MIC38HC42/3/4/5 Micrel, Inc. MIC38HC42/3/4/5
BiCMOS 1A Current-Mode PWM Controllers General Description Features The MIC38HC4x family are fixed frequency current-mode
PWM controllers with 1A drive current capability. Micrel’s
BiCMOS devices are pin-compatible with 384x bipolar devices. Their high output drive, with fast rise and fall times,
combined with low startup current make it an ideal PWM
controller where high efficiency is required.
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 UC384x devices operating from a
15V supply, start-up current has been reduced to 50ВµA
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 MIC38HC4x
also features a trimmed oscillator discharge current and
bandgap reference.
MIC38HC4x-1 is available in 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 performance and power dissipation. Fast 20ns output rise and 15ns output fall times –40°C to +85°C temperature range
exceeds UC284x specifications High-performance, low-power BiCMOS Process Ultralow start-up current (50ВµA typical) Low operating current (4mA typical) High output drive (1A peak current, HC version) CMOS outputs with rail-to-rail swing Current-mode operation up to 500kHz Trimmed 5V bandgap reference Pin-for-pin compatible with UC3842/3843/3844/3845(A) Trimmed oscillator discharge current UVLO with hysteresis Low cross-conduction currents Applications Current-mode, off-line, switched-mode power supplies
Current-mode, dc-to-dc converters. …