User manual

RE46C190 Demo Board User’s Guide
DS51970A-page 12 © 2011 Microchip Technology Inc.
2.2 SETUP
Before powering the RE46C190 Demo Board, complete the following steps:
1. Place the potentiometer knob on the 2M POT.
2. Attach the six standoffs with screws are provided to act as legs for the demo
board.
3. Start with the switch in OFF state, toggled toward the label R8, and ensure that
Rv2 is turned fully clockwise, to its highest resistance value. The switch (SW2)
and the potentiometer (Rv2) allow the apparent battery voltage (V
DD
) to be
lowered so the low battery operation of the application can be evaluated.
4. Ensure that the 2M POT, used to set the current in the smoke chamber emulator,
is turned fully counterclockwise to set a minimum photodiode current.
5. Ensure there is a preprogrammed RE46C190 in the ZIF socket. The socket’s
pin 1 designator is located near capacitor C2.
6. Insert a CR123A battery in the battery holder, or connect a 3V power supply to
the terminals next to the battery holder (VBAT and GND2).
The RE46C190 Demo Board allows two adjustments when evaluating the RE46C190
device. The first adjustment uses the 2M POT to increase the current to the photodiode
inputs IRN and IRP to simulate a smoke condition, by turning the potentiometer knob
in a clockwise direction.
When switch SW2 is toggled toward the center of the board, Rv2 is able to reduce the
apparent battery voltage (V
DD
) supplied to the IC, when turned counterclockwise.
If a power supply is being used in place of a battery, be sure the current limit is set for
a value greater than 2A. When the boost regulator is operating, it can draw peak
currents greater than 1.0A. A low current limit may cause the power supply voltage to
drop, and may reset the IC. This can appear as a non-specified operation.
Due to the sampling rate of the IC, the potentiometer adjustments do not have an
immediate effect. Refer to the RE46C190 Data Sheet for specific information on timing.
2.3 GETTING STARTED
To emulate the basic smoke detect operation, slowly turn the 2M POT clockwise, until
RLED flashes and the piezo horn sounds. This is the Alarm mode. A piece of tape over
the hole in the piezo horn case reduces the volume of the horn during testing. Turn the
2M POT counterclockwise until the Alarm mode ends. This is the Hysteresis mode of
operation. The GLED flashes to indicate a local alarm, i.e. this particular device has
been in an alarm condition. Press SW1, the Push-to-Test button. The piezo horn will
chirp as an audible indication that the Local Alarm Memory is set. When the button is
released, the Local Alarm Memory is reset to Normal operation. Refer to the
RE46C190 Data Sheet for specific details on device operation in Normal mode.
Repeat the test above, but leave the IC in Alarm mode, and press SW1 to enter the
Hush mode. Continue by turning the 2M POT clockwise to re-enter the Alarm mode.
Refer to the RE46C190 Data Sheet for Push-to-Test and Reduced Sensitivity
operation.
WARNING
The smoke emulator circuit is sensitive to the battery voltage or power supply voltage.
To ensure consistent results from the smoke emulator, be sure the VBAT voltage is the
same as used in the previous tests.