LTC3619B 400mA/800mA Synchronous Step-Down DC/DC with Average Input Current Limit FeaTuresDescripTion n Programmable Average Input Current Limit: The LTC®3619B is a dual monolithic synchronous buck ±5% Accuracy regulator using a constant frequency current mode ar- n Dual Step-Down Outputs: Up to 96% Efficiency chitecture. n Low Noise Pulse-Skipping Operation at Light Loads The input supply voltage range is 2.5V to 5.5V, making it n Input Voltage Range: 2.5V to 5.5V ideal for Li-Ion and USB powered applications. 100% duty n Output Voltage Range: 0.6V to 5V cycle capability provides low dropout operation, extend- n 2.25MHz Constant-Frequency Operation ing the run time in battery-operated systems. Low output n Power Good Output Voltage Monitor for Each Channel voltages are supported with the 0.6V feedback reference n Low Dropout Operation: 100% Duty Cycle voltage. Channel 1 and channel 2 can supply 400mA and n Independent Internal Soft-Start for Each Channel 800mA output current, respectively. n Current Mode Operation for Excellent Line and Load Transient Response The LTC3619B’s programmable average input current limit n ±2% Output Voltage Accuracy is ideal for USB applications and for point-of-load power n Short-Circuit Protected supplies because the LTC3619B’s limited input current n Shutdown Current ≤ 1μA will still allow its output to deliver high peak load currents n Available in Small Thermally Enhanced 10-Lead MS without collapsing the input supply. When the sum of and 3mm × 3mm DFN Packages both channels’ currents exceeds the input current limit, channel 2 is current limited while channel 1 remains regu- applicaTions lated. The operating frequency is internally set at 2.25MHz n allowing the use of small surface mount inductors. Internal High Peak Load Current Applications n soft-start reduces in-rush current during start-up. The USB Powered Devices n LTC3619B is available in small MSOP and 3mm × 3mm Supercapacitor Charging n DFN packages. The LTC3619B is also available in a low Radio Transmitters and Other Handheld Devices quiescent current, high efficiency Burst Mode® version, L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the LTC3619. property of their respective owners. Protected by U.S. Patents, including 5481178, 6127815, 6304066, 6498466, 6580258, 6611131. Typical applicaTionDual Monolithic Buck Regulator in 10-Lead 3mm × 3mm DFNGSM Pulse Load VIN 3.4V TO 5.5V VOUT 10µF RUN2 V 200mV/DIV IN RUN1 PGOOD2 PGOOD1 VIN AC-COUPLED 1.5µH LTC3619B VOUT2 3.3µH VOUT1 1V/DIV 3.4V AT SW2 SW1 1.8V AT 800mA 22pF 400mA IOUT 500mA/DIV 1190k VFB2 VFB1 + 2.2mF IIN RLIM GND 511k 255k 255k 10µF ×2 500mA/DIV SuperCap 1ms/DIV 3619B TA01b 3619B TA01 VIN = 5V, 500mA COMPLIANT 1000pF 116k ILOAD = 0A to 2.2A, CHANNEL 1 UNLOADED ILIM = 475mA 3619bfb 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Package Description Revision History Typical Applications Related Parts
