LTC1771

Features:

Very Low Standby Current: 10µA
Available in Space-Saving 8-Lead MSOP Package
High Output Currents
Wide V_INRange: 2.8V to 20V Operation
V_OUTRange: 1.23V to 18V
High Efficiency: Over 93% Possible
±2% Output Accuracy
Very Low Dropout Operation: 100% Duty Cycle
Current Mode Operation for Excellent Line and
       Load Transient Response
Defeatable Burst Mode^TMOperation
Short-Circuit Protected
Optional Programmable Soft-Start
Micropower Shutdown: I_Q= 2µA


Application

Cellular Telephones and Wireless Modems
1- to 4-Cell Lithium-Ion-Powered Applications
Portable Instruments
Battery-Powered Equipment
Battery Chargers
Scanners


Pinout

Specifications

Input Supply Voltage (V_IN)........................    0.3V to 20V
Peak Driver Output Current < 10µs (PGATE)............      1A
RUN/SS Voltage...........................      0.3V to (V_IN+ 0.3V)
MODE Voltage..........................................     0.3V to 20V
ITH, VFBVoltage..........................................    0.3V to 5V
SENSE Voltage (V_IN> 12V)...    (VIN 12V) to (VI_N+ 0.3V)
SENSE Voltage (V_IN12V)..........      0.3V to (V_IN+ 0.3V)
Junction Temperature (Note 2)............................  125°C
Operating Temperature Range (Note 3)
     LTC1771E.........................................  40°C to 85°C
     LTC1771I.........................................   40°C to 85°C
Storage Temperature Range.................65°C to 150°C
Lead Temperature (Soldering, 10 sec).................300°C


Description

The LTC^® 1771 is a high efficiency current mode stepdown DC/DC controller that draws as little as 10µA DCsupply current to regulate the output at no load while maintaining high efficiency for loads up to several amps.

The LTC1771 drives an external P-channel power MOSFET using a current mode, constant off-time architecture. An external sense resistor is used to program the operating current level. Current mode control provides short-circuit protection, excellent transient response and controlled start-up behavior. Burst Mode operation enables the LTC1771 to maintain high efficiency down to extremely low currents. Shutdown mode further reduces the supply current to a mere 2µA. For low noise applications, Burst Mode operation can be easily disabled with the MODE pin.

Wide input supply range of 2.8V to 18V (20V maximum) and 100% duty cycle operation for low dropout make the LTC1771 ideal for a wide variety of battery-powered applications where maximizing battery life is important.

The LTC1771's availability in both 8-lead MSOP and SO packages provides for a minimum area solution.