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bq78350

August 26, 2019, 10:01 am
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Hello, everyone.

I have ten cells battery based on BQ78350 with BQ76930

So, all parameters are set good and values(like a current, capacity, voltage cells, TS1, TS2 , charge etc...) obtained correctly.

But first cell every three or five minutes get wrong value - 34 mV (should be between 3300mV and 4200mV).

What could it be?

Best regards, Derrick

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BQ25150: What happens when BQ25150 is turned on the first time fresh from TI (not programmed)

August 26, 2019, 10:14 am
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Part Number: BQ25150

Hi!

I would like to know what the BQ25150 exactly does when it get's turned on. Because my goal is, that the BQ25150 powers my Host (TI cc2642), that then programs the BQ25150 via i2c every time after power up.

I really hope this is possible, what would you say? The TI cc2642 needs a minimum of 1.8V to operate.

What pin gives what voltage when powered by a 4V LiPo battery the first time (not programmed)?

If this is not possible, can you please recommend me another charger and fuel gauge IC?

Thanks!

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UC1825A: UC1825A

August 26, 2019, 11:42 am
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Part Number: UC1825A

Hi,

Question regarding the Clock signal on Pin 4. We use this clock signal to trigger another external circuit. The loading current is about 3.7mA. UC1825A spec has maximum current of 5mA. Is there any issue if we are loading at 3.7mA especially over temperature performance ? 

Also, there is a plateau voltage about 0.7V after the pulse turn off. Is this plateau voltage could increase or decrease ?

Best Regards,

Jason

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LM5176: Bootstrap issue, MOSFET selection.

August 26, 2019, 11:47 am
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Part Number: LM5176

I made some strange experience with a new design using LM5176PWPR but today I see a behavior I can't explain myself. First of all, I control the output conditions of the DCDC converter with an external (low speed) regulation loop at the SS pin. As an example, it can provide a changeable CC/CV characteristics controlled by a microcontroller. It’s a 55V/500W output design. Input is 48V.

The system is working in buck mode. The HS MOSFET of the boost side is constantly active. In the past I noticed, that the bootstrap circuit switched the boost half bridge one time at a gate voltage of about 3.5V to bootstrap the drive circuit. This behavior us not working today. I see no switching, BUT the gate voltage is constantly on at about 7V. Yesterday I notice the same behavior on the buck MOSFET. Is there an internal circuit that provides power for the bootstrap path? I don’t think so, but the voltage is also available and without ripple using an additional “bleeding resistor” at the gate?

The next thing I can’t explain is, that if the same system switches to boost more (constantly voltage instead of constantly current), the gate of the HS MOSFET stops switching. There is no gate-source voltage and the MOSFET works as a simple Diode. Is there a reason the HS-MOSFET is not switching? Are there safety features I don’t know?

Last but not least, I have some troubles finding the right MOSFETs. I need 80V types to have a good margin but most of them have a threshold voltage higher than the minimum high-side gate voltage of 3.5V. I found one with a minimum of 1.1V but with this MOSFET I have to add a bjt gate discharge circuit. Without it, I see a high shoot-trough current (hiccup triggers as well when active). The 80V TI MOSFETs have a threshold that is critical with the actual bootstrap circuit (3.5V min.)

 

Regards,

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BQ25505: Does a TI TINA model for the BQ25505 exist that one can have a application schematic in TINA

August 26, 2019, 12:11 pm
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Part Number: BQ25505

Hello

 trying to see if one can TI TINA SPICE the BQ25505 in a simulation -- could that be made available?

thanks

Jim Mrowca

(former TIer 1982-1997)

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CSD17573Q5B: CSD17573Q5B

August 26, 2019, 12:28 pm
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Part Number: CSD17573Q5B

Hi,

I am trying to use pspice model of this part CSD17573Q5B. But when I run the simulation I am getting an Unknown parameter error:

**** RESUMING testfets.cir ****
.END
---------------------$
ERROR(ORPSIM-16015): Unknown parameter.

Please help to correct this problem

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TPS63051: Can the mode pin be changed on the fly

August 26, 2019, 12:41 pm
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Part Number: TPS63051

Hi Support team

Just need to confirm - Can I dynamically switch the mode pin, so for example, the customer wants forced PWM during normal operation due to noise issues, but when in USB suspend mode they need it to be in PFM mode. 

thanks

Jeff

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TPS56C215: Product came back from the field with a malfunctioning module

August 26, 2019, 12:42 pm
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Part Number: TPS56C215

Dear Team-

I received the product from the field and after analyzing the power management system, I found out that the TPS56C215 failed. Upon power on, I could hear buzzing noise. After I desoldered the IC and soldered a new one, the module started operating normally. The IC did not look fried or damaged. 

I would like to know if there are any known reasons for why the chip would fail in such a way.

The input to the module is 12V from TI LMR14050SQDDAQ1. The output is 5V with 10A max load and typical operating current of 0.5A. The product is deployed outdoors in a waterproof enclosure. It has been running for about 7 months until it failed. Other products with identical hardware have been deployed in similar conditions and have not failed. 

I would like to know what happened number one, and number two if there is a way to prevent such failure from happening in the future. 

The schematic is attached.

Best,

Rob

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TPS23880: PoE Architecture Question

August 26, 2019, 1:20 pm
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Part Number: TPS23880

I am implementing a POE solution using a TPS23880 PSE. I am using 2 of the ports to implement a 90W PD connection. I also have four 15.6W PD in other parts of the board. I am having issues putting together a power supply that outputs 56V @ 3A that does not use a heatsink, so I split the power supplies into one for the 90W and one for the four 15W (62W or so). The problem I am now seeing is that the VPWR line probably wants the power that is being sent to the Ethernet connector and I have 2 powers. Is it best to then set up two separate PSE devices or can the 8-port one be used for both even though the VPWR would only be connected to one of the supplies? I have a feeling I know the answer, but had to ask.

Thanks,

Brian

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BQ40Z80: Manual Protection FET Control

August 26, 2019, 1:30 pm
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Part Number: BQ40Z80

Hi team,

Is there a simple way to manually control the bq40z80 protection FETs similar to the HostFETControl() on the bq78350? Or would it require using FET_EN + the FET toggles? I see the MFC feature as well but it seems to be for emergency shutdown only if I understand correctly.

Thanks,

Antonio

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TPS61230A: Input equals output voltage and current input increases after 10 seconds

August 26, 2019, 1:31 pm
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Part Number: TPS61230A

Problem:

  • The TPS61230 will not boost the input voltage.  3.5V @ 50mA limit is input from power supply.  Output is also 3.5V.  So, it appears that the input equals the output, but it was verified that there is no continuity between Vin and Vout prior to energization of the power supply.
  • Voltage stays steady at 3.5V on the output for about 10 seconds.  After that, the power supply shows current increasing from about 10mA all the way up to the limit of 50mA.
  • I noticed on the datasheet for the TPS61230A that there is an error in the table on pg 13.  R1 and R2 should be switched in this table, assuming 316kOhm should really be RFBT.

Design:

  • Webench design that I followed:

    • There are slight deviations from the BOM that was recommended from Webench:
      • ESR of caps and inductor are not exact matches but are within 20%
      • Cout is tantalum instead of ceramic
  • PCB Layout:

Test Setup:

  • Oscilloscope and Power Supply connections:
    • There are two vias on the polygon that is the input to the TPS61230A.  One of these vias goes to the enable pin of the TPS61230A.  The other via goes to the RPGD resistor of the unplaced BQ25606 (the QFN to the left).  The other end of these resistors are not connected to anything.
    • CO2 and CO3 are output capacitors for the BQ25606.  Their values are 10uF each.
    • The oscilloscope probe is on the Vout, attached to a vertical header pin.  There is also an orange cable that leaves from this pin.  It has a 10kOhm power resistor connected to it and then to ground.  This is to provide some load to the TPS61230A output.
  • Oscilloscope output with power supply at 5V and 50mA limit:
    • This scope shot shows the voltage after 10 seconds of the power supply being turned on.  The sags in voltage are due to the power supply nearing the current limit of 50mA.  After the second sage in voltage, the power supply was turned off, and that is why the scope shows the voltage returning to 0V. This test was repeated 3 times, with the same type of input and output behavior.  The current limit was increased to 150mA on the last try.  The current increased again after 10 seconds, this time all the way to 150mA.
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LM74700-Q1: reverse polarity protection + load switch + bidirectional current

August 26, 2019, 3:53 pm
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Part Number: LM74700-Q1

Hello support,

I am designing a power path for high current 20A~30A and wide input voltage 10v ~ 40v

The application requirements call for

1. Reverse polarity protection

2. Load switching

3. Inrush, OVP/UVLO and Transient protection

4. Bi-directional current control

There is a dual charging input with source selection and no current sharing ...

I could use either #LM74700 or #LM5050 I suppose to ORing the chargers. But I will need a back-to-back FETs for source selection.

Now, since the charge path has a relatively low current rating (2A max), I was planning to use PFET with some discrete transistor logic to allow charging / disable PFET for reverse current protection when two chargers are plugged in. The downside is adds design / debug complexity 

One possible scheme I am considering is depicted in the diagram below. However, according to the datasheet, the LM74700 also block reverse current so I am not 100% if this will work.

Alternatively, I could bypass #LM74700 and feed SPEIC output to BAT_IN (PWR_EN = LOW). In this case, Q4 (with some logic) acts as reverse polarity protection in the event the battery inputs are reversed. 

Another scheme is to use a single #LM5060 and drive the NFETs. However, it must be be enabled (PWR_EN = HI) to allow charging while the system is OFF,  however this means higher quiescent current and battery drainage....

Again, I could bypass #LM5060 and feed SPEIC output to BAT_IN (PWR_EN = LOW). In this case, Q4 (with some logic) acts as reverse polarity protection in the event the battery inputs are reversed. This looks like the most cost effective option but requires small signal diode Or NFET from LM5060 GND pin to GND. Do you see a problem with this approach?

Q1) Can you please confirm if the LM74700 can be used with bidirectional current applications?

Q2) The charger input are 12v~24v do you have a suitable solution that meet the above requirements?

thank you!

Alex.

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LM36922H: Schottky Diode Recommendation

August 26, 2019, 5:22 pm
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Part Number: LM36922H

Hi, Team,

My customer plans to use the RB161QS-40T18R for the LM36922HYFFR. Could you please check the attached spec? I think there is no problem, but I want to double check.　

Best Regards,
Satoshi Yone

(Please visit the site to view this file)

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LM5145: SYNCOUT Specification

August 26, 2019, 5:41 pm
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Part Number: LM5145

Dear, Sir.

My customer is utilizing SYNCOUT function on LM5145. They are asking the

specification of it at this time.

1. SYNCOUT Output Volatge.

a)The datasheet is defined min. 3V, but real voltage  is not clear.

   Please let me know how to calculate maximum SYNCOUT volatge.

b)If above voltage is depended on the source/sink current, Please clarify the

  correlation chart SYNCOUT volatge & Source/sink current.

2. SYNCOUT Duty.

a)Please clarify the min. & max duty of SYNCOUT signal.

Please give your advice.

Best Regards,

H. Sakai

  

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TPS54302: TPS54302 Question phenomenon in which output voltage rises at no load?

August 26, 2019, 6:59 pm
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Part Number: TPS54302

Dear support member,

My customer used TPS54302EVM-716.


(Situation)
I have confirmed the operation with the evaluation board of TPS54302.


If nothing is connected to the load, the output voltage gradually rises.

When an electronic load is connected to the no load, the above phenomenon does not occur and the output voltage stabilizes.


(Question)
Q1
What is the cause of the gradual increase in output voltage?

Q2
What should be corrected in the circuit to output the output voltage stably when not connected?


I attached schematic and waveform.
Could you check it?

(Please visit the site to view this file)

Best regard.
Bob Lee.

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we need a LED Driver for 1.8V/0.75A LED.

August 26, 2019, 7:03 pm
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hello

we need a LED Driver for 1.8V/0.75A LED which is used in automotive DMS product.  could you help provide suitable device? 

Thanks a lot!

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we need a power switch IC with -12V/0.5A

August 26, 2019, 7:12 pm
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hello

we need a power switch IC with -12V/0.5A wich can be controlled on/off by high/low level input.

Could you help provide suitable solution?

Thanks a lot!

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Buck controller with 100% maximum duty cycle

August 26, 2019, 7:20 pm
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I need a buck solution with 100% maximum duty cycle. Output of my application is 5V with 13A max. load and ~8A continuous load at 85 ℃ ambient temperature. Is there any buck controller with 100% maximum duty cycle?

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UCC27211A-Q1: Can the HS Bootstrap drives two FETs?

August 26, 2019, 7:27 pm
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Part Number: UCC27211A-Q1

hi Sir/Miss,

Is it possible to drive two similar HS FETs with Bootstrap?

Gate charge is now 2 times.

Is the calculation below correct?

Gate capacitance, C = (Gate charge x 2) / (VDD - Vboot diode)

Bootstrap capacitance > 10 x Gate capacitance ?

Please correct me if I am wrong.

Thanks.

Wilson

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TLC59284: PWM Dimming Usage

August 26, 2019, 7:40 pm
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Part Number: TLC59284

Dear, Sir.

I found the PWM dimming usage for LP5018 on TIDA-050011.

It is utilizing IREF pin.

I wonder similalr usage will be possible for TLC59284?

Please give your advice.

Best Regards,

H. Sakai

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