UC2833

UC1832/3 UC2832/3 UC3832/3 Precision Low Dropout Linear Controllers FEATURES Precision 1% Reference Over-Current Sense Threshold Accurate to 5% Programmable Duty-Ratio Over-Current Protection 4.5V to 36V Operation 100mA Output Drive, Source or Sink Under-Voltage Lockout DESCRIPTION The UC1832 and UC1833 series of precision linear regulators include all the control functions required in the design of very low dropout linear regulators. Additionally, they feature an innovative duty-ratio current limiting technique which provides peak load capability while limiting the average power dissipation of the external pass transistor during fault conditions. When the load current reaches an accurately programmed threshold, a gated-astable timer is enabled, which switches the regulator’s pass device off and on at an externally programmable duty-ratio. During the on-time of the pass element, the output current is limited to a value slightly higher than the trip threshold of the duty-ratio timer. The constant-current-limit is programmable on the UCx832 to allow higher peak current during the on-time of the pass device. With duty-ratio control, high initial load demands and short circuit protection may both be accommodated without extra heat sinking or foldback current limiting. Additionally, if the timer pin is grounded, the duty-ratio timer is disabled, and the IC operates in constant-voltage/constant-current regulating mode. These IC’s include a 2 Volt (±1%) reference, erro...