Linear Technology Corporation has unveiled a dual output, high power synchronous step-up switching DC/DC controller that replaces the boost diode with a high efficiency N-Channel MOSFET.
The device eliminates the heat sink normally required in medium to high power boost converters. The LTC3788/-1 can produce a 24 V at 5 A output with up to 97 percent efficiency, making it ideal for high power automotive audio amplifiers, industrial and medical applications where a step-up DC/DC converter must deliver high power with low heat dissipation in a small solution size.
The LTC3788/-1 operates from an input voltage ranging from 4.5 V to 38 V during start-up, maintains operation down to 2.5 V after start-up and can regulate an output voltage as high as 60 V. The powerful 1.5 Ohm onboard N-channel MOSFET gate drivers are capable of slewing large MOSFET gates quickly, minimizing transition losses and allowing for up to a 10 A per channel output current. In addition, the LTC3788/-1 draws only 125 μA when one output is active and only 200 μA when both outputs are enabled.
The constant frequency current mode architecture allows for paralleled outputs. The LTC3788 includes a clock output, phase modulation (for multiphase applications), two separate power good outputs and an adjustable current limit. The LTC3788/-1 has a phase-lockable frequency from 75 kHz to 850 kHz or a selectable fixed frequency from 50 kHz to 900 kHz. The device has adjustable cycle-by-cycle current limit protection and uses either a sense resistor or monitors the voltage drop across the inductor (DCR) for current sensing. In applications where the input voltage may sometimes exceed the regulated output voltage, the LTC3788/-1 is able to keep the synchronous MOSFET on continuously so that the output voltage follows the input voltage with minimal power loss. The LTC3788/-1 also has adjustable soft-start and maintains ±1 percent reference voltage accuracy over an operating temperature range of -40 to 125 degrees C.
Summary of Features: LTC3788/-1
- Up to 97 percent Efficiency
- Eliminates Heat Sink in Medium to High Power
- Boost Converters
- Up to 60 V VOUT Operation
- Wide VIN Ranging from 4.5 V to 38 V, Maintains Operation down to 2.5 V After Start-Up
- Powerful 1.5 Ohm Gate Drivers
- 100 percent Duty Cycle Capability for Synchronous MOSFET
- Phase Lockable Frequency from 75 kHz to 850 kHz
- Programmable Fixed Frequency from 50 kHz to 900 kHz
- RSENSE or Inductor DCR Current Sensing
- Current Mode Control
- ±1 percent Reference Voltage Accuracy over -40 to +125 degrees C
- Programmable Soft-Start
- Phase Modulation
- Power Good Outputs
Availability and Pricing
The LTC3788-1 is available in an SSOP-28 package and the LTC3788 is housed in a 32-lead 5 mm x 5 mm QFN. The 1,000-piece price starts at $4.12 each. Both versions are available from stock.