MRF24J40MB-I Datasheet, PDF (136/156 Pages) Microchip Technology – IEEE 802.15.4™ 2.4 GHz RF Transceiver

MRF24J40
4.2 External PA/LNA Control
External PA, LNA and RF switches can be controlled by
the MRF24J40 internal RF state machine. Figure 4-3
shows a typical application circuit with external PA,
LNA and RF switches. Setting TESTMODE
(0x22F<2:0>) bits to ‘111’ will configure pins, GPIO0,
GPIO1 and GPIO2, to operate according to Table 4-1.
The external PA/LNA timing diagram is shown in
Figure 4-4.
TABLE 4-1: GPIO EXTERNAL PA/LNA
SIGNALING
GPIO
Receive Transmit
Maximum
Current
Source
GPIO0
GPIO1
GPIO2
Low
Low
High
High
High
Low
4 ma
1 ma
1 ma
FIGURE 4-3:
Antenna
EXTERNAL PA/LNA BLOCK DIAGRAM
RF
Switch
LNA
Enable
LNA
PA
PA
Enable
RF
Switch
Balun
RFP
RFN
MRF24J40
GPIO0
GPIO1
GPIO2
DS39776C-page 136
Preliminary
© 2010 Microchip Technology Inc.