CURRENT MODE PWM CONTROLLER
The CM3842/43 are fixed frequency current-mode PWM !
controllers specially designed for OFF-Line switching !
power supply and DC-to-DC converters with a minimum !
number of external components. These devices feature !
a trimmed oscillator for precise duty cycle control, a !
temperature compensated reference, high gain error !
amplifier, current sensing comparator, and high current !
totem pole output which is suitable for driving !
The under voltage lock-out (U.V.L.O.) is designed to
operated with 200µA typ. start-up current, allowing an
efficient bootstrap supply voltage design. The U.V.L.O.
thresholds for the CM3842 are 16V (on) and 10V (off)
which are ideal for off-line applications. The
corresponding typical threshold for the CM3843 are
8.4V (on) and 7.6V (off). The CM3842/43 can operated
within 100% duty cycle.
Low Start-Up current ( typ. 200µA)
Optimized for Off-Line and DC-to-DC Converters
Maximum Duty Cycle
U.V.L.O. with Hysteresis
Operating Frequency Up to 500KHz
Internal Trimmed Bandgap Reference
High Current Totem Pole Output
Error Amplifier With Low Output Resistance
Available in 8-Pin Plastic DIP and Surface Mount
! Off-line flyback or forward converters.
! DC-to-DC buck or boost converter.
! Monitor Power Supply
Hysteresis Max. Duty Cycle
Champion Microelectronic Corporation