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BQ35100: Couple of clarifications on EOS

September 28, 2018, 6:56 am
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Part Number:BQ35100

Hi gents,

Rather new to gas gauges so please excuse the questions. Would like to seek some clarification/advice/assistance with EOS mode on the BQ35100 with LI-SOCL2 batteries. I'm using it in tandem with a CC2652.

1) From the documentation, it seems that the process of actually operating the gauge to keep track of battery usage, involves setting GE to high and then triggering gauge start before high load activity. Once this is done, gauge stop is triggered then GE is released. All this is subject to initcomp and g_done flags. For EOS mode, should this be triggered every activity cycle? Or is it alright to trigger every x number of cycles?

2) For some reason, when I trigger gauge start and gauge stop etc through i2c from the target mcu, it works fine if the radio functions (essentially my highest load activity) are not also triggered. However, if I do GE assert, gauge start, radio tx, radio tx, gauge stop and check the control registers at this point, I find bits 3, 4 and 5 raised. These are EOS_BAD_OCV, SOH_MERIT and SOH_ERR respectively. What might be the cause of these? Have not been able to find much information...

3) How do I release the conditions listed in question 2? 

4) What exactly does the reset subcommand (0x0041) actually do? Does it reset all calibration? chemical ID settings? put the chip back in factory defaults? erase any image that may have been flashed previously?

Thanks for the assist... If more details are required, I'll be happy to furnish them. 

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UC2843: Fixed Frequency flyback can it be both CCM and DCM?

September 28, 2018, 7:13 am
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Part Number:UC2843

What are the ramifications of allowing a continuous conduction fixed frequency flyback power supply go from Continuous to Discontinuous operation?  

I've inherited a design where the load on the CCM fixed frequency power supply was significantly overestimated.  As a result the flyback is crossing into DCM operation under actual low load conditions.  Tehere really isn't adequate time to go back to the drawing board to redesign the circuit.  Is this actually Bad?  

All the information I've found seems to assume a supply is designed to be either CCM or DCM.   What issues do I need to look with a supply operating in both modes?  Could there be serious issues that hide right at the threshold between the two operating modes?

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TPS54202: Over shoot in case of startup

September 28, 2018, 7:13 am
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Part Number:TPS54202

Hi all

Would you mind if we ask TPS54202?

Our customer's condition are follows;
<Condtions>
Vin : 12V
Vout : 5V
Iout : 100mA

On the our customer's circuit, after start up, it occurs overshoot, Vout is more than 5.15 for an instant.
Please refer to the attachment file.
(Please visit the site to view this file)

So, we would like to check it using TPS54202EVM, however we don't have this EVM.
If you have the figure of start up with follow condtions, could you share it? 
Vin : 12V
Vout : 5V
Iout : 100mA

We would like to use this data to judge whether the the customer board has some problem or not.
(We assume that the cause of a problem is parasitic inductance or pulse skip mode.)

Kind regards,

Hirotaka Matsumoto

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BQ51003: Wireless charging Rx coil options

September 28, 2018, 7:28 am
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Part Number:BQ51003

We are designing a small wearable device.

We are implementing wireless charging for our LiPo battery. Our charge current will be in the 50mA – 300mA range.
We are exploring ideas and option regarding our Rx coil.

1. Can the Rx coil be implemented on an outside layer of our PCB design?
      Note that this is NOT a standalone PCB, this PCB would also include our overall product design – active components on the opposite side to the coil.
      The obvious issue is Rx coil shielding.We are wondering if a dedicated ground plane, in the layer adjacent to the coil layer, can somehow be used to control or divert the eddy currents to eliminate FO heating

2. Can the Rx coil be implemented as a stand alone flex circuit board design
     This would be stand alone, no other components
     We would add a ferrite sheet to shield the rest of the design

3. If we implemented #2 above, what would be the impact of creating a small hole in the ferrite (shield) material?
     Depending on placement, we may need to add a hole to allow for LED or push-button features.
     Seems like location and size of the hole would be the important details
            Could you provide any general guidance

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TPS22916: On pin input capacitance/input charge

September 28, 2018, 7:54 am
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Part Number:TPS22916

Hello,

Is there any data available for the On pin capacitance or an On pin charge vs pin voltage graph? 

I'm looking at how long the pin will take to charge/discharge with a low current input.

Many Thanks,

Ben

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LMR23630-Q1: Switching Frequency coupling into the voltage input

September 28, 2018, 7:56 am
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Part Number:LMR23630-Q1

Hello TI,

We are using the LMR23630-Q1 for one of our applications. 

A 10n and 33p Capacitor is used to filter GSM frequencies and above. This filtered 12 V signal is connected to the VIN of the LMR23630-Q1. The two 4.7u capacitors at the input were based on the design suggested by TI Workbench. 

I have found various application notes (1, 2)  from TI regarding designing an input filter to reduce conducted EMI. 

However, where do I begin with designing the EMI filter?

How do the GSM frequency filter caps and VIN input capacitors affect the EMI filter performance? 

Any inputs would be greatly appreciated! Thank you

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BQ35100: Suitable for a 3S x 20P battery pack?

September 28, 2018, 8:14 am
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Part Number:BQ35100

Can I use this as the gauge for a pack of 60 primary lithium batteries configured as 3S x 20P (VT = 10.8V) or 1S x 60P (VT = 3.6V)?

regards

Francis

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UCC28780: UCC28780 power on issue at 0A load

September 28, 2018, 8:57 am
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Part Number:UCC28780

Hi,

I am design a 65W ACF PD design with UCC28780.

I face an issue that:

Test condition: Vin=115Vac/60Hz, Vout=5Vout;

If power on the board with 0.1A load, the output voltage could be built well. And then decrease the output load to 0A, the output voltage could be set at 5V.

But when power on the board  with 0A, the board is alway in re-start state, and the board will be turned off after the output voltage reaches to 5V about 8ms.

I have checked the auxiliary voltage VDD for UCC28780, and it is good before the board was turned off.

Please help provide suggestion.

Br

Eleven Chen

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UCC27714: High side mosfet abnormal turn off when double pulse test

September 28, 2018, 9:08 am
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Part Number:UCC27714

Hi Guys

Our customer are using our UCC27714 to drive a half bridge mosfet in three-phase inverter application.  high side and low side mosfet contain two mosfets in parallel. you can see the Schematic in which I just show U phase. there are V phase and W phase that are the same as U phase.

When customer do the double pulse test. Test circuit is below: which we call it high side mos test.

At this test, we found an issue:  Sometimes, the first pulse is OK, but at the second pulse ON, the high side driver will turn off abnormally. you can see below:

CH1:Vds;    CH2: Ids;     CH3: HO Pin;     CH4: HI Pin;

Zoom In at the event point:

I also asked customer to test the HB pin at the time of event. There are too many pictures. I will post the other pictures at the reply section.

Thanks

-Vincent

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BQ24075: How to continue charging the battery but stop the power to device while usb is plugged in

September 28, 2018, 9:27 am
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Part Number:BQ24075

Hi,

I have to create a fail safe option for my battery powered device where when I plug in the usb to charge the battery the device is not usable (powered down). I Have thought about using a MOSFET on the output pin of this device and use the PGOOD signal to cut off the Vout from going into my system. However, MOSFETs in general fail in short position! Do you have any suggestions? is there standard way of doing this?

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TPS82085: Device Footprint Package Outline Missing From Datasheet

September 28, 2018, 10:28 am
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Part Number:TPS82085

Datasheet for the above part number does not include a pcb footprint package outline. Design Summary outlines uSIP package however datasheet requests uSIP - 8 pin package. I believe this is the same footprint outline as the tps82130 however would like confirmation.

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TPS50601-SP: parts technology

September 28, 2018, 10:48 am
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BOOST-LP5569EVM: Daisy chain LP5569EVM

September 28, 2018, 11:11 am
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Part Number:BOOST-LP5569EVM

We have an application where we are using 4 of the LP5569 IC and 12 RGB LED's.  We would like to test them all.  Is there any way to daisy chain multiple evaluation modules to have them work as one unit?

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TLV758P: Thermal characteristics data plot/conditions.

September 28, 2018, 11:49 am
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Part Number:TLV758P

Hi,

When will the datasheet for TLV758P have the graphs for the thermal dissipation limits?  We would like to know the impact of the copper area pour/number of layers on the thermal limits.

The datasheet TLV758P has had a placeholder image for thermal characteristics since April.

Thank you

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LM5050-2: Choosing correct part

September 28, 2018, 1:22 pm
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Part Number:LM5050-2

Hello, 

I wanted to know if I can use LM5050-2 as a transfer switch in an uninterruptible power supply (UPS). We're using a 120VAC corrected to 12VDC as primary, and we're using a 12VDC car battery as the backup.

Best Regards, 

Carolina 

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LM2596: Regulating 24VAC to 5VDC - 50% Failure Rate - Input voltage gets thrown out to output voltage and destroys low voltage components. 75 Ohms between input and output pin.

September 28, 2018, 3:23 pm
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Part Number:LM2596

Hello, we are using the LM2596SX-5.0 to go from 24VAC to 5VDC. We recently got some circuit boards made and begun testing. We have 50% of our devices fail on initial power up. We are powering these with a 24VAC output transformer. The 24VAC goes through a bridge rectifier, and paired up with some capacitors it creates approximately 30 volts DC (with ripple), which goes into the LM2596.

On the failed devices, I am noticing that the high 30VDC input voltage is being output on the output pin of the LM2596. So basically 30VDC is ending up on the 5V rail and starts smoking other components on the circuit board.

I took an ohm measurement between the input and output pin on a failed board, and I see 75 ohms. (component still installed on PCB).

Here is the schematic and PCB layout centered around the LM2596SX-5.0. This is a low power device... less than 200mA. All of the capacitors are surface mount ceramic capacitors.

I have 2 additional concerns:

1. I probed one of the circuit boards that appeared to be functioning properly, and I noticed that the output voltage from the LM2596SX-5.0 was only 4 volts instead of 5. The circuit still worked because that 4V went into a 3.3V linear voltage regulator... but this is still concerning. I have not verified that every device is like this, but at least 1 of them was.

2. On several of the circuit boards that were working, we disconnected power, then re-connected power. Upon re-connecting the power, the LM2596SX-5.0 immediately smoked and failed. I have no idea what could of caused this since it was previously working just fine?

Thank you for your time, and any help with this is greatly appreciated!

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TPS43060EVM-199: purpose of multiple vias on the input pad of boost inductor L1

September 28, 2018, 4:21 pm
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Part Number:TPS43060EVM-199

Hello,

I am trying to determine the purpose of multiple vias on the input pad of boost inductor L1.  Per layout figures 19, 20, 21, 22 of User's Guide (SLVU828A), these vias appear isolated on all underlying layers.

I would appreciate your comments regarding this.

Best regards,

Nitish Agrawal

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TPS22968: Load Switch On Off Signal

September 28, 2018, 6:53 pm
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Part Number:TPS22968

Hi,

Why is the output still high on Vout when the On/Off signal is low?

Vbias: 5V, Vin1 & 2: 3.3V, On1 & 2: low (0.032V), Vout1 & 2: 3.329V

The On/Off signal is driven low (measured through DMM) through a level shifter TXS0108E.

Thanks,

ALbert

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BQ51013B: how to disable FOD

September 28, 2018, 8:05 pm
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Part Number:BQ51013B

hello：

      I'm hoping to disable FOD in bq51013b，can I just leave Ros open to do this？thanks！

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If the TPS65910A31A1RSL is changed to 5V input, can it be

September 28, 2018, 8:30 pm
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If the power management TPS65910A31A1RSL of the AM335X is changed to 5V input, is there any risk? Currently our application is 3.6V input, I want to change to 5V input.

Or is there any other power management recommendation for 5V input?

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