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TPS65400: I have output current and Voltage fluctuation issue when i plug SOM (RPI compute module 3)

April 24, 2019, 4:37 am
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Part Number:TPS65400

Hi,

I have used TPS65400 in my design. It works well till yet as per voltage conversion. Sw1: 4.1V, SW2: 3.3V, SW3: 1.8V and SW4: 2.5V.

When I plug SOM(RPI compute module 3) then the o/p voltages get disturbed and not continuous like 4.1V varies from 1.5V to 2.5V  and also other peripheral not getting operating voltages as well.

Now Problem is that 1. As i have checked(Without plugging SOM) with digital potentiometer(load) at value of 3 ohm@4.1V , I got 40mA(max. 60mA) output current while I need above 1.2A. Now what to do ??

I have also used reference circuit as per EVM , webench and other TI reference.

Please find the attached Schematic and Give your suggestions/approvals as soon as possible as it is very critical stage for us.

Thanks

Irfan

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TPS65400: Power management forum

April 24, 2019, 4:37 am
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Part Number:TPS65400

Hi,

I have used TPS65400 in my design. It works well till yet as per voltage conversion. Sw1: 4.1V, SW2: 3.3V, SW3: 1.8V and SW4: 2.5V.

When I plug SOM(RPI compute module 3) then the o/p voltages get disturbed and not continuous like 4.1V varies from 1.5V to 2.5V  and also other peripheral not getting operating voltages as well.

Now Problem is that 1. As i have checked(Without plugging SOM(Please visit the site to view this file)) with digital potentiometer(load) at value of 3 ohm@4.1V , I got 40mA(max. 60mA) output current while I need above 1.2A. Now what to do ??

I have also used reference circuit as per EVM , webench and other TI reference.

Please find the attached Schematic and Give your suggestions/approvals as soon as possible as it is very critical stage for us.

Thanks

Irfan

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TPS92691-Q1: TPS92691-Q1

April 24, 2019, 4:45 am
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Part Number:TPS92691-Q1

Hello,

Can you please tell me what is the leakage current at Vin pin?

I mean what if I apply a constant 12 V at V_in and make V_PWM=0 V?

In my application,Vin is powered from battery directly.

Thanks in advance for your support.

Regards,

Abhishek

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TPS40210: TPS40210DGQR phase margin

April 24, 2019, 4:47 am
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Part Number:TPS40210

Hi all,

I have done a step-up with a TPS40210DGQR: Vin is 24V nom, and Vout is 52V, 0,75A nom (attached image).


I must to change dinamically the output voltage, from about 44V to 63V. To do this I would like to change R1 in order to increase or decrease the vout.


My issue regards the phase margin.. If I change the R1 value, It could be that I must to change the compensation network too, in order to keep the correct phase margin.. But I can't change dinamically the compensation network..


I tried to change the value of R1 into the webench Power Designer, then I done some simulations and trace the bode diagrams. My target is: any changing of R1 cause a permissible phase margin change. In the proofs that I have done the phase margin is always the same.. How it's possible?


The principal value of R1 are:

  • 750ohm for 44V, about 100W;
  • 634ohm for 52V about 100W;
  • 520ohm for 63V about 100W.

With these value, I have some dangerous configuration?
How can I verify these situations?

Thanks in advance, best regards,
Diego.

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LM723: LM723 OUTPUT VOLTAGE

April 24, 2019, 4:54 am
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Part Number:LM723

I have a few questions on the datasheet. (1) On the table where it has all of the equations. Is the output voltage the regulated output or is the ouput coming from the serries pass transistor (pin 6 on the metal can package)? Also on Fig 18. (my schecamic is similar but not exact), the following are the differences: R1: 18.214K, R2: 8.71K, Vref is a NC, N.I ( pin 3) pin has 6.2 Volts, IN (pin 1) pin has a power supply of 1.4 volts connected to the bottom of R2 (where the GND is on the Fig. 18), RSC is 0 .7 ohm resistance. Between pins 6 and 10 there is a 500 ohm resitance, with a BJT (2N4150) where the collector is connected to VCC, V+, the base is connected to pin 6 and the emitter is connected to pin 10. Along with 2k to GND on pin 6. V- is connected to GND. Now my other question would be the difference when there is 14 volts vs 21 volts applied to VCC, V+ and the colllector of the bjt. I think this will change the the regulated output but I am unsure how much this will change

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TPS7A84: a model for tina

April 24, 2019, 5:00 am
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Part Number:TPS7A84

Hi!

Can you tell, please, is there the TINA model for the TPS7A84? Looks like the two models provided on the TPS7A84 web page are not applicable for TINA.

Regards, Vic.

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LM5176: LM5176 as a supercap charger

April 24, 2019, 5:25 am
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Part Number:LM5176

Dear All,

In our new project we are using LM5176 as a supercap charger. Main specifications are;

Vin=18V~36V

Vout=45V

Iout=1A

Cout=1.32mF created by 60x 22uF@1.2R Al-El caps.

Fs=400Khz

L=100uH with 18mR DCR

During prototype work we could not boost Vout to 45V even without supercapacitor load. While trying to get in work, we rearranged FB point to Vout=5V and strangely we saw that Bottom FET of Boost leg is ON with ~5% percent duty.

what woould be the reason, which poiny(s) should i check?

Could you pls help us?

Thanks in advance.

(Please visit the site to view this file)

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Buck and boost IC

April 24, 2019, 6:02 am
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Dear All Have a nice Day

I am new to this forum

I am working with TPS63060  buck boot converter

it input voltage is 2.5 to 12v and output is 2.5v to 8 v But I need 

input 2.5v to 15v and output voltage 2.5 to 15v converter 

usage 

Line follower robot with two DC motor

DC motor 

6v 300rpm ( N20 Type)

I am planing to run robot at constant voltage even battery voltage drooped 4v 

Please advice

Dayan

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TPS51200: V-vosns specificaition

April 24, 2019, 6:30 am
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Part Number:TPS51200

Vvosns spec is split into two rows.  Can values be combined into one row.  Example:  Row 1 , TYP -= 1.25V.   Row 2 -15mV MIN and +15mV max

Can we subtract / add MIN and MAX values to the TYP value to determine range for VOSNS output voltage and tolerance?

i.e.  for VREFOUT = 1.25V, Vvosns MIN = 1.235V, TYP = 1.25V, MAX = 1.265V?  and so on for the other voltages?

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BQ34110: Battery charging inhibition when temperature too high not working

April 24, 2019, 6:31 am
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Part Number:BQ34110

Hello,

For our application with a Lead Acid battery (float voltage = 13.65V, 6 cells, capacity = 38Ah), we need to stop charging the battery when the temperature is higher than 45°C.

For this, I've considered §2.9 of http://www.ti.com/lit/ug/sluubf7a/sluubf7a.pdf , JEITA bit is 0, WHr charging is not enabled, NIMH_CHG_EN bit is 0, Ni_DT bit is 0 and Ni_DV is 0. So I expect ChargingVoltage() and ChargingCurrent() equal to 0 when temperature > JEITA T4 Temp = 450. Reading §2.9.1, I've also set Charge Inhibit Temp High = 450.

While charging the battery, I let the temperature be approximately 51°C and I observe the different measurements. The fact is that I have well as expected ChargingVoltage() = ChargingCurrent() = 0, however, Current() doesn't change and I still have a charging current of approximately 3 A.

I don't understand how can I stop the battery charge when a defined temperature is reached, this is observed Current() no more positive.

Is there something I'm missing in the datasheet ? The fact that I observe ChargingCurrent()=0 seems to show that I'm in the correct configuration but I don't understand why Current() is still positive.

I join a copy of the data flash as a txt file.

Thanks in advance,

Axel

(Please visit the site to view this file)

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BQ34Z950: Battery Capacity at Full Charge.

April 24, 2019, 6:50 am
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Part Number:BQ34Z950

I am using BQ34z950 for my Lion battery pack (4 cell in series). The design capacity is not correct it shows 7809mA. I have the design for 40AH. How can I set this. Here is my GG file (Please visit the site to view this file).  I looked some other post related to this and found some steps for charging/discharging to set Qmax. What are the steps for BQ34z950? Few More questions.

1) What should I write in Design voltage (battery nominal voltage(14.4V) or battery full charge voltage(16.8V))?

2) In EVSW it shows that maximum capacity can be 32676. Is there any way to increase this?

Please Help!.

Regards,

Aman.

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LMZM33606: Fsw and capacitor values in normal and inverting applications?

April 24, 2019, 6:51 am
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Part Number:LMZM33606

Hello,


I'm planning to use LMZM3360x series power modules in both Buck  and IBB configurations. Hence i need a psu without noise and ripple, i will use LDOs after them. Here is general info,

19V Input  =>  LMZM33606, +12.6V, 4.4A out
19V Input  =>  LMZM33606, -12,6V 3.2A out
19V Input  =>  LMZM33602, +5,6V 1,1A out

Here are my questions,

1) I know suggested max operation frequency is 1.2MHz and datasheet says above this, effiency will drop. But how much drop there is gonna be? I want to increase Fsw to 2MHz cause LDOs' PSRR values are not good at 1MHz ( around 15dB).

Webench does not allow me to do it but when i change Rt value, i can get 2MHz. Does this effect other components' values? Can i get these amount of current with 2MHz switching frequency? 

2) I've checked a few designs in TI forum and Webench values for input and output capacitors are lower than these designs. For example, in evaluation board there are 39uF Alu + 2x 4.7uF ceramic input caps  and 4x 47uF + 150uF Tantalum output caps. But when i try to use Webench, it suggests using 2x10uF input caps (de-rated 8,6uF) and 4x22uF output caps ( de-rated 56uF).

These values are vastly different from evaluation board. Should i add Aluminum or Tantalum caps at the input and output? Also maybe increaseing ceramic caps values?  What should be my caps values in total for this applications? 

Thank you in advance.

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TLC6946: Technical reference manual

April 24, 2019, 6:55 am
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Part Number:TLC6946

Dear community members,

I'm looking for TLC694x 16-channel LED driver technical reference manual that written on TLC6946/48 datasheet like below picture.

Please share it with me, if you have or know that document.

Regards,

Jeffrey

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TPS65632: The Risk of Reverse Current to ELVDD

April 24, 2019, 7:00 am
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Part Number:TPS65632

Hi, 

Customer is using TPS65632 in their AMOLED panel, and find that there is a 90mA reverse current to ELVDD pin, if there is a risk of it?

Best Regards.

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BQ2057W: Dual batteries with dual thermistors. How do we incorporate them into the one input on the device?

April 24, 2019, 7:01 am
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Part Number:BQ2057W

Hi, we are looking to use the BQ2057W with a two li polymer batteries, max voltage 7.4 volts, but they both have there own thermistor in each battery.

The problem is that the BQ2057 only has one input for thermistor monitoring and we need to combine these two into this one input.

Do you have any advice on how we can combine the thermistors into the device, or perhaps you may have an alternative device that can accommodate the two thermistors in this way.

We have two separate batteries physically set apart from each other and that's why they have separate thermistors.

Thanks

Ian White

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TPS51206: Open short test data of TPS51206

April 24, 2019, 7:02 am
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Part Number:TPS51206

Hi

My customer require the open-shot test results of TPS51206.
Could I get thier data or technical review about them?

Best regards,
Yokota
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UCC28019: UCC28019 No load audio noise issue

April 24, 2019, 7:02 am
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Part Number:UCC28019

Under the condition that the input voltage is higher than 150Vac and the load is no load, the PSU will emit an abnormal sound.

RD test report is attached,How can I modify this phenomenon?Thanks.

(Please visit the site to view this file)

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BQ24170: Charging time and TTC setting

April 24, 2019, 7:08 am
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Part Number:BQ24170

Hi 

We set the TTC as below 

tTTC= CTTC x KTTC = 0.1uF x 5.6 min/nF = 9.3hr

However when charging a 2 cell battery from 6.42V to 8.36V it only take 4.5 hours. 

Our schematics attached below. 

May i ask what will impact the charging time ?  thanks!

(Please visit the site to view this file)

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BQ4050: NTC B factor

April 24, 2019, 7:13 am
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Part Number:BQ4050

In BQ4050 datsheet, NTC recommendation is a Mitsubishi BN35-3H103 with a B factor value of 3486K.

My cell pack is equiped with a  Semitec 103AT-4 10K Ohm NTC with a B factor value of 3435K.

Is there an issue on the B value delta ?

Regards

Gilles

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LM5067: LM5067's UVLO/OVLO resistor selections other question

April 24, 2019, 7:49 am
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Part Number:LM5067

Hi Experts,

My customer has properly selected resistors based on calculations in datasheet. Below is threshold they have chosen. The reason they choose UVL lower than operation voltage, or OVL higher than ads rating is customer does not want LM5067 to protect during UV and OV scenarios. In other words, they do not want UVLO and OVLO, and it is because LM5067 must have R1-R3 so it can normally operate so they have to select resisors. 

Except what has been noted in datasheet for value of resistance calculating, is there any other specs we should take care when choosing specific resistor? Like size, Power dissipation or voltage abs rating.

Thank you!

-Wenhao

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