Date: 22/01/2009

32V Synchronous buck regulator deliver 6 Amps from a 7mm x 8mm QFN

The LTC3609 from Linear Technology is a high efficiency, synchronous buck regulator that can deliver up to 6A of continuous output current at voltages as low as 0.6V. It operates from an input voltage range of 4V to 32V (36V ABS Max), making it ideal for applications with multicell Li-Ion, lead acid batteries or fixed input voltage rails up to 32V. Its valley current control architecture delivers very low duty cycle operation at high frequencies with excellent transient response. The operating frequency is set by an external resistor. With a switching frequency of up to 1MHz, the LTC3609 can utilize small, low cost ceramic capacitors and low profile inductors.

The LTC3609 uses internal switches with an RDS(ON) of only 18mOhms and 13mOhms to deliver efficiencies as high as 95%. It can also be configured for discontinuous or forced continuous operation. Forced continuous operation reduces noise and RF interference while discontinuous mode provides high efficiency by reducing switching losses at light loads, requiring only 900uA of quiescent current. Shutdown quiescent current is only 15uA. Additional features include a Power Good voltage monitor, adjustable current limit, output overvoltage protection and programmable soft-start.

The LTC3609EWKG is available from stock in a 52-lead, 7mm x 8mm QFN package. Pricing starts at $7.75 each in 1,000-piece quantities. An industrial grade version, the LTC3609IWKG, is tested and guaranteed to operate from a -40°C to 125°C operating junction temperature and is priced at $9.12 each in 1,000-piece quantities. All versions are available from stock. For more information, visit www.linear.com.

Summary of Features:

6A Output Current
Wide VIN Range = 4V to 32V (36V Maximum)
Internal N-Channel MOSFETs
True Current Mode Control
Optimized for High Step-Down Ratios
tON(MIN) ? 100ns
Extremely Fast Transient Response
Stable with Ceramic COUT
±1% 0.6V Voltage Reference
Power Good Output Voltage Monitor
Adjustable On-Time/Switching Frequency
Adjustable Current Limit
Programmable Soft-Start
Output Overvoltage Protection
Optional Short-Circuit Shutdown Timer
Low Shutdown IQ: 15uA
Available in a 7mm × 8mm 52-Pin QFN Package