EKM032 LED Driver Step-up 3-5V
Part.no: 41036497
EKM032 is a step-up (boost) converter for high-power LEDs, LED strips and arrays. EKM032 is based around the highly efficient LED driver IC TPS61169 from Texas Instruments.
The module converts a low voltage (2.7V to 5.5V) to a higher voltage, which is well regulated to match the forward voltage of the connected LEDs.
Since the driver regulates the output voltage to a fixed current, any number of LEDs can be connected in series, up to the maximum output voltage 38V.
Please note however that not all combinations of input voltage, output current and number of LEDs are possible as the regulator is limited in current on the input side. An example: 3V in, 20V out, 200mA LED current will draw more than 1.2A through the regulators switches, which it cannot handle. If the input voltage is raised to 5V, the current through the regulator will decrease to around 800mA, which is within specs. See the table below for more information.
The driver features some protection for open load, undervoltage and thermal shutdown.
Brightness can be controlled from 0 - 100% using PWM and the drive current can be programmed using an external resistor connected between GND and FB.
Functions
- Highly efficient design, up to 90%
- Drive LEDs in series from battery or USB
- Easy brightness control with PWM
- Programmable current limit
Specifications
- Voltage supply: 2.7 - 5.5V
- Maximum output voltage: 38V
- FET switch limit: 1.2A
- Default output current: 204mA
- Switching frequency: 1.2MHz
- Dimensions: 30 x 10 mm
Connections
Voltage supply
The module should be supplied with a voltage between 2.7 and 5.5VDC on these pins.
The included 3.5mm pitch terminal block can be used for easy wiring. The pattern also fits 2.54mm headers or wires soldered directly to the board.
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
First use requires bridging of the solder jumper on the back of the board or installing a through-hole resistor between the pins "FB" and "GND".
The board has an onboard 1 ohm resistor to set the maximum output current to 204mA, suitable current for driving 1W LEDs. To use the internal resistor, simple join the two copper pads using solder.
An external resistor can be used to program a different drive current. Maximum peak current for the regulator is limited to 1.2A, but different combinations of input voltage, output voltage and drive current can make the available current to the LEDs limited.
The drive current can be calculated using the formula: ILED = VFB / RSET.
For the internal 0.3ohm resistor, that means ILED = 0.099V / 0.3ohm = 330mA.
See the table below for some usable resistor values vs. input voltage and number of LEDs.
0.5ohm (408mA):
| 1 LED | 2 LEDs | 3 LEDs | 4 LEDs | 5 LEDs | 6 LEDs | |
|---|---|---|---|---|---|---|
| 2.5V | --- | --- | --- | --- | --- | --- |
| 3.0V | --- | --- | --- | --- | --- | --- |
| 3.5V | OK | OK | --- | --- | --- | --- |
| 4.0V | OK | OK | --- | --- | --- | --- |
| 4.5V | --- | OK | OK | --- | --- | --- |
| 5.0V | --- | OK | OK | --- | --- | --- |
| 5.5V | --- | OK | OK | OK | --- | --- |
1.0ohm (204mA) = R2:
| 1 LED | 2 LEDs | 3 LEDs | 4 LEDs | 5 LEDs | 6 LEDs | |
|---|---|---|---|---|---|---|
| 2.5V | OK | OK | --- | --- | --- | --- |
| 3.0V | OK | OK | OK | --- | --- | --- |
| 3.5V | OK | OK | OK | OK | --- | --- |
| 4.0V | --- | OK | OK | OK | OK | --- |
| 4.5V | --- | OK | OK | OK | OK | OK |
| 5.0V | --- | OK | OK | OK | OK | OK |
| 5.5V | --- | OK | OK | OK | OK | OK |
3.0ohm (68mA):
| 1 LED | 2 LEDs | 3 LEDs | 4 LEDs | 5 LEDs | 6 LEDs | |
|---|---|---|---|---|---|---|
| 2.5V | OK | OK | OK | OK | OK | OK |
| 3.0V | OK | OK | OK | OK | OK | OK |
| 3.5V | --- | OK | OK | OK | OK | OK |
| 4.0V | --- | OK | OK | OK | OK | OK |
| 4.5V | --- | OK | OK | OK | OK | OK |
| 5.0V | --- | OK | OK | OK | OK | OK |
| 5.5V | --- | OK | OK | OK | OK | OK |
PWM brightness control
The PWM input can be used for dimming the connected LEDs from 1% to 100%.
The PWM signal should be in the range of 5kHz to 100kHz. Logic low is below 0.4V and high is above 1.2V. Maximum tolerable voltage on PWM pin is 7V.
When the PWM input is pulled low for longer than 2.5ms, the regulator shuts down.
Leave the PWM pin unconnected if no dimming is required.
Datasheet
Mechanical dimensions
