Hot-selling and scarce UC1842J Current Mode PWM Controller IC DIP8 spot stock

Product Descriptions

The UC1842/3/4/5 family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count.  Internally implemented circuits include under-voltage lockout featuring start up current less than  1mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N Channel MOSFETs, is low in the off state.

Differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle ranges. The UC1842 and UC1844 have UVLO  thresholds  of  16V  (on)  and  10V  (off),  ideally  suited  to  off-line applications. The corresponding thresholds for the UC1843 and UC1845 are8.4V  and  7 .6V.  The  UC1842  and  UC1843  can  operate  to  duty  cycles approaching 100%. A range of zero to 50% is obtained by the UC1844 and UC1845 by the addition of an internal toggle flip flop which blanks the output off every other clock cycle.

Product Features

•     Optimized For Off-line And DC To DC Converters

•     Low Start Up Current  (<1mA)

•     Automatic Feed Forward Compensation

•     Pulse-by-pulse Current Limiting

•     Enhanced Load Response Characteristics

•     Under-voltage Lockout With Hysteresis

•     Double Pulse Suppression

•     High Current Totem Pole Output

•     Internally Trimmed Bandgap Reference

•     500khz Operation

•     Low RO Error Amp

Product Photos

For more product information, please download the PDF

WhenCE is HIGH (deselected),the device assumes a standby mode at which the power dissipation can be reduced down to250 µW (typical) with CMOS input levels.