Texas Instruments TRF4900, Руководство пользователя, Страница: 24 / 45

Standard PC Parallel Port
2-13
Evaluation Board
2.6 Jumper Connections
The default position of the jumpers on the TRF4900 EVM are configured as
shown below.
1
2
To R1 and C2 (Loop Filter)
To R5 and R6 (VCO Tank)
1
2
3
To Mode Test Point
To Ground
1
2
3
To STDBY Test Point
To Ground
1
2
VR1 output (VCC1)
To LED3 anode (Power on LED)
Denotes Default Connection
JP1
JP3
JP2
JP4
JP1 is a 0-
Ω
0603 resistor
JP2 Default is not installed
JP3 Default is not installed
To V
CC2
To V
CC2
JP4 is a 0-
Ω
0603 resistor
2.6.1 Jumper Description
The jumpers on the TRF4900 EVM are used for the following purposes:
-
JP1
Jumper JP1 connects the VCO tank circuit to the loop filter of the PLL
circuit. The only reason to remove jumper JP1 is to test the tuning range
of the VCO tank circuit with an external power supply. The default state for
jumper JP1 is JP1-1 to JP1-2. Jumper JP1 is a 0-
Ω
0603 resistor.
-
JP2
Jumper JP2 can be used to pull the STDBY line up to V
CC
(JP2-1 to JP2-2)
or pull down to ground (JP2-2 to JP2-3), if a computer connection is not
installed. The primary purpose for JP2 is as a test point to monitor the state
of the STDBY line. The default state for jumper JP2 is not connected.
-
JP3
Jumper JP3 can be used to pull the MODE line up to V
CC
(JP3-1 to JP3-2)
or pull down to ground (JP3-2 to JP3-3), if a computer connection is not
installed. The primary purpose for JP3 is as a test point to monitor the state
of the MODE line. The default state for jumper JP3 is not connected.
-
JP4
Jumper JP4 connects the Power-On LED to the output of the VR2 voltage
regulator. The default state for jumper JP4 is JP4-1 to JP4-2. Jumper JP4
is a 0-
Ω
, 0603 resistor.