Datasheet LTC1779 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 250mA Current Mode Step-Down DC/DC Converter in SOT-23 |
| Pages / Page | 14 / 1 — FeaTures. DescripTion. High Efficiency: Up to 94%. 250mA Output Current. … |
| File Format / Size | PDF / 267 Kb |
| Document Language | English |
FeaTures. DescripTion. High Efficiency: Up to 94%. 250mA Output Current. Wide VIN Range: 2.5V to 9.8V
Model Line for this Datasheet
Text Version of Document
LTC1779 250mA Current Mode Step-Down DC/DC Converter in ThinSOT
FeaTures DescripTion
n
High Efficiency: Up to 94%
The LTC®1779 is a constant frequency current mode step- n
250mA Output Current
down DC/DC converter in a 6-lead ThinSOT package. The n
Wide VIN Range: 2.5V to 9.8V
part operates with a 2.5V to 9.8V input and can provide n
550kHz Constant Frequency Operation
up to 250mA of output current. Current mode control n
Burst Mode™ Operation at Light Load
provides excellent AC and DC load and line regulation. n
Low Dropout: 100% Duty Cycle
The device incorporates an accurate undervoltage lockout n 0.8V Reference Allows Low Output Voltages feature that shuts down the LTC1779 when the input volt- n ±2.5% Reference Accuracy age falls below 2V. n Current Mode Operation for Excellent Line and Load The LTC1779 boasts a ±2.5% output voltage accuracy Transient Response and consumes only 135µA of quiescent current. For ap- n Low Quiescent Current: 135µA plications where efficiency is a prime consideration, the n Shutdown Mode Draws Only 8µA Supply Current LTC1779 is configured for Burst Mode operation, which n Low Profile (1mm) ThinSOT™ Package enhances efficiency at low output current. To further maximize the life of a battery source, the
applicaTions
internal P-channel MOSFET is turned on continuously in n dropout (100% duty cycle). In shutdown, the device draws 1- or 2-Cell Lithium-Ion-Powered Applications n a mere 8µA. High constant operating frequency of 550kHz Cellular Telephones n allows the use of a small external inductor. Wireless Modems n Portable Computers The LTC1779 is available in a low profile (1mm) ThinSOT n Distributed 3.3V, 2.5V or 1.8V Power Systems package. n Scanners L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Typical applicaTion
VIN 2.5V
Efficiency vs Load Current
C1 C3 TO 9.8V 10µF 100 0.1µF L1 16V 22µH 90 1 6 VOUT ITH/RUN SW 2.5V + V C2 IN = 3.3V 100mA 20k LTC1779 169k 80 D1 47µF 2 5 VIN = 6V GND V 6V IN 70 100pF R1 78.7k V 3 4 10Ω IN = 9.8V V 60 FB SENSE– EFFICIENCY (%) 1779 F01a 50 C1: TAIYO YUDEN CERAMIC EMK325BJ106MNT C2: SANYO POSCAP 6TPA47M D1: IR10BQ015 40 VOUT = 2.5V L1: COILTRONICS UP1B220 RSENSE = 10Ω 300.1 1 10 100 1000
Figure 1. LTC1779 High Efficiency 2.5V/100mA Step-Down Converter
LOAD CURRENT (mA) 1779 F01b 1779fa For more information www.linear.com/LTC1779 1
FeaTures DescripTion
n
High Efficiency: Up to 94%
The LTC®1779 is a constant frequency current mode step- n
250mA Output Current
down DC/DC converter in a 6-lead ThinSOT package. The n
Wide VIN Range: 2.5V to 9.8V
part operates with a 2.5V to 9.8V input and can provide n
550kHz Constant Frequency Operation
up to 250mA of output current. Current mode control n
Burst Mode™ Operation at Light Load
provides excellent AC and DC load and line regulation. n
Low Dropout: 100% Duty Cycle
The device incorporates an accurate undervoltage lockout n 0.8V Reference Allows Low Output Voltages feature that shuts down the LTC1779 when the input volt- n ±2.5% Reference Accuracy age falls below 2V. n Current Mode Operation for Excellent Line and Load The LTC1779 boasts a ±2.5% output voltage accuracy Transient Response and consumes only 135µA of quiescent current. For ap- n Low Quiescent Current: 135µA plications where efficiency is a prime consideration, the n Shutdown Mode Draws Only 8µA Supply Current LTC1779 is configured for Burst Mode operation, which n Low Profile (1mm) ThinSOT™ Package enhances efficiency at low output current. To further maximize the life of a battery source, the
applicaTions
internal P-channel MOSFET is turned on continuously in n dropout (100% duty cycle). In shutdown, the device draws 1- or 2-Cell Lithium-Ion-Powered Applications n a mere 8µA. High constant operating frequency of 550kHz Cellular Telephones n allows the use of a small external inductor. Wireless Modems n Portable Computers The LTC1779 is available in a low profile (1mm) ThinSOT n Distributed 3.3V, 2.5V or 1.8V Power Systems package. n Scanners L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Typical applicaTion
VIN 2.5V
Efficiency vs Load Current
C1 C3 TO 9.8V 10µF 100 0.1µF L1 16V 22µH 90 1 6 VOUT ITH/RUN SW 2.5V + V C2 IN = 3.3V 100mA 20k LTC1779 169k 80 D1 47µF 2 5 VIN = 6V GND V 6V IN 70 100pF R1 78.7k V 3 4 10Ω IN = 9.8V V 60 FB SENSE– EFFICIENCY (%) 1779 F01a 50 C1: TAIYO YUDEN CERAMIC EMK325BJ106MNT C2: SANYO POSCAP 6TPA47M D1: IR10BQ015 40 VOUT = 2.5V L1: COILTRONICS UP1B220 RSENSE = 10Ω 300.1 1 10 100 1000
Figure 1. LTC1779 High Efficiency 2.5V/100mA Step-Down Converter
LOAD CURRENT (mA) 1779 F01b 1779fa For more information www.linear.com/LTC1779 1
