Datasheet LTC1871X (Analog Devices)

LTC1871X Wide Input Range, No RSENSE™ Current Mode Boost, Flyback and SEPIC Controller
FEATURES DESCRIPTION
n
High Efficiency (No Sense Resistor Required)
LTC®1871X is a wide input range, current mode, boost, n
Wide Input Voltage Range: 2.5V to 36V
flyback or SEPIC controller that drives an N-channel power n
Current Mode Control Provides Excellent Transient
MOSFET. LTC1871X is rated to 175°C junction tempera-
Response
ture and is 100% tested at 175°C. Intended for low to n
High Maximum Duty Cycle (92% Typ)
medium power applications, it eliminates the need for a n
±2% RUN Pin Threshold with 100mV Hysteresis
current sense resistor by utilizing the power MOSFET’s n
±2% Internal Voltage Reference
on-resistance, thereby maximizing efficiency. n Micropower Shutdown: IQ = 10μA The IC’s operating frequency can be set with an external n Programmable Operating Frequency (65kHz to resistor over a 65kHz to 900kHz range, and can be syn- 900kHz) with One External Resistor chronized to an external clock using the MODE/SYNC n Synchronizable to an External Clock Up to 1.3 × fOSC pin. Burst Mode operation at light loads, a low minimum n User-Controlled Pulse Skip or Burst Mode® Operation operating supply voltage of 2.5V and a low shutdown n Internal 5.2V Low Dropout Voltage Regulator quiescent current of 10μA make the LTC1871X ideally n Output Overvoltage Protection suited for battery-operated systems. n Capable of Operating with a Sense Resistor for High Output Voltage Applications For applications requiring constant frequency operation, n Small 10-Lead MSOP Package Burst Mode operation can be defeated using the MODE/ SYNC pin. Higher output voltage boost, SEPIC and flyback applications are possible with the LTC1871X by connect-
APPLICATIONS
ing the SENSE pin to a resistor in the source of the power n Telecom Power Supplies MOSFET. The LTC1871X is available in the 10-lead MSOP n Portable Electronic Equipment package. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION FB Voltage vs Temperature
VIN 1.250 5V 100µF 6.3V 10µH 1.245 1.240 RUN SENSE V LTC1871X OUT ITH VIN 12V 1.235 2A INTVCC GATE 110k TAGE (V) 1.230 33.2k MODE/SYNC FB 47µF 25V 1.225 4.7µF FREQ FB VOL ×8 10nF 80.6k GND 12.4k 1.220 GND 1.215 1871x F01 1.210
Figure 1. High Efficiency 5V Input, 12V Output Boost Converter (Bootstrapped)
–50 –25 0 25 50 75 100 125 150 175 200 TEMPERATURE (°C) 1871x F01b 1871xf For more information www.linear.com/LTC1871X 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Application Related Parts