Wide Input Range, No R Positive-to-Negative DC/DC Controller

The LTC3704 is a wide input range, current mode, positive-to-negative DC/DC controller that drives an N-channel power MOSFET and requires very few external components. Intended for low to high power applications, it eliminates the need for a current sense resistor by utilizing the power MOSFET’s on-resistance, thereby maximizing efficiency.

The IC’s operating frequency can be set with an external resistor over a 50kHz to 1MHz range, and can be synchronized to an external clock using the MODE/SYNC pin. Burst Mode operation at light loads, a low minimum operating supply voltage of 2.5V and a low shutdown quiescent current of 10µA make the LTC3704 ideally suited for battery-operated systems.

For applications requiring constant frequency operation, the Burst Mode operation feature can be defeated using the MODE/SYNC pin. Higher than 36V switch voltage applications are possible with the LTC3704 by connecting the SENSE pin to a resistor in the source of the power MOSFET.

The LTC3704 is available in the 10-lead MSOP package.

Applications

* SLIC Power Supplies

* Telecom Power Supplies

* Portable Electronic Equipment

* Cable and DSL Modems

* Router Supplies

* High Efficiency Operation (No Sense Resistor Required)

* Wide Input Voltage Range: 2.5V to 36V

* Current Mode Control Provides Excellent Transient Response

* High Maximum Duty Cycle (Typ 92%)

* ±1% Internal Voltage Reference

* ±2% RUN Pin Threshold with 100mV Hysteresis

* Micropower Shutdown: IQ = 10µA

* Programmable Switching Frequency (50kHz to 1MHz) with One External Resistor

* Synchronizable to an External Clock Up to 1.3 × fOSC

* User-Controlled Pulse Skip or Burst Mode® Operation

* Internal 5.2V Low Dropout Voltage Regulator

* Capable of Operating with a Sense Resistor for High Output Voltage Applications (VDS >36V)

* Small 10-Lead MSOP Package