LED Drivers/LCD Bias

Forum Post: The problem in TLC5940

Ssu-Han Huang — Wed, 19 Jun 2013 03:29:00 GMT

Dear,

I combined the TLC5940 with my MCU (nuvoton NUC123) trying to control servo motor; however, there are some problems in the duty of PWM signal. I can’t adjust the right duty even the trend seemed correct. I did not use the dot correction but just gray scale.

Figure 1
Take these two pictures for example, the first is the timing diagram of my SPI command, BLANK, and XLAT. I set 10 in SPI packet, that should mean the low level maintain 10 GSCLK and then PWM transfers to high level, am I right?

Fig.2

But the red frame of the Fig.2 shows that it not only 10 CLK but about 80 CLK during low level. This will cause the fault outcome.

I have done some tests trying to find how could this happen.

1. I change the frequency of GSCLK, this problem still goes and with the higher frequency the number of clock during low level grows.

2. I change the timing of falling edge of BLANK and XLAT pulse, there is no use.

I can’t understand why, the PWM “seems” work, however the outcome has problem. Please give me some instructions! Thanks a lot!

Maxwell

Forum Post: RE: Can strings be shorted to increase LED current

Travis Eichhorn — Tue, 18 Jun 2013 21:24:00 GMT

Paul,

I am assuming you have a single string of LEDs. If this is the case than you can connect the cathode of each string together (ILED1 + ILED2 + ILED3) and sink up to 60mA (max). The boost will figure out which LED string input is the correct feedback path.

Thanks

Travis

Forum Post: LM3409 3Amp/1.5Amp output

Szabolcs Nyulas — Tue, 18 Jun 2013 21:23:00 GMT

Good evening,

I am using the LM3409 to drive four high power LEDS. Two has to be driven with a current of 3 Amps, and the other two with a current of 1.5Amps. (when two LEDS are on the other two is off and vice verse)

I have made a preliminary schematic. Is it possible to make the the change in the output current as it is in the schematic?

My other issue is the input filter. I am searching all over and can not find any application note or reference design on filters.

Thank you.

Forum Post: TLC59711 SPI

Jonathan Ramirez1 — Tue, 18 Jun 2013 18:39:00 GMT

Is it possible to have a daisy chain of TLC59711s and talk to each one separately. So that each LED driver does not latch the same data.

Forum Post: RE: TPS63060 in constant current mode

Chris Glaser — Tue, 18 Jun 2013 13:26:00 GMT

Yes, the TPS63030 EVM is an LED driver that provides a regulated output current through the LED. The TPS63060 should work the same way.

You need to measure the LED current, Vin, Vout, etc. with a scope to see where in your circuit is the error. Make sure that your input supply is not current limited and that the routing to the sense resistor is done well, away from noise sources and short.

Forum Post: RE: TPS65130 Power Saving Mode Efficiency Question

Travis Andreas — Mon, 17 Jun 2013 19:16:00 GMT

I figured that is what happened, but wanted verification. Thank you for the fast response.

Forum Post: RE: Why an LED driver?

rogerio — Fri, 14 Jun 2013 18:11:00 GMT

Adam,

This is a forum for ARM MPUs. Please post your questions related to this topic in our analog forum.

Forum Post: About programmable blinking at TLC59116

masa0301 — Fri, 14 Jun 2013 04:22:00 GMT

I proposal to my coustomer TLC59116.

But my coustomer need to blink each output programmable.

(TLC59116 is only group blinking)

Let me know can I possible to proposal other product?

Coustomer spec

ch:16ch or 8ch

OTHER:BLINK(Each output programmable), Similar TLC59116 spec

Best regards,

masa

Forum Post: LM3406HV DIM2

Moshe Avigdor89344 — Thu, 13 Jun 2013 05:30:00 GMT

Hello,

We like to use DIM2 option with the LM3406HV EVM

Cout=Not assembled

L=33uH

PWM freq is 130Hz into the DIM2 option in the EVM/

Vin=50v

#LED=7 leds

What we see is overshoot in the LED current of about 30% for 1-3 usec

Led current is 200mA

Did replace the led load with a resistor without leads (to eliminate the parasitic inductance) and the current overshoot is the same.

Can you please advice how we can eliminate the current overshoot?

Moshe

Forum Post: TPS92075 eval (slvu813) to meet IEEE C62.41 class A

Hiranthini Alles — Thu, 13 Jun 2013 02:15:00 GMT

The eval board (slvu813) shows the T-filter after the bridge rectifier. In order to meet C62.41 class A 2.5kv 100khz transients I would need to include an MOV (fuse-MOV) before the bridge rectifier. Would this be sufficient to meet C62.41 transients? For a 8.8W output application, I intend to use a 500mA slow-blow fuse (want to keep the fuse to a minimum). Any feedback is most appreciated....thanks.

Forum Post: Motorcycle low/high beam LAMP

Szabolcs Nyulas — Wed, 12 Jun 2013 18:26:00 GMT

Good Evening,

I am designing a new high/low beam motorcycle head lamp using LM3409. The driver board will need to light up 2 pcs of 3 Amp Leds for low beam and the same drive circuit has to light up 2pcs of 1.5 Amp LEDS for high beam independently.. From your experience which is the best solution to make this work? The sense resistor will be 0.08Ohm and when the high beam is on I want to apply at the Iadj pin a voltage of around 0.6V to modify the threshold. Is this a good idea? Do you have an adj ref voltage regulator for this low voltage? Also regarding the input EMI filter. Do you have any application note on designing Input Filters for automotive buck led driver circuits?

Thank you

Forum Post: RE: TLC5951 on shared SPI bus...

Kazuya Nakai — Wed, 12 Jun 2013 06:37:00 GMT

Hello Michael,

I think TLC5951 GSSIN and GSSCK can be connected to serial data and shift clock line of Flash IC. TLC5951 GSLAT should be controlled by dedicated pin of the microcontroller.

Best regards,

Kazuya Nakai.

Forum Post: Can we simulate LM3401 PFET driver using ltspice: spice model

Riar — Wed, 12 Jun 2013 04:26:00 GMT

Is it possible to get a ltspice ( or equivavelt ) model of the LM3401 chip for simulations purposes? if not, could you please recommend another chip with a spice model which is compatible with LM3401?

Thank You.

Forum Post: RE: TPS61199

Marco Hein — Tue, 11 Jun 2013 11:24:00 GMT

Did you get a solution for your problem?

Forum Post: RE: TPS61199

Marco Hein — Tue, 11 Jun 2013 10:22:00 GMT

Did you get a solution for your problem?

Forum Post: LM3409HV Thermal Shutdown.

Alan Hwang — Tue, 11 Jun 2013 06:29:00 GMT

LM3409HV has Thermal Shutdown fuction that threshold is 160C. I tested this fuction.

when temperature is over 160C, LED turn off. but LED flicker before turning Off.

and

When temperature is under 160C, LED turn on. but LED flicker before turning On.

why does it happen???

Forum Post: TPS92075 thermal foldback

Hiranthini Alles — Sun, 09 Jun 2013 02:08:00 GMT

Using the Sluv813EVM and as said in datasheet, I varied R10 from the 8.25K and at ~3.3K the 30V leds started flickering. Until this point, there was no reduction in LED current. I was hoping that when the R10 is reduced the On-time would reduce linearly as stated in the datasheet (I only measured the LED output current) and provide a uniform reduction in the LED output current, but it did not appear to be the case. Could you please explain my mistake....many thanks.

Forum Post: TPS92075 buck-boost

Hiranthini Alles — Sat, 08 Jun 2013 14:09:00 GMT

1) Per SLVU813 EVM Figure 5, and also I measured the FET source voltage, the peak goes to 1.2v. According to the datasheet this is the Vcl(current limit). In normal operation, would the ISNS voltage be ~0.5V, and only on an overcurrent/inductor short would the current limit be reached?

2) The device runs in CCM and at the lower voltages/currents in DCM. Can this design be converted to a DCM/BCM mode only?

Your feedback is most appreciated...thanks.

Forum Post: RE: TLC5927 error detection problem

Philippe GLESSER — Fri, 07 Jun 2013 09:40:00 GMT

Hallo Bernd,

Thanks. I had an older version of the datasheet from july 2008 where it was not indicated.

Beste Grüsse,

Philippe G.

Forum Post: LM3409HVEVAL issue

Jason Teoh — Fri, 07 Jun 2013 04:37:00 GMT

Hi Guys,

I'm using the LM3409 for my project on the LED Tester.

I modified the board to run @ 24V , 3Amps . Since my requirement is 3 Amps for safety i designed for 4 Amps . For that i modified the inductor to 8.2uH, Changed R6 to 11.6kohms, and R9 Sense Resistor to 66mohms.When i power up i can’t able to control the current. i am getting the same what i am pumping in . there is no control over VADJ ( IADJ pin )

Please advice

Regard's

Jason