Datasheet LT3991, LT3991-3.3, LT3991-5 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 55V, 1.2A Step-Down Regulator with 2.8μA Quiescent Current |
| Pages / Page | 24 / 1 — FeaTures. DescripTion. Ultralow Quiescent Current:. 2.8µA IQ Regulating … |
| File Format / Size | PDF / 398 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
Text Version of Document
LT3991/LT3991-3.3/LT3991-5 55V, 1.2A Step-Down Regulator with 2.8µA Quiescent Current
FeaTures DescripTion
n
Ultralow Quiescent Current:
The LT®3991 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 55V. Low quiescent current design consumes only
2.1µA IQ Regulating 12VIN
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 55V
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 0.44Ω 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 LT3991, reducing the input supply current to n Power Good Flag 700nA. A capacitor on the SS pin provides a controlled n Soft-Start CapabilityV inrush current (soft-start). A power good flag signals n Internal Compensation when VOUT reaches 91% of the programmed output volt- n Saturating Switch Design: 0.44Ω On-Resistance age. The LT3991 is available in small 10-pin MSOP and n Output Voltage: 1.19V to 30V 3mm × 3mm DFN packages with exposed pads for low n Small Thermally Enhanced 10-Pin MSOP Package thermal resistance. and (3mm L × 3mm) DFN Packages , LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
applicaTions
n Automotive Battery Regulation n Power for Portable Products n Industrial Supplies
Typical applicaTion No Load Supply Current
3.0
3.3V Step Down Converter
OUTPUT IN REGULATION VIN 4.3V TO 55V 2.5 VIN OFF ON EN./UVLO BOOST 0.47µF LT3991-5 12µH PG 2.0 SW SS LT3991-3.3 4.7µF LT3991-3.3 RT INPUT CURRENT (µA) 1.5 BD VOUT 118k VOUT 3.3V SYNC GND 1.2A 47µF 1.0 5 10 15 20 25 30 35 40 45 50 55 f = 400kHz 3991 TA01a INPUT VOLTAGE (V) 3991 G06 3991fa 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®3991 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 55V. Low quiescent current design consumes only
2.1µA IQ Regulating 12VIN
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 55V
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 0.44Ω 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 LT3991, reducing the input supply current to n Power Good Flag 700nA. A capacitor on the SS pin provides a controlled n Soft-Start CapabilityV inrush current (soft-start). A power good flag signals n Internal Compensation when VOUT reaches 91% of the programmed output volt- n Saturating Switch Design: 0.44Ω On-Resistance age. The LT3991 is available in small 10-pin MSOP and n Output Voltage: 1.19V to 30V 3mm × 3mm DFN packages with exposed pads for low n Small Thermally Enhanced 10-Pin MSOP Package thermal resistance. and (3mm L × 3mm) DFN Packages , LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
applicaTions
n Automotive Battery Regulation n Power for Portable Products n Industrial Supplies
Typical applicaTion No Load Supply Current
3.0
3.3V Step Down Converter
OUTPUT IN REGULATION VIN 4.3V TO 55V 2.5 VIN OFF ON EN./UVLO BOOST 0.47µF LT3991-5 12µH PG 2.0 SW SS LT3991-3.3 4.7µF LT3991-3.3 RT INPUT CURRENT (µA) 1.5 BD VOUT 118k VOUT 3.3V SYNC GND 1.2A 47µF 1.0 5 10 15 20 25 30 35 40 45 50 55 f = 400kHz 3991 TA01a INPUT VOLTAGE (V) 3991 G06 3991fa 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
