LX1792 E
VALUATION
B
OARD
U
SER
G
UIDE
Copyright © 2002
Microsemi
Page 5
Rev 0.2, 3/4/2002
Integrated Products – Power Management
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Q
UICK
S
TART
G
UIDE
The LX1792 Evaluation Board is a fully
functional, Class-D Amplifier. To begin evaluation
of the LX1792, just follow these simple steps.
1) Visually inspect the board to make sure
that components were not damaged during
shipping.
2) Power and Ground Connections The
power and ground connections are made
through banana jacks J3 and J4. Connect
the positive terminal of the power supply
or battery to J3, which is labeled "VDD".
Connect the negative terminal of the
supply or battery to J4, which is labeled
"VSS". Make sure the correct connections
are made before turning on power supply.
3) Input
Connection
To input a function generator signal,
connect source to jack J1, labeled "BNC
IN". To input an audio signal, connect
source to jack J2, labeled "RCA IN".
4) Input
Selection
If using the BNC jack, set Input Select
switch SW1 to the "BNC" position. If
using the RCA jack, set SW1 to the
"RCA" position.
5) Gain
Set
Choose the gain by selecting the external
resistors (R1>25Kohms). Gain = 10dB +
20log(R2/R1)
6)
Output Impedance Selection
For most Evaluation Board applications,
the Impedance Select switch SW2 should
be set to 10
Ω
. The other impedance
settings reduce current consumption with
the tradeoff of increasing switch output
impedance.
7) Output
Select
The "Headphone" setting will directly
connect the differential output of the
amplifier to the headphone jack. The
"Single-Ended" setting will connect the
differential amplifier output to a
transformer and convert it to a single-
ended signal. The single-ended signal is
then low-pass filtered with a cutoff
frequency of 20kHz. The output of the
low-pass filter is connected to BNC jack
J5. The "Unloaded" setting will
disconnect the amplifier from either load.
8) Output
Connection
To listen to the output of the amplifier,
connect headphones to J7, labeled
"Headphone OUT", and verify that the
Output Select is set to "Headphone".
Headphones with a minimum impedance
of 150
Ω
should be used. To view the
amplifier output on either a spectrum
analyzer or an oscilloscope, connect to
BNC connector J5, labeled "Single-Ended
OUT", and verify SW4 is set to "Single-
Ended".
9) Breadboard
The differential output signal is directly
available on the breadboard. The positive
output is labeled "OUTP", and the
negative output is labeled "OUTN". The
power supply ground is also available on
the breadboard, and is labeled "GND".
BNC connector J6 is provided to access
the breadboard output, which is labeled
"BREADBOARD OUT". The positive
output pin of J6 is wired to the breadboard,
and is labeled "BB OUT". When using the
breadboard, make sure the Output Select
switch is set to "Unloaded".
10) Power
Source
If using a power supply, verify that it is set
to 1.25V before connecting it to the
Evaluation Board. A "C" (1.5V) battery
can also be used.
11) Signal Generator Source
Set the signal generator to the appropriate
level for best results (see examples in table
below).
Obsolete
