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Operation Manual
Micro-Tech Series Power Amplifiers
page 18
To further protect the output stages, the pat-
ented ODEP circuitry is used. It produces an
analog output proportional to the always
changing die temperature of the output transis-
tor. This output controls the translator stage
previously mentioned, removing any further
drive that may exceed the safe operating area of
the output stage.
Thermal sensors S100 and S200 give the
ODEP circuits vital information on the operat-
ing temperature of the heat sink on which the
output devices are mounted.
Should the amplifier fail in a way that would
cause DC across the output lead, the DC pro-
tection circuit senses this on the negative feed-
back loop and shuts down the output stage
drive until the DC is removed.
6.2.2 Bridge-Mono Operation
By setting the back panel stereo/mono switch
to Bridge-Mono, you can convert a Micro-Tech
amplifier for bridged-mono operation. With a
signal applied to the channel 1 input and the
load connected between the positive (+) output
terminals, twice the voltage can be delivered to
the load.
The channel 1 output feeds the channel 2 error
amp U204-A. The signal feeding channel 2 is
inverted so the channel 2 output will have the
opposite polarity of channel 1. This makes it
possible to deliver twice as much voltage to the
load while the protection mechanisms for each
channel continue to work independently.
6.2.3 Parallel-Mono Operation
With the stereo/mono switch set to Parallel-
Mono, the output of channel 2 is paralleled with
that of channel 1. A suitable jumper capable of
handling high current must be connected
across the positive (+) output terminals to gain
the benefits of this operating mode.
The signal path for channel 1 is the same as
previously discussed, except that channel 1
also drives the output stage of channel 2. The
balanced input, error amp, translators, and
LVAs of channel 2 are disconnected and no
longer control the channel 2 output stage. The
channel 2 output stage and protection mecha-
nisms are also coupled through S1 and func-
tion as one.
In Parallel-Mono mode, the amplifier can
deliver twice the current of a single channel.
Because the channel 2 ODEP circuit is coupled
through S1, the amplifier gains additional pro-
tection if a fault occurs in the channel 2 output
stage. The channel 2 ODEP circuit will limit the
output of both output stages by removing the
drive from the channel 1 voltage translator.
6 Principles of Operation