Datasheet LTC1772 (Analog Devices)
| Fabricante | Analog Devices |
| Descripción | Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23 |
| Páginas / Página | 12 / 1 — FEATURES. DESCRIPTIO. High Efficiency: Up to 94%. High Output Currents … |
| Formato / tamaño de archivo | PDF / 172 Kb |
| Idioma del documento | Inglés |
FEATURES. DESCRIPTIO. High Efficiency: Up to 94%. High Output Currents Easily Achieved. Wide V. IN Range: 2.5V to 9.8V
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LTC1772 Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 94%
The LTC®1772 is a constant frequency current mode step- ■
High Output Currents Easily Achieved
down DC/DC controller providing excellent AC and DC load ■
Wide V
and line regulation. The device incorporates an accurate
IN Range: 2.5V to 9.8V
■
Constant Frequency 550kHz Operation
undervoltage lockout feature that shuts down the LTC1772 ■
Burst Mode® Operation at Light Load
when the input voltage falls below 2.0V. ■
Low Dropout: 100% Duty Cycle
The LTC1772 provides a ±2.5% output voltage accuracy ■
Tiny 6-Lead SOT-23 Package
and consumes only 270µA of quiescent current. For ■ 0.8V Reference Allows Low Output Voltages applications where efficiency is a prime consideration, the ■ Current Mode Operation for Excellent Line and Load LTC1772 is configured for Burst Mode operation, which Transient Response enhances efficiency at low output current. ■ Low Quiescent Current: 270µA ■ Shutdown Mode Draws Only 8 To further maximize the life of a battery source, the µA Supply Current ■ external P-channel MOSFET is turned on continuously in ±2.5% Reference Accuracy
U
dropout (100%dutycycle).In shutdown, the device draws
APPLICATIO S
a mere 8µA. High constant operating frequency of 550kHz allows the use of a small external inductor. ■ One or Two Lithium-Ion-Powered Applications ■ The LTC1772 is available in a small footprint 6-lead Cellular Telephones ■ SOT-23. Wireless Modems ■ Portable Computers , LTC and LT are registered trademarks of Linear Technology Corporation. ■ Distributed 3.3V, 2.5V or 1.8V Power Systems Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. ■ Scanners
U TYPICAL APPLICATIO
VIN
Efficiency vs Load Current
2.5V 100 R1 C1 TO 9.8V VIN = 4.2V 0.03Ω 10µF VIN = 3.3V 10V 90 1 6 L1 ITH/RUN PGATE M1 4.7µH VOUT 80 10k LTC1772 2.5V 2 5 + C2A C2B 2A VIN = 6V GND VIN D1 47µF 1µF 70 220pF 3 4 V 6V 10V 174k IN = 8.4V V V FB SENSE– IN = 9.8V EFFICIENCY (%) 60 C1: TAIYO YUDEN LMK325BJ106K-T C2A: SANYO 6TPA47M 80.6k 50 C2B: AVX 0805ZC105KAT1A D1: MOTOROLA MBRM120T3 VOUT = 2.5V L1: MURATA LQN6C-4R7 40 M1: FAIRCHILD FDC638P 1 10 100 1000 10000 1772 F01a R1: IRC LRC-LR1206-01-R030F LOAD CURRENT (mA) 1772 F01b
Figure 1. High Efficiency, High Output Current 2.5V/2A Regulator
1772fb 1
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 94%
The LTC®1772 is a constant frequency current mode step- ■
High Output Currents Easily Achieved
down DC/DC controller providing excellent AC and DC load ■
Wide V
and line regulation. The device incorporates an accurate
IN Range: 2.5V to 9.8V
■
Constant Frequency 550kHz Operation
undervoltage lockout feature that shuts down the LTC1772 ■
Burst Mode® Operation at Light Load
when the input voltage falls below 2.0V. ■
Low Dropout: 100% Duty Cycle
The LTC1772 provides a ±2.5% output voltage accuracy ■
Tiny 6-Lead SOT-23 Package
and consumes only 270µA of quiescent current. For ■ 0.8V Reference Allows Low Output Voltages applications where efficiency is a prime consideration, the ■ Current Mode Operation for Excellent Line and Load LTC1772 is configured for Burst Mode operation, which Transient Response enhances efficiency at low output current. ■ Low Quiescent Current: 270µA ■ Shutdown Mode Draws Only 8 To further maximize the life of a battery source, the µA Supply Current ■ external P-channel MOSFET is turned on continuously in ±2.5% Reference Accuracy
U
dropout (100%dutycycle).In shutdown, the device draws
APPLICATIO S
a mere 8µA. High constant operating frequency of 550kHz allows the use of a small external inductor. ■ One or Two Lithium-Ion-Powered Applications ■ The LTC1772 is available in a small footprint 6-lead Cellular Telephones ■ SOT-23. Wireless Modems ■ Portable Computers , LTC and LT are registered trademarks of Linear Technology Corporation. ■ Distributed 3.3V, 2.5V or 1.8V Power Systems Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. ■ Scanners
U TYPICAL APPLICATIO
VIN
Efficiency vs Load Current
2.5V 100 R1 C1 TO 9.8V VIN = 4.2V 0.03Ω 10µF VIN = 3.3V 10V 90 1 6 L1 ITH/RUN PGATE M1 4.7µH VOUT 80 10k LTC1772 2.5V 2 5 + C2A C2B 2A VIN = 6V GND VIN D1 47µF 1µF 70 220pF 3 4 V 6V 10V 174k IN = 8.4V V V FB SENSE– IN = 9.8V EFFICIENCY (%) 60 C1: TAIYO YUDEN LMK325BJ106K-T C2A: SANYO 6TPA47M 80.6k 50 C2B: AVX 0805ZC105KAT1A D1: MOTOROLA MBRM120T3 VOUT = 2.5V L1: MURATA LQN6C-4R7 40 M1: FAIRCHILD FDC638P 1 10 100 1000 10000 1772 F01a R1: IRC LRC-LR1206-01-R030F LOAD CURRENT (mA) 1772 F01b
Figure 1. High Efficiency, High Output Current 2.5V/2A Regulator
1772fb 1