Page Comparison

Parts:

Red Lights

https://www.digikey.ca/product-detail/en/cree-inc/XPEBRD-L1-0000-00902/XPEBRD-L1-0000-00902CT-ND/5806144

Amber Lights

https://www.digikey.com/product-detail/en/cree-inc/XPEBAM-L1-0000-00903/XPEBAM-L1-0000-00903CT-ND/5806127

White Lights

https://www.digikey.com/product-detail/en/cree-inc/XPEBWT-L1-0000-00EE2/XPEBWT-L1-0000-00EE2CT-ND/5766426

Note: white lights have a forward voltage of 2.9V unlike red and amber lights, which have a forward voltage of 2.2V. Minor design changes will need to be made for white lights.

Drivers:

Constant current boost converter
https://www.digikey.ca/product-detail/en/texas-instruments/TPS61165DBVR/296-27597-1-ND/2340765

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Design

Optimizing PCB thermal performance:

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

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.

Prototype Rev 3:

Fixed the mistakes from Rev 2
Separate LEDs from other components to preserve space
A zener diode is placed parallel to each LED to prevent entire LED string from burning out
LED board will have a heat sink

Testing for Rev 3:

Determine what resistor is required to replace the potentiometer and set the duty cycle of the PWM signal.
Start looking into light dissipation (with mechanical team)

General Testing for Lights:

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