Here is shown a tiny LED driver, even tinier that Glighter-S. Glighter-A is the result of an effort in wanting to implement, in a low cost configuration, an analog control with zero energy waste. Also, I found a board more beautiful when small enough to fit it everywhere, so I endup with this Hysteretic buck converter which requires less component than Glighter-S.

My concept behind is to always use LEDs reliably and efficiently, since technology allow us to do so easily, today, without relying to shady chinese parts, for our hobby projects.

Product brief

This is a 40W Power LED driver, in order to power and drive one or more LEDs, ideally in a strip. Like for Glighter-S, the Glighter-A module includes some of features that I consider important in one small driver, such as wide input voltage capability, fail-safe feature, size and, among the digital control, having the analog too. But now with more power capability.

The connectors and controls are kept with minimum footprint: just the control, power supply and the output of the LED. The single pin control can be used to combine analog and digital dimming together.

It uses the hysteretic drive method: lower components and lower footprints, are not for free. This method in fact uses a variable switching frequency, meaning that EMI filtering has to be done carefully, as there is no local oscillator. But the fact that the frequency range is from 500kHz and below, makes it actually not an issue, most of the time. I provide advice if you are not sure.

Getting more specific

Can be driven from any 3.3V or 5V or higher logic, with analog and PWM signals, allowing precise light adjust level, customizable with lumen stability of the LED down to 1%* and below. With an overall consumption of 400nA in standby, is well suited for battery powered devices which are requiring high efficiency during operation and low quiescent current in standby.

Due to the high input voltage range up to 40V, with full current of 1000 mA, can be used to power up big LED based luminaires and also being powered with battery packs with not intermediate voltage conversion, keeping the efficiency at maximum levels. The parts sold are designed to deliver maximum 605 mA, to maintain compatibility with most power LEDs. A customization is possible under request, or can be done by changing a resistor.

Lower maximum currents can be achieved by limiting the control voltage at the input - see below.

*Tested with LXW8-PW40 LED.

You need this if...

...you need a cheap and dependable LED driver

...space available for a board is a concern

...you need analog and/or PWM control

Product summary

• Technology: Infineon ILD4001 hysteretic switching buck regulator
• Input voltage: LED Vf + 2.5V to 40V
• Output voltage (LED Vf): 0.5V to 39V
• Sourced current: up to 1A on request (set to default 605mA)
• Size: 13mm x 21mm
• Efficiency up to 95% with 4 LEDs with 3V each
• Operating Temperature: -40°C to 60°C
• Safety features:
  • Short circuit immune
  • Open circuit immune
  • Safe state (off) when no control is applied

• Overtemperature protected

• Input control methods: ANALOG and PWM

• PWM control: fully off with < 1V, fully on with > 2.4V
• Analog control: >1V to <2.3V linear current swipe.
  • 2.3V = 100% nominal current. 1V = 20% nominal current.
  • Analog slope in % of output maximum current: 60 %/V (within 20% - 100% dimming)

• Control frequency PWM: 3 kHz for 10:1 digital contrast ratio. 400 Hz for 100:1 digital contrast ratio. 180 Hz for 200:1 digital contrast ratio.

• Analog contrast ratio: up to 4.5:1. Can be multiplied with the abovementioned digital contrast ratio.

• Low output current switching noise: on-board filtering to a further reduction of 9 dB (Tested with LXW8-PW40 LED at 600mA)

How to use it

The driver has 3 input pins

• VIN: the input voltage
• GND: ground
• EN/PWM: the control pin

Any board handling any type of digital signal can be used to drive the EN pin. Any signal lower that 0.5V result in a full off driver; any signal higher than 2V fully turns on it. A swing in between makes analog regulation of the current. This means also that PWM can be used, of any voltage swing up to the power supply!

The output is made by 2 pins

• LED anode
• LED cathode

Just connect the LED respecting the polarity, or the LED can fail (read the datasheet of your power LED!).

Setting the current

Assuming that the input voltage is respected, the driver can light any LED which is designed to take around 605mA. A sense resistor is used to set this current: a different sensing value can be used to adjust the output current. The sense resistor can be changed (also upon request).

When buying these products, you are supporting me in investing in improvements for next revisions and new ideas.