Power Modules - Forum - Recent Threads

choosing power modules

ARUNA KUMAR — Thu, 28 Feb 2013 09:21:13 GMT

have a single230 to 12V adapter. I need to generate 5V/1a 3.3V/3A, 1.0V/30A, 2.5V/9A ,1.8V/9A & 1.2V/4A Where should I start?

i am planing convert 12V to 5V and den V to 2.5v,1.8v,1v

12V TO 3.3V den 3.3V to 1.2V

Minimum input capacitance for multi-module design

D. Johnson — Mon, 02 May 2011 20:41:52 GMT

I have a design that has 3 power modules, PTH05050W and PTH04000W (x2). These are feed by a common 5V main supply.

PTH05050W - 5Vin, 3.3Vout, 3.0A max, step load 0.5A max

PTH04000W - 5Vin, 2.5V out, 1.0Amax, step load 0.30A max

PTH04000W - 5Vin, 1.2out, 1.5A max, step load 0.30A max

The data sheets call for input capacitor of 100uF, 47uF and 47uF minimum respectively. It is desirable to keep capacitance to a minimum for size and inrush reasons. According to appnote SLTA055, it seems that I "could" use less capacitance and meet my requirements.

http://focus.ti.com/analog/docs/litabsmultiplefilelist.tsp?literatureNumber=slta055&docCategoryId=1&familyId=561

Question - Can I safely use something less for input capacitors ? Concerns if I use less.

I currently have a 33uF tantulum and 10uF ceramic on each and everything seems OK. I just need to clarify if this is or is not OK.

There are 4 cap pads per input (two large, two small) that can be used for other caps if you have a better recommendation.

Paralell module co-existance, PTH08T240W

TIguru — Tue, 14 May 2013 21:31:33 GMT

Hi,

I am using PTH08T240W in parallel with another TI module (PTH05T210W ) but I only want one or the other to drive voltage into my 1.0V rail. We are using the inhibit pin in PTH08T240W to turn off its output while using the second module. We are getting brownouts on the output voltage. My question for you is can the two modules co-exist if one of the two is being inhibited? or will the output of the inhibited module present a load that will cause the second to misbehave?

Please advise. Your help will be greatly appreciated.

Regards,

TPS84A20 exposed thermal pad dimensions and location not described in datasheet

Franz Rottner — Wed, 15 May 2013 09:18:57 GMT

For CAD library, I need urgently information for TPS84A20 dimensions and location of the exposed thermal pad.

This information is not given in the datasheet

How does Rtt value affect the output of PTH modules?

rainer03 — Sun, 05 May 2013 21:13:37 GMT

Rtt values can be either calculated or found in the selection table, while most of them are not standard values. Is it necessary to use multiple resistors to get the exact value or just pick one close to this value?

Btw, does Rtt have any requirement on power rating? I didn't find such information in pth datasheets.

PTB78560x question

Ken Hasselmann — Tue, 30 Apr 2013 21:56:31 GMT

Hi,

I'm currently designing a PCB for a robotics application, but when i did send the prototype to printing,
i forgot that i had a 10.8V battery.

I saw after that the PTB78560x (http://www.ti.com/lit/ds/symlink/ptb78560a.pdf), does only allow Vmin to be 18V.

M question is : Can I use the PTB78560AAH to get 5VDC from a 10.8VDC battery ?

Thanks,
Regards.

PTN78060 Failure

Timothy Cann — Tue, 09 Apr 2013 22:58:15 GMT

We've installed hundreds of these without a single failure. Then last week we had one go. What surprised me was that rather than no voltage on the output, after the failure the voltage on the output pins was the input voltage! Not good, No voltage I can live with but putting the input voltage on all of the downstream components made it a nightmare. I've been through the spec sheets and I see no options to control this. Can you suggest how we protect against this kind of event?

Tim

Reliability Report for PTH05000W and PTH04T220W

Danny Cheng — Mon, 22 Apr 2013 09:24:02 GMT

Hi, I would like to request for the reliability and qualification report for PTH05000W and PTH04T220W power modules.

Also, can I check on what is the IPC classification for both modules?

Thank you.

Regards,

Danny

PTH08T230WAD Not Working

Suresh Samynathan1 — Fri, 12 Apr 2013 07:58:33 GMT

Hi,

We are using PTH08T230WAD for 4.0V generation. The module was working fine for 3 weeks. After that the module is not starting up.

When we probed the Inductor point and Mosfet gate signal in the module, found no switching happing. When the power is first applied, the module is not giving any PWM. It is always low.

We removed the INH/UVLO resistor and still the module is not starting up.

I have atatched the schematics for reference. Please clarify why the module is not starting up.

Multiple PTH08T2xx modules w/ & w/o SmartSync

rainer03 — Thu, 11 Apr 2013 18:15:59 GMT

I'm using several PTH08T2xx modules in my design, which include one PTH08T210 that doesn't have SmartSync. Does it still benefit if I enable SmartSync on other modules (PTH08T220/PTH08T230)? In the datasheet of PTH08T210, I see such a mixed design (Fig.24) where SmartSync is not activated on PTH08T220. Any suggestions on this?

Can I use two resistors in series for Rset for PTH08T2xx modules?

rainer03 — Thu, 11 Apr 2013 04:50:33 GMT

I can't the resistors with desired value for Rset. Can I use two resistors in series instead?

TPS84250 AGND pin 37

Uzi Ben-Zion — Sun, 07 Apr 2013 16:40:04 GMT

Hi,

Recommended footprint shows eight Vias around pin 37 (AGND). However, the recommended layout doesn't use these Vias as they are connected only to AGND plan on the Top layer and are isolated from the PGND layer. This way it does fulfill the demand of connecting the AGND and PGND on a single point on pins 8 and 9. The question is why the so called eight Thermal Vias are needed?

May I connect AGND to pin 9 and PGND to pin 8 and use the internal connection, between pins 8 and 9, without connecting them externally?

Thanks,

Uzi

Can two TPS84210RKG chips operate synchronously?

Sergey Avdjushin — Thu, 28 Mar 2013 07:24:44 GMT

Hello!
I am going to use the TPS84210 chips for C6424 DSP powering.
1.2V for core and 1.8V for DDR memory.
The chip have RT/CLK pin for external clock.
I do not understand what I can use as a clock source.
I thought about the PH PIN, but the documentation is clearly written: "Phase switch node. These pins should be connected by a small copper island under the device for thermal PH relief. Do not connect any external component to this pin or tie it to a pin of another function."
Can these two chips operate synchronously?
Serg.

TPS84610EVM-003 / can be supplied 6A output current by EVM ?

Ryuji Asaka — Thu, 28 Mar 2013 08:27:51 GMT

Hello,

In User's guide of TPS84610EVM-003, there is 4A rated output current in P.2 and there is 0.8V to 3.3V @ 4A in P.6.

Can be supplied 6A output current by this EVM ?

Since TPS84610 is integrated inductor and can output 6A current , so I think that I can use this EVM by 6A without problem.

But could you please kindly give me the confirmation?

Best Regards,

Ryuji Asaka.

SENSE+/- lines

guy lemire — Fri, 29 Mar 2013 21:25:14 GMT

Hello,

i wanted some clarification on the placement of the sense+/- lines.

I am using a PTH04T230 and the data sheet indicates the sense+ is to be placed near the load and the sense- is to be placed within 10 cm of the part. What is the reason for placing the sense- close to the module? All i can think of is for common ground designs (which i am doing), you get a mixture of currents on the GND plane which can cause insatbility in the switcher.

Regards,

Guy

requirement of dc-dc converter for rly application

umashanker kalyanam — Sun, 31 Mar 2013 04:23:03 GMT

Input Voltage		36/40vdc -140vdc (dynamically varying).however max voltge is for 2mts only for the purpose of testing . otherwise usual range shall be bet 36-74vdc (varying)
2	Output Voltage/Wattage		74VDC,300Ma (constant)

3	POT for Output Voltage Adjustment		not required
4	Mounting Arrangement		DC/DC Board Mount-thru hole
5	Dimensions		LOW profile
6	Any Other Special Features Required		1. Output over voltage protection 2.Negative/Possitive logic

Requirement:2

Output capacitor selection for PTH modules

Chandana Bhat — Wed, 27 Mar 2013 05:29:07 GMT

Hello,

I wanted to confirm the output capacitor selection for pth08t250w, pth08t220w and pth08t230w using Turbo trans for the following requirements

1) Vin=11.5 – 12.5, Iout=50A, Load step = 25A, Max voltage deviation=40 mV

T2 calculator suggests Rtt = 0 , Cout = 8298 uF

So I choose 13* 680 uF (T530D687M003A(1)E010 with ESR = 10 m ohm) and In parallel I place 47uF ceramic and 2.2 uF ceramic

2) Vin=11.5 – 12.5, Iout=16A, Load step = 12A, Max voltage deviation=45 mV

T2 calculator suggests Rtt = 0 , Cout = 1546 uF

So I choose 5* 330 uF ((T530D337M006A(1)E006 with ESR= 6 m ohm) and In parallel I place 47uF ceramic and 2.2 uF ceramic

3) Vin=11.5 – 12.5, Iout=6A, Load step = 4.5 A, Max voltage deviation= 50 mV

T2 calculator suggests Rtt = 0 , Cout = 2258 uF

So I choose 7* 330 uF (T530D337M006A(1)E006 with ESR= 6 m ohm) and In parallel I place 47uF ceramic and 2.2 uF ceramic

47 uF(C3216X5R0J476M) and 2.2uF (C1005X5R0J225K) from TDK will be used

Regards,

Chandana

Regarding failures on LMD18245 Stepper Motor Driver

arun achoora — Wed, 27 Mar 2013 07:33:44 GMT

Hi All,

We have a design with LMD18245 Stepper Motor Driver .

Here we could notice -5V noise on the winding connections(OTU1 and OUT2 pins) .Recommended maximum negative voltage(due to the forward bias of body diode) is -1.5V.

Has anyone came across such a situation?

Please let me know.

PTH08T210W design for 1V 10A to 25A Variable supply

Harshad Chirutkar — Mon, 27 Sep 2010 16:49:32 GMT

hi,

I want to design power supply with 1V output with 10A to 25A variable output current. with

PTH08T210W module.

can anyone help me how to work out

PTH08T250W Prebias Startup Capability

Xuezhuan — Wed, 20 Mar 2013 02:20:43 GMT

Hi Expert,

In our design, 1.8V back feed to 3.3V, 1.8V is PTH08T220(12V to 1.8V), 3.3V is PTH08T250W(12V to 3.3V).

PTH08T250W datasheet describe the feature of Prebias Startup Capability at page31, I'm not sure if my understand is right: we can use this method to protect the POLA DC/DC

(1) disable Track function

(2) Input voltage must always be greater than output AND the backfeed voltage. In our design, 12V>3.3V&1.8V.

Should above two items be met at the same? Are our power design safte?

TPS84259 WEBENCH error

Paul Bar — Mon, 18 Mar 2013 12:22:58 GMT

Hi,

I have imported the simulation from WEBENCH (TPS84259) to altium designer and the pad are inverted. I didn't know how to tell TI, so I'll post it here instead. I looked at the datasheet and evaluation module and the pad in the middle should be mirrored.

Paul

DCP021212U

Randy Marsh — Tue, 19 Mar 2013 17:09:20 GMT

Hi, i want to use a DCP021212U IC (SO-28 Package) as an Isolated Voltage Source for a HighSide-Fet application.

Im currently testing the Device and there is a problem:

The input Voltage is 12VDC but the Output Voltage on the output side is about 24V and should be 12V ,too.
I also checked the Device Description, its actually a DCP021212U (not DU or something elese).
The input Capacitor is 2.2uF and the output capacity is 0.33uF. Both Ceramic , placed close to the IC.

Is it possible, that the device is damaged somehow? I cant find any solutions in the datasheet.

Thanks for your support

How to dynamically vary the output voltage of a PTN78060H/W

Lloyd Strickler — Mon, 18 Mar 2013 17:50:51 GMT

We are looking at using a PTN78060H/W module on a board (there are two different configurations that require different output voltage ranges thu the two parts) but we need to be able to adjust the output voltage depending on various factors that change over time. The four choices we came up with were (and the respective major negatives)

a JFET with high on resistance on VCR mode (most of these are going or have gone obsolete),
Switching various fixed resistors in using MOSFETs (chews up I/O quickly)
Digital pots (we don't have enough information to know if this is safe to do)
Feed an external voltage/current into the node to adjust the feedback (not enough information to design the circuit)

For the digital pot one we need to know what is the highest voltage seen at the adjust pin with a 50K resistance to ground (unprogrammed resistance).

For the external voltage one we have a DAC with a 0-2.5V output available, how do we convert this to something that the converter will accept without disturbing stability. I know use an opamp to scale/sum and a resistor/opamp to convert to current if necessary but not knowing the internal proprietary circuitry this isn't an easy task.

ptn78020

Giora Eytan1 — Thu, 14 Mar 2013 06:42:15 GMT

Hello,

The day before yesterday I asked for the UL report of PTN78020 and PTN78060.

I got the doc that certified the UL - but I need the full report, especially:

"the condition of acceptability when installed In the end user equipment".

If you have it I would appreciate sending it to me.

Regards,

Giora

PTR08060W failures - looking for hints and ideas

David Chirgwin — Wed, 13 Mar 2013 10:12:55 GMT

My circuit has a 12V input and uses a PTR08060W to provide a 3.3V rail and a PTR08100W to provide a 5V rail.

The 5V and 3.3V rails are powering a bunch of circuitry including processor, USB controller, Ethernet PHY, DRAM etc. but not heavy inductive loads like motors or solenoids.

Both modules have the recommended capacitors on inputs and outputs.

The 5V rail seems to be fine, but the 3.3V rail is failing after several hours of operation.

So far I have made two boards of this new design. One board failed with a serious over-voltage (the 3.3V rail went up to 12V). Examining the PTR08060W showed that the high-side MOSFET was a direct short circuit (when unpowered).

The other board has failed with under-voltage (3.3V rail has gone down to about 1V). Examining the PTR08060W showed that the high-side MOSFET has a resistance of 11 Ohms (even when the module has no power and is removed from the board). On a good module this is open circuit (when unpowered).

On both boards, the low-side MOSFET is open circuit (when unpowered), as you would expect.

Has anyone encountered this failure mode before?

I'm assuming that the input is OK (i.e. no excessive transients) because the PTR08100W is fine on both boards. Also, my 12V input rail has a 15V zener clamp to limit transients.

Anyway, I'm looking for ideas and hints about what might be causing the problem.

All comments / suggestions gratefully received.