Datasheet LT3971, LT3971-3.3, LT3971-5 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 38V, 1.2A, 2MHz Step-Down Regulator with 2.8μA Quiescent Current |
| Pages / Page | 28 / 1 — FEATURES. DESCRIPTION. Ultralow Quiescent Current:. 2.8µA IQ Regulating … |
| File Format / Size | PDF / 643 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Ultralow Quiescent Current:. 2.8µA IQ Regulating 12VIN to 3.3VOUT. Fixed Output Voltages: 3.3V, 5V,
Model Line for this Datasheet
- LT3971EDD#PBF LT3971EDD#TRPBF LT3971EDD-3.3#PBF LT3971EDD-3.3#TRPBF LT3971EDD-5#PBF LT3971EDD-5#TRPBF LT3971EMSE#PBF LT3971EMSE#TRPBF LT3971EMSE-3.3#PBF LT3971EMSE-3.3#TRPBF LT3971EMSE-5#PBF LT3971EMSE-5#TRPBF LT3971EMSE16#PBF LT3971EMSE16#TRPBF LT3971IDD#PBF LT3971IDD#TRPBF LT3971IDD-3.3#PBF LT3971IDD-3.3#TRPBF LT3971IDD-5#PBF LT3971IDD-5#TRPBF LT3971IMSE#PBF LT3971IMSE#TRPBF LT3971IMSE-3.3#PBF LT3971IMSE-3.3#TRPBF LT3971IMSE-5#PBF LT3971IMSE-5#TRPBF LT3971IMSE16#PBF LT3971IMSE16#TRPBF
Text Version of Document
LT3971/LT3971-3.3/LT3971-5 38V, 1.2A, 2MHz Step-Down Regulator with 2.8µA Quiescent Current
FEATURES DESCRIPTION
n
Ultralow Quiescent Current:
The LT®3971 is an adjustable frequency monolithic buck
2.8µA IQ Regulating 12VIN to 3.3VOUT
switching regulator that accepts a wide input voltage range n
Fixed Output Voltages: 3.3V, 5V,
up to 38V. Low quiescent current design consumes only
2.1µA IQ Regulating 12VIN to 3.3VOUT
2.8µA of supply current while regulating with no load. Low n
Low Ripple Burst Mode
®
Operation:
ripple Burst Mode operation maintains high efficiency at
Output Ripple < 15mVP-P
low output currents while keeping the output ripple below n
Wide Input Voltage Range: 4.3V to 38V
15mV in a typical application. An internally compensated n
1.2A Maximum Output Current
current mode topology is used for fast transient response n
Adjustable Switching Frequency: 200kHz to 2MHz
and good loop stability. A high efficiency 0.33Ω switch n
Synchronizable Between 250kHz to 2MHz
is included on the die along with a boost Schottky diode n
Fast Transient Response
and the necessary oscillator, control and logic circuitry. n Accurate 1V Enable Pin Threshold An accurate 1V threshold enable pin can be used to shut n Low Shutdown Current: IQ = 700nA down the LT3971, reducing the input supply current to n Power Good Flag 700nA. A capacitor on the SS pin provides a controlled n Soft-Start Capability inrush current (soft-start). A power good flag signals n Internal Compensation when VOUT reaches 91% of the programmed output volt- n Output Voltage: 1.19V to 30V age. The LT3971 is available in small 10-lead MSOP and n Small Thermally Enhanced 10-Lead MSOP, 16-Lead 3mm × 3mm DFN packages with exposed pads for low MSOP and (3mm × 3mm) DFN Packages thermal resistance. A 16-lead MSOP is also offered which has enhanced pin-to-pin fault tolerance.
APPLICATIONS
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. n Automotive Battery Regulation n Power for Portable Products n Industrial Supplies
TYPICAL APPLICATION No Load Supply Current 3.3V Step Down Converter
3.0 VIN OUTPUT IN REGULATION 4.5V TO 38V VIN OFF ON EN BOOST 2.5 LT3971-5 0.47µF 4.7µH PG SW SS 4.7µF LT3971-3.3 2.0 RT LT3971-3.3 BD VOUT INPUT CURRENT (µA) 1.5 49.9k VOUT 3.3V SYNC GND 1.2A 22µF f = 800kHz 1.0 3971 TA01 5 10 15 20 25 30 35 INPUT VOLTAGE (V) 3971 TA01b 3971fd 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 Revision History Related Parts
FEATURES DESCRIPTION
n
Ultralow Quiescent Current:
The LT®3971 is an adjustable frequency monolithic buck
2.8µA IQ Regulating 12VIN to 3.3VOUT
switching regulator that accepts a wide input voltage range n
Fixed Output Voltages: 3.3V, 5V,
up to 38V. Low quiescent current design consumes only
2.1µA IQ Regulating 12VIN to 3.3VOUT
2.8µA of supply current while regulating with no load. Low n
Low Ripple Burst Mode
®
Operation:
ripple Burst Mode operation maintains high efficiency at
Output Ripple < 15mVP-P
low output currents while keeping the output ripple below n
Wide Input Voltage Range: 4.3V to 38V
15mV in a typical application. An internally compensated n
1.2A Maximum Output Current
current mode topology is used for fast transient response n
Adjustable Switching Frequency: 200kHz to 2MHz
and good loop stability. A high efficiency 0.33Ω switch n
Synchronizable Between 250kHz to 2MHz
is included on the die along with a boost Schottky diode n
Fast Transient Response
and the necessary oscillator, control and logic circuitry. n Accurate 1V Enable Pin Threshold An accurate 1V threshold enable pin can be used to shut n Low Shutdown Current: IQ = 700nA down the LT3971, reducing the input supply current to n Power Good Flag 700nA. A capacitor on the SS pin provides a controlled n Soft-Start Capability inrush current (soft-start). A power good flag signals n Internal Compensation when VOUT reaches 91% of the programmed output volt- n Output Voltage: 1.19V to 30V age. The LT3971 is available in small 10-lead MSOP and n Small Thermally Enhanced 10-Lead MSOP, 16-Lead 3mm × 3mm DFN packages with exposed pads for low MSOP and (3mm × 3mm) DFN Packages thermal resistance. A 16-lead MSOP is also offered which has enhanced pin-to-pin fault tolerance.
APPLICATIONS
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. n Automotive Battery Regulation n Power for Portable Products n Industrial Supplies
TYPICAL APPLICATION No Load Supply Current 3.3V Step Down Converter
3.0 VIN OUTPUT IN REGULATION 4.5V TO 38V VIN OFF ON EN BOOST 2.5 LT3971-5 0.47µF 4.7µH PG SW SS 4.7µF LT3971-3.3 2.0 RT LT3971-3.3 BD VOUT INPUT CURRENT (µA) 1.5 49.9k VOUT 3.3V SYNC GND 1.2A 22µF f = 800kHz 1.0 3971 TA01 5 10 15 20 25 30 35 INPUT VOLTAGE (V) 3971 TA01b 3971fd 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 Revision History Related Parts
