Multi voltage supply
ManAtWork
Posts: 2,176
Maybe, this is not directly related to the propeller, but more a general electronics question. But I'm sure many here have the same problem...
For many of my propeller designs I need multiple supply voltages. For example 3.3V to the propeller, of course, 5V for external loads (servos, encoder...) and 12V for MOSFET drivers. Currently I solve this with a 12V switching regulator and multiple linear regulators. This has the advantage that, first, the 3.3V are clean and stable (good for ADCs), and second, that an overload or short at the external devices does not kill power to the prop as long as that linear regulator limits the current well below the 12V current capacity.
However, as the circuit and code becomes more complex, I'm starting to get heat problems. To reduce the dissipation I'm thinking about changing the switching regulator to 6V and use an LDO for the 5V and a charge pump for the 12V (currently <20mA). So this would cut the heat down to ~ one half.
Another option would be a multi-output switching regulator like the LT3504. However, most of the devices are either far overpowered (for PC applications) or are limited to battery powered applications (input 3.xV lithium cell). Does anybody know a clever solution in the 1W/output range with a wide input range (20..36 or 48V would be ideal)? Currently I need 3.3V/150mA, 5V 150mA and 12V 20mA but a bit headroom wouldn't hurt.
For many of my propeller designs I need multiple supply voltages. For example 3.3V to the propeller, of course, 5V for external loads (servos, encoder...) and 12V for MOSFET drivers. Currently I solve this with a 12V switching regulator and multiple linear regulators. This has the advantage that, first, the 3.3V are clean and stable (good for ADCs), and second, that an overload or short at the external devices does not kill power to the prop as long as that linear regulator limits the current well below the 12V current capacity.
However, as the circuit and code becomes more complex, I'm starting to get heat problems. To reduce the dissipation I'm thinking about changing the switching regulator to 6V and use an LDO for the 5V and a charge pump for the 12V (currently <20mA). So this would cut the heat down to ~ one half.
Another option would be a multi-output switching regulator like the LT3504. However, most of the devices are either far overpowered (for PC applications) or are limited to battery powered applications (input 3.xV lithium cell). Does anybody know a clever solution in the 1W/output range with a wide input range (20..36 or 48V would be ideal)? Currently I need 3.3V/150mA, 5V 150mA and 12V 20mA but a bit headroom wouldn't hurt.
Comments
http://www.digikey.com/product-detail/en/ADP1613ARMZ-R7/ADP1613ARMZ-R7CT-ND/2057805
which has a limited input (2.5 - 5v)
For 5V I use this switching reg:
http://www.digikey.com/product-detail/en/LT1076CQ-5%23PBF/LT1076CQ-5%23PBF-ND/890645
which has a larger input(to 45V). So you could drop your high input to 5V with the switching reg, then boost to 12V and drop 3v3 with the Boost also( Set the output with resistors). Or use an LDO from 5to 3v3 with minimal heat.
You will have zero noticeable heat(to touch) using this config.
LMR14203 for step down (12..36 to 5V).
LMR62014 for boost (5V to 12V).
Both cost ~$1, have a small SOT23-6 case and operate with a small inductor (10..47µH, 1210 to 2220 size)