Quantcast
Channel: Power management forum - Recent Threads
Viewing all 35901 articles
Browse latest View live
↧

TPS92513HV: Short pulse high voltage

February 20, 2019, 7:21 am
$
0
0

Part Number:TPS92513HV

Hi,

For a new design I want to create a strobe light with IR LEDs (Osram SFH 4249 - UV). These LEDs will be preferably connected with 15 in serie, what would result in a Vf of 35-45 V.

I would like to use the Iadj pin to reduce the current and use the PDIM pin to start the flash. These flashes will be a maximum of 0.3 ms and a minimum of 0.1 ms, with a switching frequency of 1 - 100 Hz.

My question since this will be powered by a capacitor bank and a small power supply I wonder if the headroom is not to small because I want to power it with a 48 V power supply. 

↧
Search

TPS793: TPS793

February 20, 2019, 7:31 am
$
0
0

Part Number:TPS793

Hi

I'm trying to use this regulator to drive the DVDD of a WM8741 DAC to 3.3V.

IN and EN pins are at 5V (from a computer USB), OUT pin has one a ferrite bead in series and one 47uF electrolytic to GND,

NR pin has one 0.01uF ceramic cap to GND.

At first start, everything is fine, output voltage is 3.3V, current 60mA.

After a short time, 20 seconds, voltage drops to 2.5V, device start to smoke, temperature is about 35°C,

current still 50-60mA and, of course the output of the DAC has a lot of distortion.

I have to shut down the power before the regulator dies.

I can't find out what is wrong.
Any help would be welcomed.

↧
↧

TPS61040EVM-002: Output current setup queries

February 20, 2019, 7:35 am
$
0
0

Part Number:TPS61040EVM-002

Hello

I am planning to use TPS61040 in my design. There are a few doubts.

Need to drive 4 IR LEDs in series(VSMY1850X01) with forward current of 100mA.

The system is powered by a Li-ion Cell. 

These LEDs have a forward voltage of 1.65V.

How to calculate resistors R1, R2, R3 and R4?

I need PWM to control the intensity also. The minimum average current of 50mA and Max Average current of 100mA. Do these minimum and maximum values affect Resistor Values?

What is the purpose of D6? is it some kind of protection? Can this be omitted from BOM?

This is the Link to LED datasheet: www.vishay.com/.../vsmy1850.pdf

↧

TPS63060: Buck mode current sinking capabilities

February 20, 2019, 8:27 am
$
0
0

Part Number:TPS63060

Hello,

I am trying to build a TEC driver similar to this Application Report: www.ti.com/lit/an/slva677/slva677.pdf

My input voltage is in the range of 8V to 12V, so I can not use the same converter as in the report. Instead I built it with the TPS63060 as I thought they would behave alike.

In boost mode everything works fine, current output up to 200mA -- more is not necessary and not tested.

Buck mode on the other hand does not work. TEC current has a maximum of around 30mA, feedback voltage diverges from the 0.5V reference. Setting the output voltage without load works. After double checking everything I do now think that the problem might originate in TPS63060 current limiting or something similar that prevents operating as current sink in buck mode.

Is my assumption, that the TPS63060 is not capable of sinking current in buck mode, correct? If so, what other part can you recommend for the job?

Thank you!

↧

LM5146-Q1-EVM12V: Are the Altium Design files available for this demo board?

February 20, 2019, 8:38 am
$
0
0

Part Number:LM5146-Q1-EVM12V

Hello, are the Altium design files (Schematic, PCB layout, gerbers, etc) available for this demo board?

thanks

↧
↧

TPS92692-Q1: IMON state consult

February 20, 2019, 8:46 am
$
0
0

Part Number:TPS92692-Q1

Hi team,  my customer want to know the voltage of IMON pin if our device in fail state (not switching)?I believe this will be zero, right? Also if we connect SS or PWM to GND, how about the voltage of IMON? Thanks.

↧

LM5112: Fast mos driver (LM5112) + fast mos (suggestion?) for a pulsed led driver

February 20, 2019, 9:09 am
$
0
0

Part Number:LM5112

Dear All,

i need to pulsed an uv-led with a frequency from 100kHz ( 5 us on, 5 us off) to 1 MHz ( 500ns on 500ns off) with few ns of rise/fall time. I'm thinking to use a fast mos driver like the lm5112 (or if you know something better) plus a fast switching mosfet. The led had a working point between the 6-7V and the current will be between 5 and 30 mA.

Did you have any suggestion about the mosfet to use and if there is something betther than the lm5112 for my purpose? (Maybe the lmg1020, but i never used GaN mos).

Actually i'm simulating my circuit with Tina.

Thanks in advance.

↧

BQ24133: BQ24133: How to increase battery charging current

February 20, 2019, 9:27 am
$
0
0

Part Number:BQ24133

We have made battery sharing circuit /PCB using BQ24133. it  primary functionality looks ok. The Li-on battery is getting charged . But it takes 8-9 hours for full charge. it is consuming  only 300mA.. Can anyone help me how to increase the battery charging current ( our expected charging time for full charge is 3-4 hrs). 

the measured values are

voltage at ACSET pin is 0.807V

ISET voltage is 0.404V

As per design,

Input ACSET voltage is 2A

I charge  is 1 A

Thanks in advance for your reply.

↧
Search

TPS25942A: Temperature Questions

February 20, 2019, 9:33 am
$
0
0

Part Number:TPS25942A

Hello,

I’m hoping you can help provide some additional specifications (or clarification) for the TPS25942 over temperature.

Here’s some things I’m hoping to clarify (there may be more later):

  1. The I(FASTRIP) specification:  States 1.5 x I(LIM) + 0.375.  This has notes (1) and (2).  Note (2) indicates that thermal effects must be taken into account separately.  What does this mean?  What is the tolerance of I(FASTRIP) over temperature?
  1. I looked at the tolerance of I(LIM) and realized that it was basically +/-8% for the current limit resistors given in the datasheet.  Can I assume these same tolerances on the fast-trip limit since the fast-trip equation refers to I(LIM), or is the tolerance wider for the fast-trip?
  • The Ron range is listed as 26mohm to 64mohm from -40C to 125C.  Is this positive temperature coefficient (higher temp, results in higher resistance)?

Regards,

David

↧
↧

TPS62748: Buck not switching from PFM to PWM mode

February 20, 2019, 10:06 am
$
0
0

Part Number:TPS62748

Hi,

I am using the TPS62748 as a power supply in one of my designs. I am using an MCU that draws 4 mA so starting the MCU is no problem. However, from time to time I activate another component in the design which is also connected to the buck converter. This component momentarily consumes 70mA. I then see that the buck converter can't switch from PFM to PWM mode, so this component never starts.

Obviously I have done something wrong.

The output capacitor of the buck is 10uF (same as input capacitor). Total load capacitance on buck (including output capacitor): 18.7uF. I don't have a good estimation of the PCB capacitance. I have used the following inductor:

1285AS-H-2R2M=P2 from Murata.

Could you please tell me where to find more information about what parameters affects the switching from PFM to PWM mode so that I get a starting point when searching for the root cause in my design?

Thank you!

↧

TPS3700-Q1: Data sheet top view and mechanical data does not agree with each other

February 20, 2019, 11:02 am
↧

LM5175: UVLO schematic check

February 20, 2019, 11:18 am
$
0
0

Part Number:LM5175

Hi Guys,

My customer is changing the EN/UVLO settings away from from 3.3V (10K) pullup to

VBAT and a divider of 205K and 47.5K.

 

Do you see any issues/concerns  with these values?

math is on the sheet below.

Really concerned with the value for crank (below).

Does this fall into line or do I need a higher value?

Thanks,

Brian

↧

TLV700XX-Q1: Question about symmetric power supply regulation

February 20, 2019, 11:29 am
$
0
0

Part Number:TLV700XX-Q1

Hi, I'm sorry to be the one asking the "would this work..." question, but I prefer to ask before buying! So, my question is the following:

If I had one 3.7V Li-ion battery and I needed a symmetric supply for a 3.3V EMG application, could I use a TLV70033-Q1 to regulate it from 3.7V to 3.3V operating at 50mA? By reading the datasheet it seems that it'd work. I'm more confused about the negative part. The negative suuply is working at around 10mA, as it's not supplying the digital circuitry, just the analog, thus I thought about using the TPS60403 60mA Charge Pump Voltage Inverter to get -3.7V, and then use a negative LDO to get -3.3V? (I couldn't find a fixed 3.3V negative voltage regulator that's like the TLV70033-Q1, which would you recommend?)

Would you recommend this setup for EMG applications in which the signals are very susceptible to noise? Maybe the Charge Pump adds too much noise and it's better to get two 3.7 batteries and connect them in series to get the symmetric supply? I hope you understand my questions!

Thanks in advance!

Roberto

↧
↧

TPS22990: TPS22990: Is there a maximum CT(pF)/output rise time spec?

February 20, 2019, 12:46 pm
$
0
0

Part Number:TPS22990

TPS22990: Is there a maximum CT(pF)/output rise time spec?

I have followed the old threads but my question is not answered.

I am using TPS22990 as a Voltage Switch.

VIN = 5 V

VBIAS = 5V

ON = 5V 

All 5V are applied at the same time. Is this acceptable ? or do I need to sequence these ? VIN, VBIAS and then assert ON ?

I see a Vout T Rise of 1 ms under these conditions:

Ct = 0.47 uF

Cin = 1.0 uF

Cout at device = 0.1 uf

Cload is ~ 200 uF

I am expecting a T Rise on the VOUT of ~ 15 ms, but see 1 ms T rise

I added more Ct and still 1 ms.

Can this switch give me a T rise of 15 ms ? under these Voltage and load conditions ?

Thanks !!!

↧

TPS22990: TPS22990: Is there a maximum CT(pF)/output rise time spec?

February 20, 2019, 12:55 pm
$
0
0

Part Number:TPS22990

My setup :

TPS22990

VIN 5V

VBIAS 5V

ON connected to VIN 5V

Ct of 0.47 uF

CIN 1.0 uF

COUT 0.1 uF

Cload ~ 300 uF

T rise is measured at 1 ms, I expect at least 15 ms. Is the switch capable of 15 ms T rise under these voltage and load conditions ?

Thanks

↧
Search

TPS22990: TPS22990: Is there a maximum CT(pF)/output rise time spec based on VIN VBIAS Cload and Iout ?

February 20, 2019, 1:00 pm
$
0
0

Part Number:TPS22990

VIN 5V

VBIAS 5V

ON is connected to VIN 5V

Ct = 0.47 uF ( is this too much C ? )

I am measuring VOUT T Rise of 1 ms and expect 15 ms or more.

Cload is 300 uF 

I load is 100 mA

Do I need to sequence the ON pin ?

Thanks !

↧

LM27761: When first enabled output goes positive before going negative

February 20, 2019, 1:25 pm
$
0
0

Part Number:LM27761

I have an LM27761 being used to generate -1.7V. It's enabled by a +3.3V signal. 

When enabled I'm seeing the output rise to 380 mV within the span of about 400 us 

before going low.

Is this normal?

↧
↧

LM73606-Q1: Feedback pin connection after sense resistor

February 20, 2019, 2:15 pm
$
0
0

Part Number:LM73606-Q1

Hello,

 

Is there any reason to not connect the feedback pin of a LM73606-Q1 after a sense resistor (used for current sensing) to compensate for the voltage drop?

I assume that it is fine since it is equivalent to having a higher inductor resistance there will not be any issues.

 

Thank you

↧

LM5116-HT: is there a CPGA-20 package?

February 20, 2019, 2:17 pm
$
0
0

Part Number:LM5116-HT

Hi guys,

Customer is looking for a buck with no thermal shutdown for a drilling application.

There is a confusing comment in both the LM5116-HT and LM5116WG datasheets. First, the -HT datasheet has lots of mention of thermal shutdown but later specifies the thermal shutdown is actually disabled for the ceramic DIP package. I am correct in assuming there shouldn't have really been any mention of thermal shutdown at all because the -HT ONLY comes in the ceramic package, right?

Second, the WG datasheet mentions a CPGA-20 that has no thermal shutdown. That is incorrect, right? The only ceramic package this part comes in is the CDIP-18, which is the -HT, right?

Finally, can this part be purchased in die?

Email me offline if this should not be discussed on E2E.

Thanks!

Brian 

↧

LM5034: Dual interleaved regulator

February 20, 2019, 3:49 pm
$
0
0

Part Number:LM5034

Working principal of LM5034 dual interleaved regulator. (With sample circuitry)

Thanks in advance.

↧
Viewing all 35901 articles
Browse latest View live
Search
<script src="https://jsc.adskeeper.com/r/s/rssing.com.1596347.js" async> </script>