RFD21733 Datasheet, PDF (20/76 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
Eval Board Top and Bottom View Pinout for All Eval Boards
Eval Board Power Supply and Logic Levels - Important
There is an internal 3.3 Volt (LDO) on the eval boards. At the (pin 2) +V input pin, you can supply
2.1VDC minimum and a maximum of 3.6VDC. When your supplied voltage is between 3.4V and 3.6V the
internal regulator is in regulation and the internal supply to all parts will be 3.3V, and all signals on pins
9-12 will be at 3.3V logic. When 2.1V to 3.4V is supplied the internal 3.3V regulator is of regulation and
tracks the input voltage (minus about 100mv overhead). If you supply 2.5V your logic will be at 2.4V,
and if you supply 2.1V your logic will be at 2.0V. The internal 3.3V regulator accept up to a 5V supply
input, but at 5V supply, your logic levels on pins 9-12 will be at 3.3V, SO USE CAUTION. So you will
need to use 3.3V to 5V logic level shifters to run properly at 5V or you will cause damage to the module.
When using a 5V supply, a very quick 5V level shifter method (not to be used for production) just for
testing, which works in some cases would be to use a 22K resistor in series between the eval boards
3.3V logic and your 5V logic. There is a 47k pull down resistor internal to the Eval Boards ONLY (NOT
THE MODULE or RFDANT) on pin 9-12 and this is just enough to switch the logic levels in both
directions for a quick and dirty level shifter. There are NO 47k pull down resistors on the Modules or
RFDANTs, so you must add your own pull-downs or pull-ups accordingly.
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