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BQ24650: STAT1 and STAT2 cycle blink when battery is fully charged

February 11, 2019, 9:05 am
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Part Number:BQ24650

Hi team,

Within our application, the bq24650 blinks periodically STAT1 & 2 with the following cycle steps :

STEP numberSTAT1STAT2Supposed charge state
1ONOFFCharge in progress
2OFFONCharge complete
3ONONFault (?)
4--Go back to step 1

For a better understanding of the situation and the time elapsed between each steps, please take a look at this video

The cycle period is slower when current is lower.

Nominal battery voltage is 12V and lead acid. During  the video, the voltage is around 13.3V so we assuming battery is fully charged.

Our question : Is it a normal situation ? Because we assume when battery charging is completed, charge complete state should be idle and stable.

Regards,

Maxime.

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BQ24630: Can I use the bq24630 for Lithium mixed metal cathode with non-standard charging voltage(?)

February 11, 2019, 9:29 am
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Part Number:BQ24630

Or can someone suggest a better alternative?  I have a 2s design for IS that requires higher than 8.4V charging voltage to account for diodes in the charge path.

With the 24630 I can program a custom charging voltage, and we have used it already for other iron phosphate designs.

Thanks,

Joe Perino

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TPS62152: TPS62152 output voltage with no input voltage

February 11, 2019, 9:41 am
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Part Number:TPS62152

Hello, 

I was wondering what happens, when the output sees a voltage with the input floating or grounded? Would that go beyond the abs max of Vin+0.3? So maxmimum would be 0.3 V at the output with no load connected? 

Thanks!

Mat

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UCC28880: 24V current limiting solution to meet UL Class 2 power limits

February 11, 2019, 10:15 am
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Part Number:UCC28880

I have a 24V output 150W AC/DC feeding two circuits each of which can be limited to well under 96W  and am looking for a  current limiting solution to help me meet UL Class 2 power limits.  Can you recommend anything that has been UL certified to the appropriate standards?  Voltage is 24VDC and current is <= 3.75A.  Thank you

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Overvoltage protection for vehicle electronics

February 11, 2019, 10:48 am
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I am trying to find a solution for overvoltage protection.  The device is going to have the following requirements

  • Operating voltage 32 to 8.5 volts
  • Transient protection ISO 7637-2:2011
  • Maximum steady state voltage 55 volts, device will not be expected to survive voltages above this level.
  • Device max operating amperage 500 mA
  • Protection for 5 volt and 3.3 volt regulators, which have a maximum input voltage of 40 volts.

Does TI offer a low cost solution for the above design?

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LP55231: lp5523(1) charge pump capacitors

February 11, 2019, 11:08 am
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Part Number:LP55231

Hi,

Is it possible to disable charge pump and omit capacitors connected to C1+ C1-, C2+ C2-  and VOUT and connect VOUT to VDD (5 V) for LP5523(1)? I don't need charge pump as there is 5 V voltage present in my device to supply power for leds.

From datasheet I understood that logic levels are defined by EN voltage. Is that correct? I will interface this driver with 3V3 MCU so EN, SCL, SDA will be 3V3 logic levels.

Are all channels of this driver capable of supplying 25.5 mA simultaneously (if adequate cooling is provided - I guess QFN chip should have no problems with cooling when its pad is connected to ground plane)?

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UCD90120A: Power Rails Not Disabling When Faulted; GPOs Not Changing State When Faulted

February 11, 2019, 2:52 pm
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Part Number:UCD90120A

I am using two UCD90120A power monitors on a board. One power monitor controls my standby rails which sequence on initial power up, and the other controls the local rails which sequence when given a command from an FPGA to begin sequencing. I have the PMONs configured such that GPIOs go between the two to indicate when the Standby rails have all reached POWER_GOOD state and when the Local rails have all reached POWER_GOOD state. I use this to control sequencing and desequencing. The Local rails can only sequence when all Standby rails have reached POWER_GOOD. The Standby rails can only desequence when all of the Local rails are no longer POWER_GOOD. Under normal operation this works very well. I discovered recently though that I cannot shut down my Standby rails if they fault. If a Local rail faults, both the standby and local rails shutdown. However, if a Standby rail faults, the fault log indicates a fault and slaves all necessary rails but does not actually disable power on any of the rails. I found that if I remove all signals between the two PMONs, then the fault behavior is normal. So it seems to me that the Standby is waiting for the normal desequence command to begin shutdown in a fault condition. I tried to fix this by using another GPIO to indicate to the Local PMON when a fault occurs on the Standby PMON so that the Local will shutdown and then allow the Standby to shutdown. However, when I set my GPO to go high if there was an overvoltage fault on one of the rails, it would not change states even when I induced the fault on that rail and the logs recorded that fault. I believe it was because the rail was still enabled since it was still waiting on the signal from the other PMON.

I am wondering if there is any way to create this communication both ways between the two PMONs in the case of a fault or to cause the Standby PMON to only wait on the signal from the Local PMON to desequence in normal conditions and not in fault conditions?

Thank you!

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LM5170-Q1: Usage for same input-output voltage

February 11, 2019, 12:29 pm
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Part Number:LM5170-Q1

Hello, my name is Luis.

I am currently searching for a bi-directional converter that allows me to interconnect two groups of batteries of the same voltage (each battery group is 24V). I want to know if LM5170-Q1 will allow me to do this. Also, if it does, how can I regulate the current going from either side? can I implement an embedded controller changing the PWM signal? does this device have voltage or current measurements as well?

Thanks for your help.

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LP8555: What is maxium delta voltage between each string in one port and LED qunatity that can support

February 11, 2019, 4:19 pm
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Part Number:LP8555

Hi

I am using a LP8555 to driver 2 LED bars, LED bar informatin as below picture.

1)String LEDA6 will have longer trace than other 5 strings in port A. So the Vf will be a little higher than others.

   What is the max delta value between the 6 strings in one port that LP8555 can handle? Especially considering LEDA6 Vf caused by longer trace.

2)What's the maxium quantity of LEDs that LP8555 can support?

3)For the thermall, I find form the aplication note that Tj=Ta+（Rθja*power）.Here power means total power of the LED bar or power of each LED string?

Thanks.

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UCD9248: How to let the fusion digital power designer know I have a external instrument amplifer to sense output current of the power module

February 11, 2019, 6:01 pm
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Part Number:UCD9248

I use ucd9248 to control several power modules. The schemetic is as follows. The current sensing is implemented by a independant instrument amplifer measuring the voltage drop at a very small risistor,

We can see from the following picture captured from the fusion digital power designer. It does not know I use independent instrument amplifier. How to let it know my schematic and allow me to choose the parameter of gain of the amplifier?

 

Is it set here? What is the meanning of Iout Cal Gain? Why it uses ohm as its unit? 

My firmware project is also uploaded. Thank you.

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LM5039: About light load operation of the LM5039

February 11, 2019, 6:12 pm
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Part Number:LM5039

Hello

I have a question about LM 5039.

We are currently checking the operation.

When the load becomes low or it gets close to 0 A, there is a function to slow down the frequency and burst.
This LM 5039 thinks that this function does not exist.
Is my opinion correct?

Thank you.

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CSD85302L: Body Diode forward voltage

February 11, 2019, 6:26 pm
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Part Number:CSD85302L

Dear Sir,

May I know what is the forward voltage of the body diode for CSD85302L?

Is TI has any plot for the Body Diode forward voltage like below?

Hope to hear from you soon

Thanks and best regards,

KH

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LM2775-Q1: Allowable operating ambient temperature

February 11, 2019, 6:39 pm
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Part Number:LM2775-Q1

Hi Champs,

 My customer is interested in LM2577-Q1 to supply 5V for TCAN1042 device from 3.3V rail.

System requires Ta=105C, and TCAN1042 consume 180mA at maximum when bus fault.

 While in clause “6.3 Recommended Operating Conditions” Ta is specified as 85C max, is it possible use LM2577-Q1 under Ta=105C condition if its Tj <125C is satisfied?

Best regards,

Nobuo

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BQ40Z80: BQ40Z80 Calibration - CC Gain

February 11, 2019, 6:43 pm
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Part Number:BQ40Z80

 

 

 

 

 

 

How should I go about calculating the floating point value of cc gain outside of the bqstudio. I am using an MIIC-204 iport/usb device to program the bq40z80 chips. I noticed that on other chips an xemics conversion procedure is used to find the 4 byte representation . Is there something like that for the bq40z80.

From the 40z80 calibration sheet,

CC Gain = Icc/(ADCcc-((board offset+cc offset)/cc offset samples))

 

For example

My Icc = -1001mA

ADCcc = -531

Board offset = 0

Cc offset = 0

CC offset samples = 64

Making cc gain = approx.. 1.88512

Does anyone have a method of going from this decimal value to a 4 byte equivalent that I can program it to my 40z80.

 

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LM5122EVM-2PH: LM5122EVM-2PH changes for required specification.

February 11, 2019, 7:54 pm
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Part Number:LM5122EVM-2PH

Hello,

       I am using LM5122EVM-2PH board, for my application Vin- (22-28)Volts, Vout - 36Volts, Iout -7.5 Amps. If possible to make changes to get my Specification ?  if possible, what changes i have to do in that EVM PCB to get my required specifications.

Regards,

Akshay H B

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TPS54620: Sequential Startup of Multiple TPS54520: PWRGD connected to following EN, but PWRGD doesn't go HIGH.

February 11, 2019, 7:58 pm
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Part Number:TPS54620

Hi,

I have multiple TPS54620 that I am aiming to power-on sequentially using the technique illustrated in the part manual (reproduced below):

I have connected the PWRGD pin of one of my TPS54620 to the EN pin of the next TPS54620. I have NOT used an external pull-up resistor.

The converter is functioning properly and producing the correct voltage with minimal ripple (NO choppiness). In addition, I checked that the VSENSE pin and measured it to be 0.799V which means it is within 94% to 106% of VREF. So I can't seem to understand why PWRGD isn't going High by itself. The only thing I notice that is unusual is that the inductors are whistling but I'm not sure if that's relevant since the output voltage is correct and stable. Please let me know if you have any insights or further suggestions to try.

Thank you,

Kevin

P.S. I realize there's another forum post about PWRGD and EN pin for sequential start-up, but that forum post has 2 TI employees who provide contradictory answers. One says that no pull-up resistor is necessary, and the other suggests to use a pull-up resistor. Since I've already fabricated my PCB without a pull-up resistor like the manual suggested, I'd like to find a solution that doesn't require me to use a pull-up resistor.

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TPS55340: TPS55340 EVM(TPS55340EVM-017) VIN noise

February 11, 2019, 8:11 pm
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Part Number:TPS55340

Hi,

Could you please why EVM board which VIN pin have noise (Due to our customer board also have this kind of noise)

Warm Regards,

Lin

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BQ24707: Setting the output charge regulation voltage is not as expected

February 11, 2019, 8:51 pm
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Part Number:BQ24707

Hello guys,

I can communicate through SMBUS: ChargeCurrent() = 1A. write ChargerVoltage() = ~8.4V, with power supply set to 20V, but the BAT voltage is still 20V.

I want to decrease the BAT voltage to 8.4V.

I wish someone could help me to try to find the problem.

Thanks!

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TPS62081: Exceeding 2mA in snooze mode

February 11, 2019, 9:00 pm
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Part Number:TPS62081

In normal usage, we do not exceed 2mA in snooze mode, as recommended in datasheet's Recommended Operating conditions.

However, in production stage, before MCU firmware programming stage, we will exceed this condition for close a minute or so.

Under this scenario, while in snooze mode and load current exceeds 2mA:

1. What is the maximum rating without damaging TPS62081?

2. What is the efficiency above 2mA? (Figure 4 of datasheet stops at 2mA). We don't need characterized data, but just indicative data.

2. What is the quiescent current when load exceeds 2mA? (Just need indicative. Safe to say <30uA?)

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REF200: Modern SMT REF200 Replacement or Alternative

February 11, 2019, 9:02 pm
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Part Number:REF200

Hello,

Working on a tiny design and am looking for a replacement or alternative to the venerable REF200 which is only available in the "huge" SOIC package. Needing both a current source and a current sink, (2) separate, very small devices could be feasible.

Thanks,

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