As I am trying to complete the learning process of supercapacitor but learn cycle fail. A scope does indicate that the capacitor voltage doesn't actually reach V learn Max. It reaches to 11654mV and starts discharging.

I have updated my initial, design value of supercapacitor and the value of ESR in the data flash screen. SBS screen showing me the exact value of capacitor and ESR. BQEVSW does not calculate the value of the capacitor and ESR.

I want to know what should I do to complete the learning process so the bqEVSW calculate the exact value of capacitor and ESR?

Thank You,

Grishma

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BQ33100: Supercapacitor learning process

February 20, 2019, 4:23 am

≫ Next: LM43601: Start up problem with inverting application SNVA722B

≪ Previous: BQ33100EVM-001: Supercapacitor learning process

Part Number:BQ33100

Hi,

I am using bq33100EVM-001 for balancing and monitoring the value of supercapacitor and its ESR measurement.

I want to know what should I do to complete the learning process so the bqEVSW calculate the exact value of capacitor and ESR?

Thank You,

Grishma

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LM43601: Start up problem with inverting application SNVA722B

February 20, 2019, 4:23 am

≫ Next: TPS2373: APD

≪ Previous: BQ33100: Supercapacitor learning process

Part Number:LM43601

Dear all

I used LM43601 in our application and had very serious issues with unreliable start up. The device locks up to a positive voltage of approximately 0.5V.

My conclusion is that it has something to do with the BIAS pin. If I connect the BIAS pin to device ground (which is the negative output rail of the circuit in this case) the circuit seems to work reliably. It tested with different loads through a temperature range of 0°C to 100°C and it always powers up properly and can deliver currents much higher than needed for our application.

Is this an error on the application note or something that I have overlooked in the design? Is the circuit reliable with the BIAS pin connected to device ground? I have attached the actual circuit from our application with the component values I used.

(Please visit the site to view this file)

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TPS2373: APD

February 20, 2019, 4:51 am

≫ Next: alternative to STSNS01PUR

≪ Previous: LM43601: Start up problem with inverting application SNVA722B

Part Number:TPS2373

Dear Team,

Can you help on double check the APD pin design is correct or not?

Besides, if APD pin is higher than 1.65V, the hot swap MOSFET will turn off directly, right?

The customer mentioned higher APD voltage will have lower VDD voltage here.

Can you help on confirming it?

Kevin

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alternative to STSNS01PUR

February 20, 2019, 4:54 am

≫ Next: TPS25944A: Suspicious behavior, probably reverse current related

≪ Previous: TPS2373: APD

hi all,

I'm looking for alternative to the STM charger.

The BQ25150 is the closest i might find, hope you can prove me wrong.

I need ultra low Iq in shelf/ship mode, integrated 3-3.3V LDO, fix 4.1 or 4.2 Vbat, 80mA charging current from USB

thanks a lot in advance

Vincenzo

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TPS25944A: Suspicious behavior, probably reverse current related

February 20, 2019, 5:17 am

≫ Next: BQ24133: Schematic review

≪ Previous: alternative to STSNS01PUR

Part Number:TPS25944A

Hello,

I'm using the TPS25944A as an eFuse according to the attached schematic. The circuit needs quite a lot of capacitors because of other schematic aspects.

What I observe is that the nFLT output never gets high and the output is switched on and off with a frequency of about 100Hz if there is a low resistive load (<100mA). Increasing the load leads to an increased frequency of the nFLT pulses and out ripple. If the load is around 1A everything gets fine and the nFLT is constantly high.

My only guess for this behavior is that the reverse current comparator is triggered by a current flowing from the output capacitors to the input capacitor. I would not have expected this and unfortunately this generates a lot of noise. There is no possibility that current is fed from outside. Current can only come from the capacitors. The capacitors are low ESR types (<20mR).

PGOOD is OK all the time.

Is there a way to prevent this toggling for low loads/currents?
Are there other reasons that might cause this behavior?

I would appreciate any help...

Thanks and regards,
Reno

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BQ24133: Schematic review

February 20, 2019, 5:20 am

≫ Next: Recommendation for gate driver

≪ Previous: TPS25944A: Suspicious behavior, probably reverse current related

Part Number:BQ24133

ist it possibel to get a Schematic review

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Recommendation for gate driver

February 20, 2019, 5:32 am

≫ Next: UCC2808A-1Q1: UCC2808A-1Q1 usage problem

≪ Previous: BQ24133: Schematic review

Hi,

I am designing a phase shifted full bridge dc-dc converter.

Input voltage: 400VDC

Output voltage: 650VDC

Power: 3500W

I need recommendations for gate driver that can be used to drive 600V MOSFETs for this dc dc converter. The PWM signals come from Max10 FPGA. Please include recommendations from non-isolated (bootstrap type) and isolated gate driver families.
It would be great if design recommendations for phase shifted converter with the above ratings can also be provided.

Thanks,

Lakshmi

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UCC2808A-1Q1: UCC2808A-1Q1 usage problem

February 20, 2019, 5:48 am

≫ Next: WEBENCH® Tools/TPS23753A: Please check the schematic diagram of TPS23753A,thanks a lot;

≪ Previous: Recommendation for gate driver

Part Number:UCC2808A-1Q1

My design is open loop (OUTA and OUTB duty cycle is constant 50%), the starting current peak value is small (soft start time 1ms and above), the current soft start time can only be 400us, how can we improve the soft start time?

Can you help me see the schematic diagram?

The cs pin is connected to the resistor, which will cause the power supply efficiency to decrease and some troubles later. Does the CS pin need no resistance?

thank you！

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WEBENCH® Tools/TPS23753A: Please check the schematic diagram of TPS23753A,thanks a lot;

February 20, 2019, 6:02 am

≫ Next: Via in Pad of LMG1020...

≪ Previous: UCC2808A-1Q1: UCC2808A-1Q1 usage problem

Part Number:TPS23753A

Tool/software: WEBENCH® Design Tools

↧

Via in Pad of LMG1020...

February 20, 2019, 6:02 am

≫ Next: TPS53319: We want to double check whether the device can accept 10uF for the VREG of TPS53319

≪ Previous: WEBENCH® Tools/TPS23753A: Please check the schematic diagram of TPS23753A,thanks a lot;

Part Number:LMG1020

I want to connect inverting input pin and GND pin of lmg1020 to internal ground plane through VIA ON PAD itself...

Is it safe to do that(As LMG1020 has BGA packaging)...?

If it's safe then please suggest VIA parameters for the same...

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TPS53319: We want to double check whether the device can accept 10uF for the VREG of TPS53319

February 20, 2019, 6:58 am

≫ Next: LM5145: Solution for multiple high power +24V outputs

≪ Previous: Via in Pad of LMG1020...

Part Number:TPS53319

Hi team,

We want to double check whether the device can accept 10uF for the VREG（normally the datasheet use 1uf), thanks.

↧

LM5145: Solution for multiple high power +24V outputs

February 20, 2019, 7:02 am

≫ Next: UCC27211: HO stays low after a N channel mosfet is connected

≪ Previous: TPS53319: We want to double check whether the device can accept 10uF for the VREG of TPS53319

Part Number:LM5145

For a new project for a customer we want to make a design where we need 3* +24V/15A and 1* +24V /6A out of incoming 230Vac per unit (each machine will contain 42 of these units).

Therefore we are thinking of a Vicor unregulated 1750W converter (BCM6123TD1E5135T00) to create +40Vdc out of +320V dc (=rectified 230Vac in) and using 4* LM5145 to create max +24V/15A max at each output. This is purely based on very worst conditions where we think in practice this will never occur but in theory we have to take account with it. It may also be another converter but I think the LM5145 looks the best solution for us at this moment (also wrt costs)

I already did a simulation with the LM5145 set at +24V output and this showes that the impact of a voltage change at the input has not much effect on the output voltage voltage which is important for us.

Still some questions when using this solution:

1) Do you think this solution will work? Of course the input voltage can vary because the converter is a non regulated version (1:8) so each input change (e.g. ripple) will be visible at the output of the Vicor but it looks the LM5145 could handle over a wide input voltage range and simulation shows not miuch impact at a voltage change from +30V to +50V at the +24V output.

2) The Excel calc sheet shows 350uF cap at the output with an extreme low ESR of a few mOhm. The very best cap I can find is already 13mOhm. Or is it OK when we put a ceramic cap parallel with the big cap at the output to reduce ESR? Or has the ESR much impact on the output ripple? The Excel sheet shows 35* 10uF cap in parallel (I think for the low ESR) but this looks not very practical for the final design...At your eval board I see a lot of 47uF ceramic caps in parallel with the output elco but I guess these will be not cheap for higher voltages (+35V or higher)

3) Are there some special precautions required with a load of 15A at +24V? The Excel sheet shows a power loss of 4W for the upper MOSFET at 15A load. With a thermal resistance of 50C/W this would result in 200C temp rise. We have a 32 degrees coldplate for the converter so maybe we can find out if we can manage to connect the FET to the coldplate? Or are there MOSFETs with lower thermal resistance with similar specs so the temp rise will be less? The dissipation in the coil and lower MOSFET is lower according the datasheet so probably not a problem..

4) We need 4 of these converters at one PCB all connected to the same output of the high power 1750W converter. My idea is to sync one converter with the neighbour to use shifter clock and maybe running the third one at a different clock speed and sync this one to the fourth so we have 4 converters running at different clock edges and frequencies to minimize interference and EMI. We have to deal with EMI Standard class A (we prefer class B when possible)

5) T.I. has an evaluation board with the LM5145 but with +5V output. Do you think we could use this for +24V (out of +40V in) and by changing some component values modify it for +24V output? The inductor (3.3uH) and MOSFETs look the same as I get as suggested values from the Excel calculation sheet at +24V output. So when we could change this by only changing some resistors it would be nice.

6) At your EVAL board I see a large Schottky diode in parallel with the bottom FET. However in webench designer and in the Excel sheet schematics I don't see this diode. Is it required for the design or is there a special reason that it is not shown at the Excel sheet?

I hope you can help us with these questions so we can continue with investigating the final solution

Best regards

Chris van der Aar

Sr Hardware Engineer

NTS Systems Development

Eindhoven, The Netherlands

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UCC27211: HO stays low after a N channel mosfet is connected

February 20, 2019, 7:08 am

≫ Next: TPS54620: What is the output inductance current waveform of TPS54620 overcurrent protection? We measured that overcurrent protection did not work.

≪ Previous: LM5145: Solution for multiple high power +24V outputs

Part Number:UCC27211

Hi for everyone who is reading this,

For a project I am experimenting with the UCC27211 high and low side mosfet driver. I want to make a "power" amplifier using the stated driver in combination with a n channel trench mosfet (SQP90142E). But it seems that I can't get the driver working properly. As a reference I used the "UCC27211 transient analysis" that is available for Tina-TI (see picture below). I adjusted the capacitor load (CloadHO & CloadLO) with a rough estimation of the N channel mosfet I intend to going to use.After building the circuit I measured with a scope the HO and LO outputs. The graph is in my opinion correct (minus the huge transients on the flanks, but that is probably due to that I use a bread board (A)).

Only when I connect the N channel mosfets gates to the LO and HO output (without connecting to mosfet any further) the HO output goes to 0 and will not recover anymore even when it is not connected anymore. And when I try to build the circuit stated in the datasheet, using the circuit with only one UCC27211. The mosfets will conduct straight away doesnt matter what timing the HI and/or LI has.

Does someone already experienced this or knows a solution, I will be very glad to hear it.

Kind regards,

Remco

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