Abstract: A low dropout linear regulator utilizing a vertical PNP transistor as its pass element, integrated with CMOS circuitry. The vertical PNP transistor includes a P-well formed in a lightly doped N type substrate for its collector. An N-type region formed in the P-well is its base and a P-type region formed in the N-type region is its emitter. The emitter receives a variable input supply and the collector provides a regulated output signal to the load being driven. As the input voltage diminishes to less than a diode drop above the output voltage, the vertical PNP transistor tries to saturate and its associated parasitic NPN transistor turns on. To limit the effects of the parasitic NPN transistor and maintain a regulated output, a current limiter is connected between the input and the collector of the NPN parasitic transistor.

Abstract: A voltage regulator is capable of providing multiple fixed outputs plus a user-selected output by the use of a window comparator circuit that produces one of three different possible outputs, depending upon whether an input control signal is above, below or within the window voltage range. Two of the outputs operate different switches within a feedback circuit for a multiplying operational amplifier, causing the amplifier to produce different regulated output levels depending upon which switch is operated. The third window output disables the operational amplifier and establishes a mode in which the regulated output is set by an external feedback circuit for another operational amplifier, with the external circuit connected across the circuit's input and output terminals.

Abstract: A voltage reference circuit design which is temperature compensated to the second order is presented. The circuit comprises a sub-circuit for generating a bandgap voltage reference temperature compensated to the first order and a sub-circuit having a differential amplifier for generating a current having a second order temperature dependency. The current in turn is used for generating a correction voltage having a second order temperature dependency. The first order band gap voltage reference and the correction voltage are combined to provide the second order temperature compensated band gap voltage reference.