LTC3619 400mA/800mA Synchronous Step-Down DC/DC with Average Input Current Limit FeaTuresDescripTion n Programmable Average Input Current Limit: The LTC®3619 is a dual monolithic synchronous buck ±5% Accuracy regulator using a constant frequency, current mode n Dual Step-Down Outputs: Up to 96% Efficiency architecture. n Low Ripple (<25mVP-P) Burst Mode ® Operation: The input supply voltage range is 2.5V to 5.5V, making it IQ = 50µA ideal for Li-Ion and USB powered applications. 100% duty n Input Voltage Range: 2.5V to 5.5V cycle capability provides low dropout operation, extend- n Output Voltage Range: 0.6V to 5V ing the run time in battery-operated systems. Low output n 2.25MHz Constant-Frequency Operation voltages are supported with the 0.6V feedback reference n Power Good Output Voltage Monitor for Each Channel voltage. Channel 1 and channel 2 can supply 400mA and n Low Dropout Operation: 100% Duty Cycle 800mA output current, respectively. n Independent Internal Soft-Start for Each Channel n The LTC3619’s programmable average input current limit Current Mode Operation for Excellent Line and Load is ideal for USB applications and for point-of-load power Transient Response n supplies because the LTC3619’s limited input current will ±2% Output Voltage Accuracy n still allow its output to deliver high peak load currents Short-Circuit Protected n without collapsing the input supply. When the sum of both Shutdown Current ≤ 1μA n channels’ currents exceeds the input current limit, channel 2 Available in Small Thermally Enhanced 10-Lead MSE is current limited while channel 1 remains regulated. The and 3mm × 3mm DFN Packages operating frequency is internally set at 2.25MHz allowing the use of small surface mount inductors. Internal soft-start applicaTions reduces in-rush current during start-up. The LTC3619 is n available in small MSOP and 3mm High Peak Load Current Applications × 3mm DFN packages n and is also available in a low noise, high efficiency pulse- USB Powered Devices n skipping version, LTC3619B. Supercapacitor Charging n L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks Radio Transmitters and Other Handheld Devices and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the 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 VOUT2 200mV/DIV 10µF RUN2 VIN RUN1 VIN PGOOD2 PGOOD1 1V/DIV AC-COUPLED 1.5µH LTC3619 VOUT2 3.3µH VOUT1 3.4V AT SW2 SW1 1.8V AT 800mA 22pF 400mA IOUT 500mA/DIV 1190k VFB2 VFB1 + IIN 2.2mF RLIM GND 511k 255k 255k 10µF 500mA/DIV ×2 3619 TA01b SuperCap 3619 TA01a 1ms/DIV 1000pF 116k VIN = 5V, 500mA COMPLIANT, ILOAD = 0A TO 2.2A, CHANNEL 1 UNLOADED ILIM = 475mA 3619fa 1 Document Outline Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Functional Diagram Operation Applications Information Package Description Typical Application Related Parts
