The Bay Linear B3842/43/44/45 are fixed frequency currentmode PWM controller. These devices are designed for OffLine and DC-to-DC converter applications with minimum external components. The B3842 family Feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totempole output. Ideally suited for driving a power N-Channel MOSFET's. It is low when is on off stage. Protection circuitry includes built in under-voltage lockout and current limiting. Major differences between members of these series are the UVLO thresholds and maximum duty-cycle ranges. Typical UVLO thresholds of 16V (on) and 10V (off) on the B3842 and B3844 devices make them ideally suited to off-line applications. These corresponding typical thresholds for the B3842 and B3845 devcies are 8.4V (on) and 7.6V (off). The B3842 and B3843 devcies can operate to duty cycles approaching 100%. A duty-Cycle range of 0 to 50% is obtained by the B3844 and B3845 by the addition of an internal toggle flip-flop, which blanks the output off every other clock cycle. It id available in 8 pin DIP and SOIC packages.