4.1. Components of the RC Switch with Medium Low-Side MOSFET

Pololu RC Switch with Medium Low-Side MOSFET, labeled top view.

The Pololu RC Switch with Medium Low-Side MOSFET has 12 smaller through holes spaced 0.1″ apart that fit 0.1″ header pins and four larger holes that fit 3.5 mm screw terminals.

RC interface

The GND, VIN, and RC IN pins make up the switch’s RC interface and can be connected directly to an RC receiver or servo controller:

  • The GND pin is the ground or reference voltage.
  • The VIN pin is the power input.
  • The RC IN pin is the RC signal input. The switch measures the width of pulses on this line and uses that to decide whether to activate or not.

Power

The VIN pins power the basic functions of the board and need to be connected to a power source between 2.5 V to 16 V. This allows the board to be powered from a 4- or 5-cell NiMH or NiCD battery pack through an RC receiver or separately.

The VCC pin connects to the output of the onboard regulator and is 5 V when the board is powered with a source that is greater than or equal to 5 V and approximately equal to VIN when it is below 5 V. VCC is also the gate voltage that is used to turn the MOSFET on, so it should be noted that lower VCC voltages will lead to higher MOSFET on resistances, which in turn limits the maximum current the device can switch.

Load interface

The LOAD LOW and LOAD HIGH pins are connections for your load and load supply. The LOAD LOW pins are normally disconnected from GND, but when the switch activates the MOSFET turns on and connects LOAD LOW to GND. There is a flyback (also known as a “freewheeling”) diode between LOAD LOW and LOAD HIGH. The board’s MOSFET can deliver up to 15 A with VCC at 5 V and can handle load supply voltages up to 30 V. More details on connecting your load and load supply to the switch can be found in Section 4.2.

Outputs and indicator LED

The RC switch provides feedback about what state it is in via a yellow indicator LED. The LED behavior is described in Section 8. Status information is also provided by two additional outputs:

  • The GOOD pin indicates the presence of a valid RC signal (10–330 Hz pulse rate, 0.5–2.5 ms pulse width).
  • The OUT pin indicates whether the MOSFET is on.

When these outputs are high they will be at the same voltage level as VCC. When low, these outputs will be at 0 V (ground). These outputs do not have resistors in series with them. Each output can source or sink up to 25 mA.

Configuration interface

The learning mode jumper on both the top and bottom of the board can be used to get the device into learning mode and configure it. The configuration procedure is described in Section 9.

Pololu RC Switch with Medium Low-Side MOSFET, bottom view with dimensions.

Included hardware

A 12-pin 0.1″ straight breakaway male header and two 3.5 mm 2-pin terminal blocks are included with the Pololu RC Switch with Medium Low-Side MOSFET. The header pins can be soldered in and used to connect the RC switch to perfboards or breadboards. Please note that the included terminal blocks are only rated for 10 A; for higher power applications, use thick wires soldered directly to the board.

Pololu RC Switch with Medium Low-Side MOSFET with included hardware.