Pulse-Width Modulation - sparkfun PRT-13144 Hook-Up Manual

Pulse-width Modulation

The PWM output generates a signal with a duty-cycle that is proportional to
the current Touch Potentiometer value. A value of zero results in a PWM
output of 0% duty cycle (off). A value of 255 (full-scale) results in a PWM
output of nearly 100% duty cycle (on).
Analog I/O
The Touch Potentiometer Analog IO signals consist of the [AD5262] wiper
and wiper power supply signals. The AD5262 supports two separate digital
20kΩ potentiometers, each with two terminals and a wiper connection. They
have their own power supply connections allowing the voltage levels on the
potentiometers to exceed the +5 volt logic power supply (see important note
below).
Pin
Label Function
A1, A2 A Terminals for potentiometer 1 and 2
W1, Wiper Terminals for potentiometer 1 and 2
W2
B1, B2 B Terminals for potentiometer 1 and 2
V+ Positive Power Supply. Connected at the factory to the 5V logic
signal by jumper J1. With J1 removed this may be connected to
a positive voltage up to 15V. Note the sum of |V-| + |V+| must
be 15V or less.
V- Negative Power Supply. Connected at the factory to ground by
jumper J2. With J2 removed this may be connected to a
negative voltage down to -5V. Note the sum of |V-| + |V+| must
be 15V or less.
Current Limitations: The maximum amount of current allowed
through the A or B to W pins is 5mA continuous, 20 mA intermittent.
Important Notes about V+ and V-
Care must be taken with V+ and V- to prevent damage to the ICs on
the Touch Potentiometer.
1. V+ and V- must always be connected to power and should be
powered before or at the same time voltages appear on the A, B and
W signals and 5V input.
2. By default, V+ is connected to 5V with jumper J1 and V- is
connected to ground with jumper J2. Voltages on the A, B and W
signals should not exceed the range of 0 - 5V with these jumpers
installed. Remove these jumpers by removing the solder blob if a
different power supply will be connected to V+ and/or V-.
3. The maximum voltage potential between V- and V+ is 15 volts. V-
maximum is -5V. V+ maximum is 15V.
4. Electrical noise on V- and V+ may be coupled into the signal
Page 4 of 14