Page Comparison

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https://www.cree.com/led-components/media/documents/XLamp_PCB_Thermal.pdf

LED Drivers

Candidates:

http://www.ti.com/lit/ds/symlink/tps92830-q1.pdf (has multiple channels, but low efficiency)Design

Drivers:
https://www.digikey.ca/product-detail/en/allegrotexas-microsystems-llc/A8518KLPTR-T/620-1658-6-ND/5012704 (multiple channels, high efficiency, driving current is a bit low)instruments/TPS61165DBVR/296-27597-1-ND/2340765

Prototype Rev 1:

3 LEDs in series with no additional parts. Lights were sufficiently bright and stable, but became very hot (around 80 C) very quickly.

Prototype Rev 2:

6 LEDs in series driven by a boost converter. PWM signal provided by 555 timer. Potentiometer included in 555 timer circuit to allow experimentation with duty cycles. LEDs and current sense resistors are kept on a separate board to account for the physical constraints of the car.

List of issues:

• Lack of decoupling capacitors
• Incorrect capacitor value for 555 timer (which set the incorrect frequency for the CTRL pin on the driver).
• Pins configured incorrectly
• Lack of ground pour for stability
• Inductor was not placed close enough to the potentiometer (no boost was measured).

Further Testing for Rev 2:

• Measure current at the connectors on startup to determine whether additional capacitors are required at the connectors.
• Measure power dissipation and efficiency of the driver.

Next Steps for Rev 3:

• Fix the obvious mistakes
• Determine whether heat dissipation for the LEDs is done through electrical ground (move current sense resistors to the main board if it is not).
• Calculate expected power dissipation of the driver, and determine expected temperature from it.
• Determine what voltage is required to replace the potentiometer and set the duty cycle of the PWM signal.

General Testing for Lights:

• Measure brightness of the LEDs.
• Ensure that the driver is boosting the voltage properly.
• Ensure that temperature is within safe limits (<100 C).
• Measure the stability of the LEDs by using a varying voltage.
• Measure the current and voltage on startup at the connectors.