Power Electronics

LDOs Increase Current Rating in the SC-70

Vishay Intertechnology has introduced two low-dropout regulators that extend the output current available from LDOs packaged in the tiny 5-pin SC-70. The devices offered in this 2-mm × 2-mm package—the SiP21101 and SiP21102—are rated at 150 mA. Target applications include battery-powered equipment such as cell phones, PDAs, pagers, digital cameras, MP3 players, cable and DSL modems, and other noise-sensitive electronics.

Under a 150-mA load condition, the SiP21101 and SiP21102 feature a dropout voltage of 130 mV and a ground current of 110 µA, helping to prolong battery life in portable systems. Designed to maintain regulation while delivering 300-mA peak current, the ICs both feature a fast start-up time of 50 µs, benefiting systems that have a high surge current upon turn-on. Fifteen fixed-output-voltage options ranging from 1.2 V to 5.0 V are available. The SiP21101 can be used as pin-for-pin replacement with for the MAX8510 and MIC5253, which are rated at 120 mA and 100 mA, respectively.

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-Ω n-channel MOSFET when the device is put in shutdown mode. This provides better transient response and regulation. Reverse battery protection limits the reverse current flow to approximately 1 µA to prevent damage to the IC under reversed-battery conditions. Short-circuit and thermal protection also are built in.

An external noise bypass capacitor connected to the SiP21101’s BP pin reduces noise to only 30 µV(rms). The same pin on the SiP21102, which has a noise output of 75 µV(rms), functions as an error flag output that goes low when the VOUT drops 4% below its normal voltage. The SiP21101 and SiP21102 use low-cost ceramic capacitors or tantalum capacitors, giving designers a flexible choice of magnetic components.

Samples and production quantities are available now for most voltage options. Unit pricing is $0.40 for 1000-piece quantities.

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