Datasheet LT3976 (Analog Devices)

LT3976 40V, 5A, 2MHz Step-Down Switching Regulator with 3.3µA Quiescent Current
FeaTures DescripTion
n
Ultralow Quiescent Current:
The LT®3976 is an adjustable frequency monolithic buck
3.3µA IQ at 12VIN to 3.3VOUT
switching regulator that accepts a wide input voltage range n
Low Ripple Burst Mode® Operation
up to 40V. Low quiescent current design consumes only
Output Ripple < 15mVP-P
3.3µA of supply current while regulating with no load. Low n
Wide Input Range: Operation from 4.3V to 40V
ripple Burst Mode operation maintains high efficiency at n
5A Maximum Output Current
low output currents while keeping the output ripple below n
Excellent Start-Up and Dropout Performance
15mV in a typical application. The LT3976 can supply up n
Adjustable Switching Frequency: 200kHz to 2MHz
to 5A of load current and has current limit foldback to n
Synchronizable Between 250kHz to 2MHz
limit power dissipation during short-circuit. A low dropout n Accurate Programmable Undervoltage Lockout voltage of 500mV is maintained when the input voltage n Low Shutdown Current: IQ = 700nA drops below the programmed output voltage, such as n Power Good Flag during automotive cold crank. n Soft-Start Capability An internally compensated current mode topology is used n Thermal Shutdown Protection for fast transient response and good loop stability. A high n Current Limit Foldback with Soft-Start Override efficiency 75mΩ switch is included on the die along with a n Saturating Switch Design: 75mΩ On-Resistance boost Schottky diode. An accurate 1.02V threshold enable n Small, Thermally Enhanced 16-Lead MSOP and pin can be driven directly from a microcontroller or used 24-Lead 3mm × 5mm QFN Packages as a programmable undervoltage lockout. A capacitor on the SS pin provides a controlled inrush current (soft-start).
applicaTions
A power good flag signals when VOUT reaches 91.6% of n Automotive Battery Regulation the programmed output voltage. The LT3976 is available n Portable Products in small 16-lead MSOP and 24-lead 3mm × 5mm QFN n Industrial Supplies packages with exposed pad for low thermal resistance. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Typical applicaTion No-Load Supply Current 3.3V Step-Down Converter
8 IN REGULATION VIN V 4.3V TO 40V 7 OUT = 3.3V VIN 6 OFF ON EN BOOST 0.47µF 3.3µH 5 PG SW 10µF PDS540 2Ω 4 LT3976 470pF 3 INPUT CURRENT (µA) SS OUT 2 1M VOUT RT FB 3.3V 10pF 1 10nF 5A SYNC GND 47µF 0 130k 576k 1210 0 5 10 15 20 25 30 35 40 ×2 INPUT VOLTAGE (V) 3976 TA01a f = 400kHz 3976 G05 3976f For more information www.linear.com/3976 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 Typical Applications Package Description Typical Application Related Parts