Parts:
Red LightsLEDs
Color | Forward Voltage | Link |
|---|---|---|
Red | 2.2V | |
Amber |
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2.9V | https://www.digikey.com/product-detail/en/cree-inc/XPEBWT-L1-0000-00EE2/XPEBWT-L1-0000-00EE2CT-ND/ |
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Note: white lights have a forward voltage of 2.9V unlike red and amber lights, which have a forward voltage of 2.2V.
Drivers:
Constant current boost converterLights Links should be double checked to give us the best binning possible (within reasonable price).
Drivers:
Driver | Topology | Applications | Link |
|---|---|---|---|
TPS61165 | Boost | DRLs only | https://www.digikey.ca/product-detail/en/texas-instruments/TPS61165DBVR/296-27597-1-ND/2340765 |
Heat sink:
Calculations:
maximum temperature of Rev3 Lights PCB = 50 C
ambient temperature (generous estimate) = 35 C
power dissipation (red or amber lights) = 2.2V * 6 LEDs * 0.35 A = 4.62 W
power dissipation (white lights) = 2.9V * 6 LEDs * 0.35 A = 6.09 W
Required thermal resistance (red or amber) = (50-35)/4.62 = 3.24 C/W
Required thermal resistance (white) = (50-35)/6.09 = 2.46 C/W
LM3406 | Buck | All except DRLs |
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LM3429 | Buck-Boost | All |
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Heat sink:
See thermal calculations here: Lights Thermal Calculations
Mechanical:
NOTE: Some of the pictures of the mechanical lights layout are no longer valid.
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, however this is to show that we are very constrained for our lights board layouts.
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Design
Optimizing PCB thermal performance:
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