EKM033 LED Driver step-down 4-30V

Part.no: 41036499

EKM033 is a step-down (buck) converter for driving high-power LEDs, LED strips and arrays. The module is based around the highly efficient LED driver IC TPS92200 from Texas Instruments.

The module converts a higher voltage (4V to 30V) to a lower voltage, which is well regulated to match the forward voltage of the connected LED(s). Since the driver regulates the output voltage to a fixed current, any number of LEDs up to the maximum output voltage (99% of VIN), can be connected in series.

The driver features some protection for open load, shorted load, undervoltage and thermal shutdown. Please note that the module does not have any protection against reverse polarity on the input voltage pins and will be damaged by incorrect wiring.

LED brightness can be controlled from 0 - 100% using PWM or an analog voltage between 0 and 2.5V. The onboard 2.5V voltage reference makes it very easy to connect a potentiometer for an analog brightness control.

The LED drive current can be programmed by opening or shorting the solder jumpers, or using an external resistor connected between GND and FB.

Functions

Efficient step-down converter with up tp 99% duty cycle
Drive high-power LEDs from a DC power supply
Programmable output current
Analog or PWM dimming
Onboard 2.5V reference

Specifications

Voltage supply: 4 - 30V
Current limit: 1.5A
Shutdown current: 1uA
Switch frequency: 1MHz
Analog dimming voltage: 0 - 2.5V
PWM frequency range: 100Hz - 2kHz
Dimensions: 32 x 10 mm

Connections

Voltage supply

The module should be supplied with a voltage between 4 and 30V on these pins.

Make sure the input voltage is higher than the combined forward voltage of all connected LEDs.

Danger

The module has no reverse polarity protection and will break if wired incorrectly!

LED output

The LED outputs are marked "LED+" and "LED-". LED+ should be connected to the anode of the first LED. Each successive LED should be wired in series, cathode to anode. The cathode of the last LED should be wired to LED-.

Current preset

The module has two onboard resistors for programming the LED current in two steps. By shorting one or two of the solder jumpers on the back of the pcb, the current can be set to either 330mA (one jumper short, one open) or 660mA (both jumpers short). Default current is 330mA (one solder jumper short, one open).

To program an arbitrary LED current, break both solder jumpers and install a resistor between pins "FB" and "GND".

The drive current can be calculated using the formula: I_LED = V_FB / R_SET.

For the internal 0.3ohm resistor, that means I_LED = 0.099V / 0.3ohm = 330mA.

Some standard resistor values and the resulting LED current:

Resistance	LED current
0.1ohm	990mA
0.15ohm	660mA
0.2ohm	495mA
0.22ohm	450mA
0.27ohm	367mA
0.3ohm	330mA
0.33ohm	300mA
0.4ohm	247mA
0.47ohm	210mA
1ohm	99mA

Dimming

Brightness control for the connected LEDs can be done either using an analog voltage or a digital PWM signal.

The DIM pin can also be used as an on/off switch by shorting it to either V+ or GND.

If nothing is connected to the DIM pin, it will float at 33% brightness. If the dimming function is not required, short DIM to V+ to make the brightness 100%.

If DIM is shorted to GND, the regulator will shutdown and enter power saving.

Analog dimming

The LED brightness can be controlled using an analog voltage, either from an external source or by directly wiring a potentiometer to the module.

The voltage range is 0 - 2.5V, which translates to an LED brightness from fully off to fully on. To limit the range of the external control voltage or the potentiometer, a series resistor can be added to the DIM input.

When dimming using an analog voltage, try to keep the input to output voltage difference at a minimum to reduce flicker.

Maximum tolerable voltage on the DIM pin is 7V.

PWM dimming

Dimming can also be realized using a PWM signal from an external source. PWM frequency should be in the range of 100Hz to 2kHz, but frequencies up to 12kHz is possible.

The PWM input works with 3.3V and 5V logic signals. Maximum tolerable voltage on the DIM pin is 7V.

Datasheet

TPS92200 datasheet