General Description
The MIC38C4x are fixed frequency, high performance, current-
mode PWM controllers. Micrel’s BiCMOS devices are
pin compatible with 384x bipolar devices but feature several
improvements.
Undervoltage lockout circuitry allows the ’42 and ’44 versions
to start up at 14.5V and operate down to 9V, and the ’43 and
’45 versions start at 8.4V with operation down to 7.6V. All
versions operate up to 20V.
When compared to bipolar 384x devices operating from a 15V
supply, start-up current has been reduced to 50μA typical and
operating current has been reduced to 4.0 mA typical. Decreased
output rise and fall times drive larger MOSFETs, and
rail-to-rail output capability increases efficiency, especially at
lower supply voltages. The MIC38C4x also features a trimmed
oscillator discharge current and bandgap reference.
The MIC38C4x denotes 8-pin plastic DIP and SOIC packages.
MIC384Cx-1 denotes 14-pin plastic DIP and SOIC packages.
8-pin devices feature small size, while 14-pin devices separate
the analog and power connections for improved perfomance
and power dissipation.