Milpitas, Calif.—Linear Technology's LTC3448 low-noise, synchronous buck regulator can deliver up to 600 mA at very high efficiency over a wide load for handheld wireless applications using single cell lithium-ion, multi-cell alkaline, and NiMH sources (2.5-5.5 volt input).
When output current is greater than 3 mA, the regulator switches at a user-selectable frequency of 1.5 or 2.25 MHz. If output current drops to 3 mA or below, the chip automatically shifts to its low-dropout (linear) regulator. In this mode, the quiescent current is just 32 microamps, and less than 1 microamp in shutdown. The LTC3448's LDO mode can also be enabled via an external input. Output ripple is less than 5 mV p-p.
The LTC3448 uses internal synchronous switches with an RDS(ON) of 0.35 ohm and 0.40 ohm to deliver efficiencies as high as 96 percent at output voltages down to 0.6 volt. Users can set the LTC3448's switching frequency to either 1.5 MHz or 2.25 MHz and can synchronize the device up to 4 MHz, thus allowing the use of small, low- cost ceramic capacitors and inductors less than 1.2 mm in height.
The device's datasheet can be secured by clicking here. The LTC3448EDD is available in a 3-by-3 mm DFN-8 package; the LTC3448EMS8E is available in a thermally enhanced MSOP-8 package. Both are available from stock. Pricing starts at $2.05 each in 1k pieces.
Linear Technology, 1-800-4LINEAR, www.linear.com