RFD21733 Datasheet, PDF (31/76 Pages) List of Unclassifed Manufacturers – Compliance Approved 2.4 GHz RF Transceiver Modules with Built-In RFDP8 Application Protocol

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7/10/2011 1:40 AM
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RFD21733 • FCC • IC
RFD21743 • FCC
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RFDP8
RF Module
RFD21733
RFD21735
RFD21737
RFD21738
RFD21739
RFDP8
RFDANT
RFD21742
RFD21743
RFD21772
RFD21773
KEYFOBs
The Active RFID Transmitter transmits a packet with its ESN every 2 seconds when the three inputs IN1, IN2, IN3
are all at a low logic level. If any of the three inputs go high, the module transmits the state of all three inputs
every 15 ms, until all three inputs are low. The logic inputs should be tied low if they are not used in the end
application.
The module is active during transmit for 15ms, but remains in an ultra-low power mode for the rest of the 2
second interval. The average power over time is measured in microamps, such that a CR2032 battery should
provide about 60 days of continuous use. If you wish to have longer usage you can contact
[e-mail] for intervals greater then 2 seconds, for example 20 seconds would estimate to about two
years.
During the 15ms transmission times the current consumption is about 15mA and during the roughly 2 seconds the
current is about 2uA. The average current with a 2 second interval is about 120uA. The average current with a
30 second interval is about 10uA, and 60 second interval is about 6uA. Estimated runtime of many years can be
achieved 30 second range due to the very low average current consumption.
If you determine that you need a different period of transmission other than the 2 seconds, a shorter period or a
longer period, then simply use Mode 1 shown below and use your own controller to pulse one of the 3 inputs at
the desired period and it will perform exactly the same function as the RFID transmitter Mode 0.
If longer periods of use are required, a larger battery can be used to allow it to run up to years of time without
replacing the battery, or contact RF Digital to inquire about a custom time setting which will reduce the
transmission interval thus reducing the average power consumption.
The Mode 0 is effectively Mode 1, except, in addition to Mode 1 features, the module will internally cause input 1
to transmit on its own every 2 seconds. So Mode 0 can be looked at like it is a dual mode, it is functioning as an
RFID transmitter as well at the same time it is available to use as a 3 input switch transmitter.
If you use a Mode 2 or Mode 3 receiver with a Serial UART output you can easily detect the difference between
transmissions which were caused by the RFID interval automatically or by the user pressing a button to cause
IN1, IN2 or IN3 to go high which causes an immediate transmission, regardless of RFID interval.
Note if you connect a series resistor and an LED to the LED output pin, that will draw extra current during the
15mS transmission time, it is good to have it there for testing, but take that into consideration when you go to
production for your battery runtime.
If you would like to use all or any one of the three switch inputs as button inputs, then simply place a pull down
resistor around 47k or smaller on the inputs which you will be connecting to a pushbutton, so when you press the
pushbutton the input will go high and when you release it the input will be pulled to ground by the 47k resistor.
The Reset Pin has a 3.3k Pull Up, internal to the Module and RFDANT.
The Factory Pin has a 3.3k Pull Down, internal to the Module and RFDANT.
There are no internal pull ups or pull downs on any other pins except for “Mode Select 0”, which has an internal
13k pull down temporarily applied when the device comes out of reset or after power up for about less then a
millisecond. All other pull downs or pull ups must be applied by you, externally to the Module or RFDANT. If you
are using the RFD Eval Boards (RFD21737, RFD21738, RFD21739, RFD21772, RFD21773) there are 47k pull
downs on these Eval Boards, see the Eval Board Schematic for reference on Pull Downs and which Pins they on.
Always send screen captures of your schematics and layouts to [e-mail] for review.
Free Applications Support • Email your application questions to [e-mail]
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