LTC3409A - 600mA Low VIN Buck Regulator in 3mm × 3mm DFN

The LTC3409A is a high efficiency, monolithic synchronous buck regulator using a constant frequency, current mode architecture. The LTC3409A improves upon the LTC3409’s light load regulation in Burst Mode operation. The output voltage is adjusted via an external resistor divider. Fixed switching frequencies of 1.7MHz and 2.6MHz are supported. Alternatively, an internal PLL will synchronize to an external clock in the frequency range of 1MHz to 3MHz. This range of switching frequencies allows the use of small surface mount inductors and capacitors, including ceramics. Supply current during Burst Mode operation is only 65μA dropping to <1μA in shutdown. The 1.6V to 5.5V input voltage range makes the LTC3409A ideally suited for single cell Li-Ion, Li-Metal and 2-cell alkaline, NiCd or NiMH battery-powered applications. 100% duty cycle capability provides low dropout operation, extending battery life in portable systems. Burst Mode operation can be user-enabled, increasing efficiency at light loads, further extending battery life. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Internal soft-start offers controlled output voltage rise time at startup without the need for external components.

Features

1.6V to 5.5V Input Voltage Range
0.62V to 5.5V Output Voltage Range
Internal Soft-Start
Selectable 1.7MHz or 2.6MHz Constant Frequency Operation
Internal Oscillator Can Be Synchronized to an External Clock, 1MHz to 3MHz Range
High Efficiency: Up to 95%
65μA Quiescent Current, Burst Mode® Operation
600mA Output Current (VIN = 1.8V, VOUT = 1.2V)
750mA Peak Inductor Current
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
0.612V Reference Voltage
Stable with Ceramic Capacitors
Shutdown Mode Draws <1μA Supply Current
Current Mode Operation for Excellent Line and Load Transient Response
Overtemperature Protection
Available in a Low Profile (0.75mm)
8-Lead (3mm × 3mm) DFN Package