bit signed result. To match the 24 bit data
path, this must be rounded back down to 24 bits."

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TPS7A90: MIN/MAX value of V_HYS(PG)

September 27, 2018, 9:07 pm
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Part Number:TPS7A90

Hello,

 

I have a question about PG pin hysteresis, V_HYS(PG).

For V_HYS(PG), only TYP value, 1%, is defined in the datasheet like the below.

Then are MIN and MAX values of this V_HYS(PG) available?

 

 

 

Here is the background of this question.

The threshold from PG low to PG high is defined as V_IT(PG) + V_HYS(PG).

Then because min/max values of V_HYS(PG) are not defined, we are not sure the min/max threshold values from PG low to PG high.

I believe it never happens, but no min/max definition means it could technically happen that PG never go to open drain when V_IT(PG) + V_HYS(PG) is over 100%

or PG is always open drain when V_HYS(PG) is minus %.

 

So my customer is requesting to add min/max to the datasheet.

Or could you show me something data to make clear min/max value?

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RTOS/EVMK2G: printf behavior in usb drv library

September 27, 2018, 9:09 pm
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Part Number:EVMK2G

Tool/software: TI-RTOS

Hello!

I am extending the usb driver code that came with the k2g pdk code so that I can plug in a usb MIDI controller device to the board. The version of the pdk I am using is 1.0.7.

When I add printf statements to the usb driver code, the code that was cloned from pdk_k2g_1_0_7\packages\ti\drv\usb, my program crashes if I use formatted strings like this: 

                 printf("Here is a value: %d!\n", value);  // This prints the string to the console and then crashes

My program prints to the console as expected: "Here is a value: 0!" and then crashes.

It works fine if the the string is not formatted with an argument. This works fine without crashes:

                 printf("Here is a string, no values!\n");  // This works, no crashes!

I am building the usb code outside of ccs, using gmake. My main code that links the usb library is built with ccs and printf works as expected. I am wondering what is causing this behavior. Is the usb code using a different printf function? Is there a memory access issue going on? How can I tell?

Thanks for your help!

Andrew

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