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APPLICATION NOTE
POWER SWITCHING REGULATOR
DESIGNING WITH THE L296 MONOLITHIC
A cost-effective replacement for costly hybrids, the L296 Power Switching Regulator delivers 4A at an output
voltage of 5.1V to 40V and includes many popular supply features. This comprehensive application guide
explains how the device operates and how it is used. Typical application circuits are also presented.
AN244/1288
The SGS THOMSON L296 is the first monolithic
switching regulator in plastic package which inclu-
des the power section. Moreover, the circuit inclu-
des all the functions which make it specially suited
for microprocessor supply.
Before the introduction of L296, which realizes the
step down configuration, this function was imple-
mented with discrete power components driven be
integrated PWM regulator circuits (giving a maxi-
mum output current of 300 to 400mA) or with hybrid
circuits. Both of these solutions are characterized by
a low efficiency of the power transistor. For this rea-
son it is generally necessary to operate at frequen-
cies in the 20kHz to 40kHz range. Of the two alter-
natives discrete solutions are usually less expensive
because they do not include as many functions as
the L296.
With the new L296 regulator the driving problem of
the power control stage has been eliminated. Besi-
des a higher overall efficiency, it is therefore also
possible to operate directly at frequencies as high as
100kHz. At 200kHz the device still operates (further
reducing the cost of the L and C external compo-
nents) when a reduction of a few percent in efficien-
cy is acceptable.
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