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 Fast 20ns output rise and 15ns output fall times PWM controllers with 1A drive current capability. Micrels 40C to +85C temperature range BiCMOS devices are pin-compatible with 384x bipolar de- exceeds UC284x specifications vices. Their high output drive, with fast rise and fall times, High-performance, low-power BiCMOS Process combined with low startup current make it an ideal PWM Ultralow start-up current (50A typical) controller where high efficiency is required. Low operating current (4mA typical) High output drive (1A peak current, HC version) Undervoltage lockout circuitry allows the 42 and 44 versions CMOS outputs with rail-to-rail swing to start up at 14.5V and operate down to 9V, and the 43 and Current-mode operation up to 500kHz 45 versions start at 8.4V with operation down to 7.6V. All Trimmed 5V bandgap reference versions operate up to 20V. Pin-for-pin compatible with UC3842/3843/3844/3845(A) When compared to bipolar UC384x devices operating from a Trimmed oscillator discharge current 15V supply, start-up current has been reduced to 50A UVLO with hysteresis typical and operating current has been reduced to 4.0 mA Low cross-conduction currents typical. Decreased output rise and fall times drive larger MOSFETs, and rail-to-rail output capability increases effi- Applications ciency, especially at lower supply voltages. The MIC38HC4x also features a trimmed oscillator discharge current and Current-mode, off-line, switched-mode power supplies bandgap reference. Current-mode, dc-to-dc converters. MIC38HC4x-1 is available in 14-pin plastic DIP and SOIC Step-down buck regulators packages. 8-pin devices feature small size, while 14-pin Step-up boost regulators devices separate the analog and power connections for Flyback, isolated regulators improved performance and power dissipation. Forward converters Synchronous FET converters Functional Diagram * VDD 7 (12) 35V 5V UVLO VREF (VD) Reference 8 (14) (11) Oscillator RT/CT OUT 4 (7) 6 (10) TQ FB 2R 2 (3) (PGND) S (8) Q 2.5V R R * COMP GND*(AGND) ISNS 1 (1) 5 (9) 3 (5) ( ) pins are on MIC38HC4x-1 (14-lead) versions only * MIC38HC4x (8-lead) versions only MIC38HC42, MIC38HC43 (96% max. duty cycle) versions only MIC38HC44, MIC38HC45 (50% max. duty cycle) versions only Micrel, Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 MIC38HC42/3/4/5 Micrel, Inc. Ordering Information Part Number Junction Standard Pb-Free Temp. Range Package MIC38HC42BN MIC38HC42YN 40C to +85C 8-pin Plastic DIP MIC38HC43BN MIC38HC43YN 40C to +85C 8-pin Plastic DIP MIC38HC44BN MIC38HC44YN 40C to +85C 8-pin Plastic DIP MIC38HC45BN MIC38HC45YN 40C to +85C 8-pin Plastic DIP MIC38HC42-1BN Contact Factory 40C to +85C 14-pin Plastic DIP MIC38HC43-1BN Contact Factory 40C to +85C 14-pin Plastic DIP MIC38HC44-1BN Contact Factory 40C to +85C 14-pin Plastic DIP MIC38HC45-1BN Contact Factory 40C to +85C 14-pin Plastic DIP MIC38HC42BM MIC38HC42YM 40C to +85C 8-pin SOIC MIC38HC43BM MIC38HC43YM 40C to +85C 8-pin SOIC MIC38HC44BM MIC38HC44YM 40C to +85C 8-pin SOIC MIC38HC45BM MIC38HC45YM 40C to +85C 8-pin SOIC MIC38HC42-1BM MIC38HC42-1YM 40C to +85C 14-pin SOIC MIC38HC43-1BM MIC38HC43-1YM 40C to +85C 14-pin SOIC MIC38HC44-1BM MIC38HC44-1YM 40C to +85C 14-pin SOIC MIC38HC45-1BM MIC38HC45-1YM 40C to +85C 14-pin SOIC Selection Guide UVLO Thresholds Startup 8.4V Startup 14.5V Duty Cycle Minimum Operating 7.6V Minimum Operating 9V 0% to 96% MIC38HC43 MIC38HC42 0% to 50% MIC38HC45 MIC38HC44 M9999-042205 2 April 2005