Dropout regulator

today announced two new 150-mA low-noise low-dropout (LDO) regulators with the highest available current density in the small five-pin SC-70 package.

Vishay claims their 2mm by 2mm footprint makes them well suited for use in battery-powered equipment such as cell phones, PDAs, pagers, digital cameras, MP3 players, cable and DSL modems, and other noise-sensitive electronics.

Under a 150mA load condition, the SiP21101 and SiP21102 feature a low dropout of 130mV and a ground current of 110µA, helping to prolong battery life in low-voltage portable electronic systems.

Designed to maintain regulation while delivering 300-mA peak current, the new ICs both feature a fast start-up time of 50µs, making them a salient choice for systems that have a high surge current upon turn-on. Fifteen fixed output voltage options ranging from 1.2V to 5.0V are available.

The SiP21101 can be used as pin-for-pin replacement, with significantly improved current handling, for the MAX8510 and MIC5253.

An active pull-down circuit is built into the devices to clamp the output voltage when it rises beyond normal regulation, discharging it automatically by connecting the output to ground through a 100 Ohm n-channel MOSFET when the device is put in shutdown mode. This is said to provide better transient response and regulation. Reverse battery protection limits the reverse current flow to approximately 1µA to prevent damage to the IC in the event that a reversed battery is applied at the input. Short circuit and thermal protection are also built in.

The SiP21101 provides a quiet voltage source because of an external noise bypass capacitor connected to its BP pin that reduces noise to only 30µV(rms), a significant benefit for RF applications. The same pin on the SiP21102, which has a noise output of 75µV(rms), functions as an error flag output that goes low when the VOUT drops 4% below its normal voltage.

The SiP21101 and SiP21102 use ceramic capacitors or tantalum capacitors, giving designers a flexible choice of magnetic components.

Samples and production quantities are available now for most voltage options, with lead times of six-to-eight weeks for larger orders.