Datasheet LTC3405A (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 1.5MHz, 300mA Synchronous Step-Down Regulator in ThinSOT |
| Pages / Page | 16 / 1 — FEATURES. DESCRIPTIO. High Efficiency: Up to 96%. Very Low Quiescent … |
| File Format / Size | PDF / 219 Kb |
| Document Language | English |
FEATURES. DESCRIPTIO. High Efficiency: Up to 96%. Very Low Quiescent Current: Only 20. During Operation
Model Line for this Datasheet
Text Version of Document
LTC3405A 1.5MHz, 300mA Synchronous Step-Down Regulator in ThinSOT
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 96%
The LTC®3405A is a high efficiency monolithic synchro- ■
Very Low Quiescent Current: Only 20
µ
A
nous buck regulator using a constant frequency, current
During Operation
mode architecture. Supply current during operation is ■
300mA Output Current at VIN = 3V
only 20µA and drops to <1µA in shutdown. The 2.5V to ■
2.5V to 5.5V Input Voltage Range
5.5V input voltage range makes the LTC3405A ideally ■
1.5MHz Constant Frequency Operation
suited for single Li-Ion battery-powered applications. 100% ■
No Schottky Diode Required
duty cycle provides low dropout operation, extending ■
Low Dropout Operation: 100% Duty Cycle
battery life in portable systems. ■
Stable with Ceramic Capacitors
Switching frequency is internally set at 1.5MHz, allowing ■ 0.8V Reference Allows Low Output Voltages the use of small surface mount inductors and capacitors. ■ Shutdown Mode Draws < 1µA Supply Current The LTC3405A is specifically designed to work well with ■ ±2% Output Voltage Accuracy ■ Current Mode Operation for Excellent Line and ceramic output capacitors, achieving very low output Load Transient Response voltage ripple and a small PCB footprint. ■ Overtemperature Protected The internal synchronous switch increases efficiency and ■ Low Profile (1mm) ThinSOTTM Package eliminates the need for an external Schottky diode. Low
U
output voltages are easily supported with the 0.8V feed-
APPLICATIO S
back reference voltage. The LTC3405A is available in a low profile (1mm) ThinSOT package. ■ Cellular Telephones ■ Personal Information Appliances For fixed 1.5V and 1.8V output versions, refer to the ■ Wireless and DSL Modems LTC3405A-1.5/LTC3405A-1.8 data sheet. ■ Digital Still Cameras , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. ■ MP3 Players Protected by U.S. Patents, including 6580258, 5481178. ■ Portable Instruments
U TYPICAL APPLICATIO
100 95 VIN = 3.6V V 4.7µH** IN 4 3 90 V 2.7V V OUT* IN SW 3.3V TO 5.5V C 22pF IN† C 85 2.2µF LTC3405A OUT†† 1 4.7µF V CER IN = 4.2V RUN CER 80 6 5 MODE VFB 75 887k EFFICIENCY (%) GND VIN = 5.5V 280k 70 2 3405A F01a 65 *VOUT CONNECTED TO VIN FOR 2.7V < VIN < 3.3V **MURATA LQH3C4R7M34 60 †TAIYO YUDEN LMK212BJ225MG 0.1 1 10 100 1000 ††TAIYO YUDEN JMK212BJ475MG OUTPUT CURRENT (mA) 3405A F01b
Figure 1a. High Efficiency Step-Down Converter Figure 1b. Efficiency vs Load Current
3405afa 1
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 96%
The LTC®3405A is a high efficiency monolithic synchro- ■
Very Low Quiescent Current: Only 20
µ
A
nous buck regulator using a constant frequency, current
During Operation
mode architecture. Supply current during operation is ■
300mA Output Current at VIN = 3V
only 20µA and drops to <1µA in shutdown. The 2.5V to ■
2.5V to 5.5V Input Voltage Range
5.5V input voltage range makes the LTC3405A ideally ■
1.5MHz Constant Frequency Operation
suited for single Li-Ion battery-powered applications. 100% ■
No Schottky Diode Required
duty cycle provides low dropout operation, extending ■
Low Dropout Operation: 100% Duty Cycle
battery life in portable systems. ■
Stable with Ceramic Capacitors
Switching frequency is internally set at 1.5MHz, allowing ■ 0.8V Reference Allows Low Output Voltages the use of small surface mount inductors and capacitors. ■ Shutdown Mode Draws < 1µA Supply Current The LTC3405A is specifically designed to work well with ■ ±2% Output Voltage Accuracy ■ Current Mode Operation for Excellent Line and ceramic output capacitors, achieving very low output Load Transient Response voltage ripple and a small PCB footprint. ■ Overtemperature Protected The internal synchronous switch increases efficiency and ■ Low Profile (1mm) ThinSOTTM Package eliminates the need for an external Schottky diode. Low
U
output voltages are easily supported with the 0.8V feed-
APPLICATIO S
back reference voltage. The LTC3405A is available in a low profile (1mm) ThinSOT package. ■ Cellular Telephones ■ Personal Information Appliances For fixed 1.5V and 1.8V output versions, refer to the ■ Wireless and DSL Modems LTC3405A-1.5/LTC3405A-1.8 data sheet. ■ Digital Still Cameras , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. ■ MP3 Players Protected by U.S. Patents, including 6580258, 5481178. ■ Portable Instruments
U TYPICAL APPLICATIO
100 95 VIN = 3.6V V 4.7µH** IN 4 3 90 V 2.7V V OUT* IN SW 3.3V TO 5.5V C 22pF IN† C 85 2.2µF LTC3405A OUT†† 1 4.7µF V CER IN = 4.2V RUN CER 80 6 5 MODE VFB 75 887k EFFICIENCY (%) GND VIN = 5.5V 280k 70 2 3405A F01a 65 *VOUT CONNECTED TO VIN FOR 2.7V < VIN < 3.3V **MURATA LQH3C4R7M34 60 †TAIYO YUDEN LMK212BJ225MG 0.1 1 10 100 1000 ††TAIYO YUDEN JMK212BJ475MG OUTPUT CURRENT (mA) 3405A F01b
Figure 1a. High Efficiency Step-Down Converter Figure 1b. Efficiency vs Load Current
3405afa 1
