MAX3540EVKIT Просмотр технического описания (PDF) - Maxim Integrated
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MAX3540EVKIT Datasheet PDF : 10 Pages
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MAX3540 Evaluation Kit
Connections and Setup
This section provides a step-by-step guide to testing
the basic functionality of the EV kit in UHF mode.
Caution: Do not turn on DC power or RF signal gen-
erators until all connections are completed:
1) Verify that the JP1 and JP6 shunts are removed, the
JP2 shunt is installed, and JP11 and JP12 have
shunts across pins 1-2.
2) With its output disabled, set the DC power supply to
+3.3V. Connect the power supply to the +3.3V
(through an ammeter if desired) and GND1 termi-
nals on the EV kit. If available, set the current limit to
500mA.
3) With its output disabled, set the second DC power
supply to +5V. Connect the power supply to the
+5V (through an ammeter if desired) and GND1 ter-
minals on the EV kit. If available, set the current limit
to 100mA.
4) With its output disabled, set both outputs of the dual-
output DC power-supply voltages to +3V. Connect
one of the outputs to the TP1 terminal and connect
the other output to the IF_AGC terminal.
5) With its output disabled, set the RF signal generator
to a 55.25MHz frequency and a -80dBm power
level. Connect the output of the RF signal generator
to the SMA connector labeled RFIN on the evalua-
tion board.
6) Connect a 25-pin parallel cable between the PC’s
parallel port and the MAX3540 evaluation board.
7) Turn on the +3.3V VCC power supply, +5V VCC
power supply, and the +3V dual-output gain-control
power supply. The supply current from the +3.3V
VCC supply should read approximately 200mA. The
supply current from the +5V VCC supply should
read approximately 20mA. Be sure to adjust the
power supply to account for any voltage drop
across the ammeter.
8) Install and run the MAX3540 control software.
Software is available for download on the Maxim
website at www.maxim-ic.com/evkitsoftware.
9) Load the default register settings from the control
software by clicking Edit: Load Defaults.
10) Connect the SMA connector labeled IF_OUT on the
evaluation board to a spectrum analyzer or to an
oscilloscope.
11) Enable the RF signal generator’s output.
12) Set the center frequency of the RF spectrum analyz-
er to the IF frequency set on the control software.
Check the output.
Gain Adjustment Calculations
Add an additional 6dB to the voltage gain to account
for the 2:1 transformer on the output. Add another
3.96dB to the voltage gain to account for the minimum
loss pad (R11 and R10) on the input. When measuring
noise figure, account for 5.7dB power loss of the mini-
mum loss pad.
An anti-aliasing filter is provided on the IF output (C21,
C25–C29, C31, C35, L9, L11). The passband of this fil-
ter is 6MHz centered at the IF frequency of 44MHz, and
is designed for a 200Ω termination. Anti-aliasing filter
requirements vary depending on application; the filter
architecture and component values are provided as
general guidelines only.
Layout Considerations
The MAX3540 EV kit serves as a guide for PCB layout.
Keep RF signal lines as short as possible to minimize
losses and radiation. Use controlled impedance on all
high-frequency traces. The exposed pad must be sol-
dered evenly to the board’s ground plane for proper
operation. Use abundant vias beneath the exposed
pad for maximum heat dissipation. Use abundant
ground vias between RF traces to minimize undesired
coupling.
To minimize coupling between different sections of the
IC, the ideal power-supply layout is a star configuration,
which has a large decoupling capacitor at the central
VCC node. The VCC traces branch out from this node,
with each trace going to separate VCC pins of the
MAX3540. Each VCC pin must have a bypass capacitor
with a low impedance to ground at the frequency of
interest. Do not share ground vias among multiple con-
nections to the PCB ground plane.
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