LTC1538CG-AUX
发布时间：2018/6/16
概述
The LTC1538CG-AUX are dual,synchronous step- down switching regulator controllers which drive external N-channel power MOSFETs in a phase-lockable fixed frequency architecture. The Adaptive Power TM output stage selectively drives two N-channel MOSFETs at frequencies up to 400kHz while reducing switching losses to maintain high efficiencies at low output currents. An auxiliary 0.5A linear regulator using an external PNP pass device provides a low noise, low dropout voltage source. A secondary winding feedback control pin (SFB1) guarantees regulation regardless of load on the main output by forcing continuous operation. A 5V/20mA regulator, internal 1.19V reference and an uncommitted comparator remain active when both controllers are shut down. A power-on reset timer (POR) is included which generates a signal delayed by 65536/f CLK (typ 300ms) after the controller’s output is within 5% of the regulated first voltage. Internal resistive dividers provide pin selectable output voltages with remote sense capability on one of the two outputs. The operating current levels are user-programmable via external current sense resistors. Wide input supply range allows operation from 3.5V to 30V (36V maximum).
特点
Maintains Constant Frequency at Low Output Currents
Dual N-Channel MOSFET Synchronous Drive
Programmable Fixed Frequency (PLL Lockable)
Wide VIN Range: 3.5V to 36V Operation
Ultrahigh Efficiency
Very Low Dropout Operation: 99% Duty Cycle
Low Dropout, 0.5A Linear Regulator for VPP
Generation or Low Noise Audio Supply
Built-In Power-On Reset Timer
Programmable Soft Start
Low-Battery Detector
Remote Output Voltage Sense
Foldback Current Limiting (Optional)
Pin Selectable Output Voltage
5V Standby Regulator Active in Shutdown: IQ < 200 μA
Output Voltages from 1.19V to 9V
Available in 28- and 36-Lead SSOP Packages
应用
Notebook and Palmtop Computers, PDAs
Portable Instruments
Battery-Operated Devices
DC Power Distribution Systems
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