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Datasheet of A1101R04C00GM - IC RADIO MOD 433MHZ CONN 24-LGA
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A1101R04C – User’s Manual
Page 19 of 26
Release Date 02/20/12
3.4.
Recommended Layout
(Dimensions in mm)
Figure 6 Recommended PCB layout.
3.5.
Power Supply Considerations
Noise on the power supply line reduces the sensitivity of a receiver and modulates onto a
transmitters signal, both of which causes a degradation of link quality and hence a reduction in
range.
The A1101R04C radio module has an integral ferrite bead in the supply line from pin 18 (Vdd)
and a decoupling capacitance to reduce any noise on the incoming power supply line. This
arrangement will eliminate most supply voltage noise. In particular noisy environments
(switching regulators, motor controls, etc.), it may be necessary to add additional noise
reduction means.
Pin 7 (Vdcoup1) is connected to the module’s internal supply line after the ferrite bead and
decoupling capacitors and can be used to probe the noise at module level. The noise level
measured on pin 7 should not exceed 120mVpp when in transmit or receive mode, it may
however exceed this value when setting up or accessing data to/from the FIFO’s while not
actively transmitting or receiving.
If the level measured is exceeding the above limit, steps should be taken to ensure maximum
range, including:
Adding decoupling capacitance to pin 7 (Vdcoup1).
Adding additional filtering in the supply line.
Adding an LDO in the supply line (the TPS734xx low Dropout Regulator from TI is
recommended).
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