特点
High Efficiency: Up to 95%
No Current Sense Resistor Required
Constant Frequency 530kHz Operation Allows Small Size, Surface Mount Inductors
OPTI-LOOP
?
Compensation Minimizes COUT
Selectable Burst Mode
?
Operation
Minimum Start-Up Voltage as Low as 0.9V
Synchronizable Between 400kHz and 750kHz
Micropower Shutdown: 10μA
Current Mode Operation for Excellent Line and Load Transient Response
Soft-Start Reduces Supply Current Transients
1.5% Output Voltage Accuracy
Uses Low Value, Small Size, Surface Mount Inductors
Available in 10-Lead MSOP Package
典型应用
典型应用
描述
The LTC ? 1700 is a current mode synchronous step-up DC/DC controller that drives external N-channel and P-channel power MOSFETs using a constant frequency PWM architecture. Current limiting is provided by sensing the voltage drop across the main MOSFET, eliminating the need of a sense resistor. This No RSENSE TM technique helps the LTC1700 maintain high efficiency at heavy loads while Burst Mode operation ensures high efficiency at light loads, thus providing high efficiencies over a wide range of load currents.
The LTC1700 operates at a minimum input voltage as low as 0.9V. The device boasts a ±1.5% output voltage accuracy and consumes only 200μA of quiescent current. In shutdown, it only draws 10μA.
To prevent inductor current runaway, the duty cycle is limited to 90%. Overvoltage protection is also provided which shuts both the external MOSFETs off when tripped.
High constant operating frequency of 530kHz allows the use of small inductors and output capacitors. The LTC1700 can also be synchronized between 400kHz to 750kHz. Burst Mode operation is inhibited when the device is externally clocked or when the SYNC/MODE pin is pulled low to reduce noise and RF interference.