Proto Board power options

Falcon

I plan to use a Proto Board (non-USB) on a mobile rover platform, but will not use it to drive any servos. The manual states the power requirement as 6-9 VDC. The rover has 24VDC and 12VDC available from the SLA batteries, and 5VDC from the BEC on-board the Sabertooth 2x25 motor controller, but all are outside the suggested input. I've run a Protoboard on a 12 VDC wall wart but the SLA can often output up to 14 VDC when fully charged. The LM1086-5.0 datasheet states the Absolute Maximum Rating for input voltage as 25VDC with the following note:

Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test conditions, see the Electrical Characteristics.

Question: Would I be safer injecting the regulated 5VDC from the BEC into the Proto Board after VR1 (LM1086-5.0) and VR2(LM1086-3.3), or using one of the SLA batteries that will range from 11-14 VDC?

Thanks,

falcon

Alarus

I'm thinking that 25 V is critical for her. Everything will depend on the current and temperature.

Can use DC-DC?

ratronic

Falcon I have wired the power supply pin of a BEC connector into the connection between the 5.0V reg. output and the 3.3V reg. input on the Propeller Proto-board to power the proto board in my quad copter in flight. Make sure to connect ground from the BEC connector to ground on the Proto-board. EDIT: I had the regulators listed backwards it is correct now.

Falcon

Alarus, Yes...I want to stay away from that 25VDC limit. I suppose I could use the 12 VDC to the coax power input if need be.

Ratronic, It's good to hear that injecting that 5 VDC will work. I imagine you wouldn't do it in a critical situation like a quad copter if there was much chance of it frying itself.

Thanks for the replies,

falcon

groggory

There are many ways to solve this.

First of all you should realize that the regulators on the proto board are linear regulators and their goal in life is to eat up the juice in your battery. Look at a buck regulator if you care about efficiency.

What load are you planning on running on the prop proto board?

Falcon

I have the two 35 AH SLA batteries onboard so I'm not worried about power consumption. Good call though...I've had projects where every mA counted.

I plan to power an SN75176 Differential Bus Transceiver and a 100 mW XBee.that draws 180 mA. Both will run on the 5 VDC input so essentially no load on the Proto Board regulator.

falcon