Low Voltage Drop Regulators

The fast spreading incorpor- ation of CMOS, HC and HCT chips has created a need for voltage regulators with a very low internal drop to enable powering CMOS-based equip- ment from a set of batteries delivering 6 V. The recently introduced Types LP2951 and LP2950 from National Semicon- ductor are micropower voltage regulators with a variable out- put voltage of 1.24-29 V and a fixed output voltage of 5 V, respectively. The former features an internal voltage div- ider with a 5 V tap bonded out to a pin, a logic compatible shutdown input, and an open- collector ERROR output which warns of a low output voltage, often due to an insufficient bat- tery voltage at the input. The ERROR output is extremely useful for an early warning system that arranges for a R2 microprocessor to be reset LP 2951 LP 2950 ERROR O properly before the supply voltage falls to a level that would upset the operation of the system it controls. The voltage drop across the LP2951 is only 0.4 V at a load current of...