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TPS24720: MOSFET selection

September 20, 2018, 9:20 pm
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Part Number:TPS24720

Hi,

I'm looking to use the TPS24720 in for a 12V hot swap circuit that i want to current limit at 20A. I know the demo board for this part uses 2x CSD16401Q5A FETs to provide a 12V, 25A circuit. My questions is if i can use a single CSD16415Q5 FET for my 12V, 20A design with a load capacitance of 1800uF. I looked at the demo board for the TPS24772 design which is a 100A circuit and it uses 4 of the CSD16415Q5 FET, so i think a single one of these FETs should be able to handle 20A that is in my design. I also downloaded the TPS24720 design calculator spreadsheet and ran the numbers for the CSD16415Q5 FET with my design parameters of 12V, 20A, 1800uF and it looks ok. I just want to be sure that i will not operate the CSD16415Q5 FET outside it's SOA and thus breaking it.

Thanks

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TPS92691: Buck Boost LED drive voltage & current ripple

September 20, 2018, 9:43 pm
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Part Number:TPS92691

Hi 

We are using TPS92691 for LED back light driver of LCD display for below spec:

Input spec: 8-36V. Currenlty we are testing with 12V input

Output spec: 12.8V, 180mA

Observation: Output current & voltages are coming as desired but Mosfet switching stop for approx 1msec in every 3ms This cause approx 2V drop in output voltage.

Please tell is this desired behavior. 

I have attached waveforms for more clarification.

Channel 3: Mosfet Drain voltage w.r.t GND

Channel 1: V_Ris

Channel 3: VLED+ w.r.t GND

Channel 1: V_Ris

regards

Vinod Sharma

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LM5032: LM5032

September 20, 2018, 9:59 pm
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Part Number:LM5032

Hello Sir

I want to design an interleaved (two switches in parallel) boost converter having specifications as follows :

Input voltage : 210-310 Vdc

Output Voltage : 400 Vdc fixed

Iout max :5A

I had looked at LM5032 but there are no specifications mentioned anywhere .

Can I use LM5032 for my application ? or else Please suggest the other solution which suits for my design specifications.

Thanks 

Regards

Rajashekar

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BQ24640: MOSFET Selection

September 20, 2018, 10:40 pm
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Part Number:BQ24640

Condition:

Device: BQ24640

VIN: 12V

VOUT: 2.7V

Icharge: 1A

 We used the FDD3642 to do the charge function with bq24640 for super cap application. However, the charge current is limited to few mA. after checked the Id vs. Vgs characteristics. it looks the Vgs=4V doesn't work with this device since it doesn't be fully turn- on.

We tried to use the bq24640EVM's MOSFET (SiR426DP) on customer system board, it's ok for charger function of 1A. However, we also tried to use similar part of SiR426 as FDD8447L. it doesn't work with charger. From the Id vs. Vgs characteristics it looks ok.I don't why? and what critical parameters of MOSFET could also improve this problem? how to choice the MOSFET correctly? Very thanks.

FDD8447L


 

 

  SiR426DP


 

FDD3642


 

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Soft-start time of LM317A

September 20, 2018, 10:44 pm
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We have question about LM317AT/NOPB.

Please tell us the time from voltage input to voltage output(Soft-start time).

Vin=24V

Vout=3.3V

Iout :min :16.5mA

       type：18.6mA
      max ：19.8mA 

best regards,

Takahiro Nishizawa

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BQ24105: I need Ni-MH Charger.

September 20, 2018, 10:46 pm
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BQ40Z50-R2: FCC update at the end of discharge

September 20, 2018, 11:22 pm
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Part Number:BQ40Z50-R2

Hi,

I am observing in our system log files the FCC of the battery pack is updating to very less value (like from 19Ah to 10 AH) at the end of discharging, and recovering back at the end of charging. I am not understanding what parameter causing this. I am attaching the gg.csv file with this. Please help us in finding the root cause.

Thanking you,(Please visit the site to view this file)

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BQ24610: A question about the device operation flow chart？

September 21, 2018, 12:05 am
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Part Number:BQ24610

Dear Sir

        when che charge go into the constant voltage mode ,in the next chart why turn off the charge?

        thanks&regards

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LM3481: Queries in application note of LM3481

September 21, 2018, 12:10 am
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Part Number:LM3481

We are referring LM3481 application note for designing Non-Isolated Fly-back converter. For that we are going through the design formulas given in application note.

In the application note of LM3481, there is one equation to calculate Primary Inductance Lm in page 5, and a graph is given to choose the primary inductance value with respect to Vin in page 10. We tried to calculate primary inductance  with equation in page 5 which is not matching with the graph. Example specifications are given in page 9 , with these specifications the calculated primary inductance is not matching with graph or selected Lm=12uH

Please let us know how the graph has been achieved for the range of input voltage specifications given in section 4 (page 9) of application note.

We are trying to design Fly-back converter with below specifications

Vin(min)=3.16V

Vin(max)=25.66V

Vout=12V

Iout=1.556A

Fsw=100KHz

Turns ratio=1

(Please visit the site to view this file)(Please visit the site to view this file)

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BQSTUDIO: BQSTUDIO

September 21, 2018, 12:29 am
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Part Number:BQSTUDIO

Hi team

*Store the setting

I need to select registers to record log of watch at every time at  lunching  the bqStudio.

If I could store these setting to some file. I could skip these .

Does bqStudio have a function to store the my setting ?

 

 

*Dash board of % of bqStudio

Is this % “True State of Charge” ?

best regards K.Kanao

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BQ24650: Layout questions - GND pin, Thermal Pad

September 21, 2018, 12:30 am
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Part Number:BQ24650

Team,

our customer would need help with bq24650 layout:

"I have question about Battery Charger bg24650.

I design new PCB with bq24650 and I'm trying to do the best layout.
I read recommendations in technical documents SLUSA75A (datasheet) and SLUU444A (user's guide).
One of recommendation is "Route analog ground separately from power ground and use a single ground connection to tie charger power ground to charger analog ground.". That I understand. But I have problem with assignment pins GND(11) and ThermalPad to analog or power ground.

In datasheet SLUSA75A page 4 is write:
11 - GND - Power ground. Ground connection for high-current power converter node. On PCB layout, connect directly to source of low-side power MOSFET, to ground connection of input and output capacitors of the charger. Only connect to GND through the thermal pad underneath the IC.

Recommendation page 28 (SLUSA75A):
Route analog ground separately from power ground and use a single ground connection to tie charger power ground to charger analog ground. Just beneath the IC use analog ground copper pour but avoid power pins to reduce inductive and capacitive noise coupling. Connect analog ground to the GND pin. Use the thermal pad as a single ground connection point to connect analog ground and power ground together, or use a 0-Ω resistor to tie analog ground to power ground (thermal pad should tie to analog ground in this case). A starconnection under the thermal pad is highly recommended.

Page 22, figure 15 (SLUSA75A):
On the schematic is GND pin connect to power ground.

User's guide (SLUU444A) page 17, figure 8:
On the schematic is GND pin connect to power ground.

User's guide (SLUU444A) page 11 - 14, figure 2 - 5:
On board layout is GND pin connect to analog ground. Thermal Pad is connect to power ground.

  • My question is, where should I connect GND pin and where Thermal Pad? What's the best? Is Board layout of EVM the most important recommendation?

Thank you for your help,
Kind regards,
Customer

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BQ27426: BQ27426

September 21, 2018, 12:37 am
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Part Number:BQ27426

HI

* Data flash

Does bq24726 have a function to store the battery profile that are measured by Dallas ?

If it is, does these stored in OTP or Ram memory ?

If it is , which manual should we read for operation.

 

 

State of Health

Is this parameter to know the battery aging. ?

How to define（QMAX and Ra） ? ex 50% is half of capacity from new one. ?

best regards K.Kanao

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TPS3420: The two inputs are low while the output is still high

September 21, 2018, 12:52 am
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Part Number:TPS3420

Hello,

I've observed a strange behavior on my design.

The TPS3420 is used as shown below :

When the two inputs are low, sometimes it works and output becomes low, and sometimes output remains high.

Do you have any suggestion to explain this behavior please? Is it in relation with the current in the inputs?

Thank you

Best regards

Alex

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TPS61194: Behavior when V_IN > V_OUT

September 21, 2018, 12:52 am
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Part Number:TPS61194

Hello,

This question applies to TPS61193 / TPS61194, configured as Boost converters.

Circuit example #1:

Output voltage is maximum 26.62V (3.66V*7 white LEDs in series per each string + 1V for current sinks in normal operation).

Input voltage range is between 6V and 28V.

Circuit example #2:

Output voltage is maximum 11.98V (3.66V*3 white LEDs in series per each string + 1V for current sinks in normal operation).

Input voltage range is between 6V and 35V.

In both examples, the input voltage can be greater than the output voltage. In such case, I have a few questions:

What happens when V_IN > V_OUT?

It is obvious that the output voltage will follow the input voltage, but is the LED string current affected?

Is any FAULT condition triggered? If yes, which are those and in which cases these FAULT conditions can appear?

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TPS40040: TPS40040 inquire output spec 40A/2.8v

September 21, 2018, 1:02 am
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Part Number:TPS40040

Dear,

our want design

Vin:3.8V

Vout:2.8V

Iout:40A

TPS40040 it`s could be change MOSFET and inductor can meet output spec 40A/2.8V

If any suggestion, Please advise me.

Thanks,

Best regards,

Lawrence.

 

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CCS/UCD3138A: FAULTMUX counter does not work properly

September 20, 2018, 11:39 pm
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Part Number:UCD3138A

Tool/software: Code Composer Studio

Hi，

I'm using fault mux module to realize protection function to shut off DPWM. however,  I need protection works after a few DPWM periods. so I set a AB_MAX_COUNT. In UCD3138 Digital Power Peripherals Programmer's Manual, it says "Each fault has its own 5 bit counter, with a maximum value set by a dedicated x_MAX_COUNT bit-field. The fault lines are monitored continuously, but only one event per DPWM period is counted. If the x_MAX_COUNT value is set to 0, the first fault event will shut off the appropriate DPWM pins.The maximum number of sequential fault periods is 31,  if the x_MAX_COUNT field is loaded with a 0x1f. The faults must occur sequentially. If any period completes without a fault, the counter will be reset". However, it seems do not work properly. Even the fault event shorter than the MAX_COUNT, it will shut off the DPWM. It seems that the Counter does not reset, and the delay time is not equal the set MAX_COUNT time.

can you please help to answer why it does not work. thanks.

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UCD3138: PMP8877 and UCD3138

September 21, 2018, 1:25 am
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Part Number:UCD3138

Please provide design files for the PMP887 1/8 brick.

Do you also have calculations/simulations for the planar magnetic coils built into the design.

Thank you.

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Compiler/UCD3138: UCD3138

September 21, 2018, 1:34 am
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Part Number:UCD3138

Tool/software: TI C/C++ Compiler

Hi：

I want to ask some quentions about UCD3138 DPWM master-slave mode.

Suppose LLC topology. I configure DPWM0(Primary mos) as master, and DPWM1(SR mos) as slave.

then i will write code like this:

"

Dpwm0Regs.DPWMCTRL0.bit.MSYNC_SLAVE_EN =0;
LoopMuxRegs.DPWMMUX.bit.DPWM0_SYNC_SEL = 0;

Dpwm1Regs.DPWMCTRL0.bit.MSYNC_SLAVE_EN =1;

LoopMuxRegs.DPWMMUX.bit.DPWM1_SYNC_SEL = 0;

"

and I suppose DPWM0 's deadtime is the same as DPWM1's deadtime, for example: DPWM0's deadtime is 350ns , DPWM1‘s deadtime is 350ns

and filter0  is connect to both dpwm0 and dpwm1.

Do DPWM1 follow DPWM0 no matter what circumstances?

if both EVENT1 is same .   They will always open together ,but dpwm1 will close earlier than dpwm0 or the same time as dpwm0 (According to the resonance frequency), Do I understand correctly?

Is there any situation that is not open at the same time（Even the phase will stagger.）? 

many thanks！

Zoe

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LM74670-Q1: Vgs signal abnormal

September 21, 2018, 1:50 am
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Part Number:LM74670-Q1

Hi,

customer use LM74670-Q1 as full bridge rectifier, but they found the Vgs is abnormal and has noise on Vin. 

customer use 1uF as charge pump capacitor and use CSD18563Q5 as transistors. the waveform as below show.

could you help on this?

Vin is 24VAC, below is Vin wavform:

 

the Vgs waveform as below:

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TPS22953: Vout drop issue of TPS22953?

September 21, 2018, 1:59 am
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Part Number:TPS22953

Dear Sir:

               We follow datasheet page 32 , Figure 63. to design our circuit as below picture, We have a issue as when U4 IN1 turn off and Vout have drop as below picture 2 , Does TI have suggest to us? such as increase output capacitance?

CH1=>+3.8V

CH2=>+VBAT

CH3=>SW1_PG

CH4=>SW2_EN

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