Pololu 0J5840, Руководство пользователя

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applications that require a lot of current. For example, 15 V batteries regulated down to 5 V
with a linear regulator will lose two-thirds of their energy in the linear regulator. This energy
becomes heat, so linear regulators often need large heat sinks, and they generally don’t work
well with high-power applications.
• Switching regulators turn power on and off at a high frequency, filtering the output to
produce a stable supply at the desired voltage. By carefully redirecting the flow of electricity,
switching regulators can be much more efficient than linear regulators, especially for high-
current applications and large changes in voltage. Also, switching regulators can convert low
voltages into higher voltages! A key component of a switching regulator is the
inductor , which
stores energy and smooths out current; on the 3pi, the inductor is the gray block near the ball
caster labeled “100”. A desktop computer power supply also uses switching regulators: peek
through the vent in the back of your computer and look for a donut-shaped piece with a coil
of thick copper wire wrapped around it – that’s the inductor.
The power management subsystem built into the 3pi is shown in this block diagram:
The voltage of 4 x AAA cells can vary between 3.5 – 5.5 V (and even to 6 V if alkalines are used).
This means it’s not possible simply to regulate the voltage up or down to get 5 V. Instead, in the
3pi, a switching regulator first boosts the battery voltage up to 9.25 V (Vboost), and a linear regulator
regulates Vboost back down to 5 V (VCC). Vboost powers the motors and the IR LEDs in the line
sensors, while VCC is used for the microcontroller and all digital signals.
Using Vboost for the motors and sensors gives the 3pi three unique performance advantages over
typical robots, which use battery power directly:
• First, a higher voltage means more power for the motors, without requiring more current and
Pololu 3pi Robot User’s Guide © 2001–2019 Pololu Corporation
5. How Your 3pi Works Page 14 of 85