Datasheet LTC3801, LTC3801B (Analog Devices)
| 制造商 | Analog Devices |
| 描述 | Micropower Constant Frequency Step-Down DC/DC Controllers in ThinSOT |
| 页数 / 页 | 12 / 1 — FEATURES. DESCRIPTIO. High Efficiency: Up to 94%. Very Low No-Load … |
| 文件格式/大小 | PDF / 243 Kb |
| 文件语言 | 英语 |
FEATURES. DESCRIPTIO. High Efficiency: Up to 94%. Very Low No-Load Quiescent Current:. Only 16. A (LTC3801)
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LTC3801/LTC3801B Micropower Constant Frequency Step-Down DC/DC Controllers in ThinSOT
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 94%
The LTC®3801/LTC3801B are constant frequency cur- ■
Very Low No-Load Quiescent Current:
rent mode step-down DC/DC controllers in a low profile
Only 16
µ
A (LTC3801)
(1mm max) 6-lead SOT-23 (ThinSOTTM) package. The ■
High Output Currents Easily Achieved
parts provide excellent AC and DC load and line regula- ■
Internal Soft-Start
tion with ±1.5% output voltage accuracy. The LTC3801 ■
Wide VIN Range: 2.4V to 9.8V
consumes only 195µA of quiescent current in normal ■
Low Dropout: 100% Duty Cycle
operation, dropping to 16µA under no-load conditions. ■
Constant Frequency 550kHz Operation
The LTC3801/LTC3801B incorporate an undervoltage lock- ■ Burst Mode® Operation for High Efficiency out feature that shuts down the device when the input at Light Loads (LTC3801) voltage falls below 2.2V. The LTC3801 automatically ■ Burst Mode Operation Disabled for Lower Output switches into Burst Mode operation at light loads which Ripple at Light Loads (LTC3801B) enhances efficiency at low output current. In the LTC3801B, ■ Output Voltage as Low as 0.8V Burst Mode operation is disabled for lower output ripple at ■ ±1.5% Voltage Reference Accuracy light loads. ■ Current Mode Operation for Excellent Line and Load Transient Response To further maximize the life of a battery source, the ■ Only 6µA Supply Current in Shutdown (LTC3801) external P-channel MOSFET is turned on continuously in ■ Low Profile (1mm) SOT-23 Package dropout (100% duty cycle). High switching frequency of 550kHz allows the use of a small inductor.
U APPLICATIO S
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. ■ 1- or 2-Cell Li-Ion Battery-Powered Applications ThinSOT is a trademark of Linear Technology Corporation. ■ Wireless Devices ■ Portable Computers ■ Distributed Power Systems
U TYPICAL APPLICATIO LTC3801 Efficiency vs Load Current*
100 VOUT = 2.5V 95 VIN = 3.3V
550kHz Micropower Step-Down DC/DC Controller
VIN = 4.2V 90 220pF 85 VIN = 6.6V 10k VIN 80 I 2.7V TO 9.8V TH/RUN VIN LTC3801/ 10µF 75 0.025Ω LTC3801B V V IN = 9.8V IN = 8.4V 70 GND SENSE– EFFICIENCY (%) V 65 FB PGATE 402k 60 866k 4.7µH V 55 OUT 2.5V + 50 2A 0.1 1 10 100 1000 10000 47µF LOAD CURRENT (mA) 3801 TA02 3801 TA01 *SEE NO-LOAD IQ vs INPUT VOLTAGE ON THE LAST PAGE OF THIS DATA SHEET sn3801 3801fs 1
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 94%
The LTC®3801/LTC3801B are constant frequency cur- ■
Very Low No-Load Quiescent Current:
rent mode step-down DC/DC controllers in a low profile
Only 16
µ
A (LTC3801)
(1mm max) 6-lead SOT-23 (ThinSOTTM) package. The ■
High Output Currents Easily Achieved
parts provide excellent AC and DC load and line regula- ■
Internal Soft-Start
tion with ±1.5% output voltage accuracy. The LTC3801 ■
Wide VIN Range: 2.4V to 9.8V
consumes only 195µA of quiescent current in normal ■
Low Dropout: 100% Duty Cycle
operation, dropping to 16µA under no-load conditions. ■
Constant Frequency 550kHz Operation
The LTC3801/LTC3801B incorporate an undervoltage lock- ■ Burst Mode® Operation for High Efficiency out feature that shuts down the device when the input at Light Loads (LTC3801) voltage falls below 2.2V. The LTC3801 automatically ■ Burst Mode Operation Disabled for Lower Output switches into Burst Mode operation at light loads which Ripple at Light Loads (LTC3801B) enhances efficiency at low output current. In the LTC3801B, ■ Output Voltage as Low as 0.8V Burst Mode operation is disabled for lower output ripple at ■ ±1.5% Voltage Reference Accuracy light loads. ■ Current Mode Operation for Excellent Line and Load Transient Response To further maximize the life of a battery source, the ■ Only 6µA Supply Current in Shutdown (LTC3801) external P-channel MOSFET is turned on continuously in ■ Low Profile (1mm) SOT-23 Package dropout (100% duty cycle). High switching frequency of 550kHz allows the use of a small inductor.
U APPLICATIO S
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. ■ 1- or 2-Cell Li-Ion Battery-Powered Applications ThinSOT is a trademark of Linear Technology Corporation. ■ Wireless Devices ■ Portable Computers ■ Distributed Power Systems
U TYPICAL APPLICATIO LTC3801 Efficiency vs Load Current*
100 VOUT = 2.5V 95 VIN = 3.3V
550kHz Micropower Step-Down DC/DC Controller
VIN = 4.2V 90 220pF 85 VIN = 6.6V 10k VIN 80 I 2.7V TO 9.8V TH/RUN VIN LTC3801/ 10µF 75 0.025Ω LTC3801B V V IN = 9.8V IN = 8.4V 70 GND SENSE– EFFICIENCY (%) V 65 FB PGATE 402k 60 866k 4.7µH V 55 OUT 2.5V + 50 2A 0.1 1 10 100 1000 10000 47µF LOAD CURRENT (mA) 3801 TA02 3801 TA01 *SEE NO-LOAD IQ vs INPUT VOLTAGE ON THE LAST PAGE OF THIS DATA SHEET sn3801 3801fs 1