LDOs Increase Current Rating in the SC-70

Jul 27, 2005 12:20 PM

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 V_OUT 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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