LTC1871

Features:

 High Efficiency (No Sense Resistor Required)
 Wide Input Voltage Range: 2.5V to 36V
 Current Mode Control Provides Excellent
    Transient Response
High Maximum Duty Cycle (92% Typ)
±2% RUN Pin Threshold with 100mV Hysteresis
 ±1% Internal Voltage Reference
 Micropower Shutdown: IQ = 10µA
 Programmable Operating 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
 Output Overvoltage Protection
 Capable of Operating with a Sense Resistor for High
    Output Voltage Applications
 Small 10-Lead MSOP Package


Application

 Telecom Power Supplies
 Portable Electronic Equipment


Pinout




Specifications

VIN Voltage ...............................................  0.3V to 36V
INTV_CC Voltage ...........................................  0.3V to 7V
INTV_CC Output Current ........................................   50mA
GATE Voltage ........................... 0.3V to V_INTVCC + 0.3V
ITH, FB Voltages ....................................... 0.3V to 2.7V
RUN, MODE/SYNC Voltages .......................    0.3V to 7V
FREQ Voltage ............................................ 0.3V to 1.5V
SENSE Pin Voltage ...................................    0.3V to 36V
Operating Temperature Range (Note 2) .40°C to 85°C
Junction Temperature (Note 3) ............................   125°C
Storage Temperature Range .................65°C to 150°C
Lead Temperature (Soldering, 10 sec) ..................  300°C


Description

The LTC^® 1871 is a wide input range, current mode, boost, flyback and SEPIC controller that drives an N-channel power MOSFET and requires very few external components. Intended for low to medium 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 LTC1871 ideally suited for battery-operated systems.

For applications requiring constant frequency operation, Burst Mode operation can be defeated using the MODE/ SYNC pin. Higher output voltage boost, SEPIC and flyback applications are possible with the LTC1871 by connecting the SENSE pin to a resistor in the source of the power MOSFET.

The LTC1871 is available in the 10-lead MSOP package.