OPERATING
CONSIDERATIONS
MP240
anyparasiticresistancesRP,formedbysocketandsolderjoints
aswellasinternalamplifierlosses. Thecurrentlimitingresistor
may not be placed anywhere in the output circuit except where
shown in Figure 2. The value of the current limit resistor can
be calculated as follows: RLIM = .65/ILIMIT
SHUTDOWN
The output stage is turned off by applying a 5V level to HSD
(pin 8) relative to LSD (pin 7). This is a non-latching circuit. As
long as HSD remains high relative to LSD the output stage will
be turned off. LSD will normally be tied to signal ground but
LSD may float from -VB to +VB - 10V. Shutdown can be used
to lower quiescent current for standby operation or as part of
a load protection circuit.
BOOST OPERATION
Withtheboostfeaturethesmallsignalstagesoftheamplifier
are operated at a higher supply voltages than the amplifier’s
high current output stage. +VB (pin 1) and -VB (pin 38) are con-
nectedtothesmallsignalstages. Anadditional10Vonthe+VB
and -VB pin is sufficient to allow the small signal stages to drive
the output stage into the triode region and improve the output
voltageswingforextraefficientoperationwhenrequired. When
the boost feature is not needed +VS and -VS are connected to
+VB and -VB respectively. +VB and -VB must not be operated
at supply voltages less than +VS and -VS respectively.
BIAS CLASS OPTION
Normally pin 5 (Iq) is left open. But when pin 5 is connected
to pin 6 (Cc1) the quiescent current in the output stage is dis-
abled. This results in lower quiescent power, but also class
C operation of the output stage and the resulting crossover
distortion. In many applications, such as driving motors, the
distortion may be unimportant and lower standby power dis-
sipation is an advantage.
This data sheet has been carefully checked and is believed to be reliable, however, no responsibility is assumed for possible inaccuracies or omissions. All specifications are subject to change without notice.
APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
MP240U REV F JANUARY 2006
© 2006 Apex Microtechnology Corp.
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