Datasheet LTC1878 (Analog Devices)
| 制造商 | Analog Devices |
| 描述 | High Efficiency Monolithic Synchronous Step-Down Regulator |
| 页数 / 页 | 16 / 1 — FEATURES. DESCRIPTIO. High Efficiency: Up to 95%. Very Low Quiescent … |
| 文件格式/大小 | PDF / 239 Kb |
| 文件语言 | 英语 |
FEATURES. DESCRIPTIO. High Efficiency: Up to 95%. Very Low Quiescent Current: Only 10. During Operation
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LTC1878 High Efficiency Monolithic Synchronous Step-Down Regulator
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 95%
The LTC®1878 is a high efficiency monolithic synchro- ■
Very Low Quiescent Current: Only 10
µ
A
nous buck regulator using a constant frequency, current
During Operation
mode architecture. Supply current during operation is ■
600mA Output Current at VIN = 3.3V
only 10µA and drops to < 1µA in shutdown. The 2.65V to ■
2.65V to 6V Input Voltage Range
6V input voltage range makes the LTC1878 ideally suited ■
550kHz Constant Frequency Operation
for single Li-Ion battery-powered applications. 100% duty ■ Synchronizable from 400kHz to 700kHz cycle provides low dropout operation, extending battery ■ Selectable Burst ModeTM Operation or life in portable systems. Pulse Skipping Mode Switching frequency is internally set at 550kHz, allowing ■
No Schottky Diode Required
the use of small surface mount inductors and capacitors. ■
Low Dropout Operation: 100% Duty Cycle
For noise sensitive applications the LTC1878 can be ■ 0.8V Reference Allows Low Output Voltages externally synchronized from 400kHz to 700kHz. Burst ■ Shutdown Mode Draws < 1µA Supply Current Mode operation is inhibited during synchronization or ■ ±2% Output Voltage Accuracy when the SYNC/MODE pin is pulled low, preventing low ■ Current Mode Control for Excellent Line and Load Transient Response frequency ripple from interfering with audio circuitry. ■ Overcurrent and Overtemperature Protected The internal synchronous switch increases efficiency and ■ Available in 8-Lead MSOP 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 LTC1878 is available in a ■ Cellular Telephones space saving 8-lead MSOP package. ■ Wireless Modems For higher input voltage (11V abs max) applications, refer ■ Personal Information Appliances to the LTC1877 data sheet. ■ Portable Instruments , LTC and LT are registered trademarks of Linear Technology Corporation. ■ Distributed Power Systems Burst Mode is a trademark of Linear Technology Corporation. ■ Battery-Powered Equipment
U Efficiency vs Output Load Current TYPICAL APPLICATIO
100
High Efficiency Step-Down Converter
95 VIN = 3.6V 10 V µH* IN 7 5 90 V † 2.65V SYNC SW OUT V 3.3V IN = 4.2V TO 6V 22µF** 6 20pF V 85 CER IN + 1 LTC1878 47µF*** RUN VIN = 6V 2 3 887k EFFICIENCY (%) 80 I V TH FB GND 220pF 4 280k 75 Burst Mode OPERATION VOUT = 3.3V 1878 TA01 L = 10µH *TOKO D62CB A920CY-100M 70 **TAIYO-YUDEN CERAMIC JMK325BJ226MM 0.1 1 10 100 1000 ***SANYO POSCAP 6TPA47M OUTPUT CURRENT (mA) †VOUT CONNECTED TO VIN FOR 2.65V < VIN < 3.3V 1878 TA02 1
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 95%
The LTC®1878 is a high efficiency monolithic synchro- ■
Very Low Quiescent Current: Only 10
µ
A
nous buck regulator using a constant frequency, current
During Operation
mode architecture. Supply current during operation is ■
600mA Output Current at VIN = 3.3V
only 10µA and drops to < 1µA in shutdown. The 2.65V to ■
2.65V to 6V Input Voltage Range
6V input voltage range makes the LTC1878 ideally suited ■
550kHz Constant Frequency Operation
for single Li-Ion battery-powered applications. 100% duty ■ Synchronizable from 400kHz to 700kHz cycle provides low dropout operation, extending battery ■ Selectable Burst ModeTM Operation or life in portable systems. Pulse Skipping Mode Switching frequency is internally set at 550kHz, allowing ■
No Schottky Diode Required
the use of small surface mount inductors and capacitors. ■
Low Dropout Operation: 100% Duty Cycle
For noise sensitive applications the LTC1878 can be ■ 0.8V Reference Allows Low Output Voltages externally synchronized from 400kHz to 700kHz. Burst ■ Shutdown Mode Draws < 1µA Supply Current Mode operation is inhibited during synchronization or ■ ±2% Output Voltage Accuracy when the SYNC/MODE pin is pulled low, preventing low ■ Current Mode Control for Excellent Line and Load Transient Response frequency ripple from interfering with audio circuitry. ■ Overcurrent and Overtemperature Protected The internal synchronous switch increases efficiency and ■ Available in 8-Lead MSOP 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 LTC1878 is available in a ■ Cellular Telephones space saving 8-lead MSOP package. ■ Wireless Modems For higher input voltage (11V abs max) applications, refer ■ Personal Information Appliances to the LTC1877 data sheet. ■ Portable Instruments , LTC and LT are registered trademarks of Linear Technology Corporation. ■ Distributed Power Systems Burst Mode is a trademark of Linear Technology Corporation. ■ Battery-Powered Equipment
U Efficiency vs Output Load Current TYPICAL APPLICATIO
100
High Efficiency Step-Down Converter
95 VIN = 3.6V 10 V µH* IN 7 5 90 V † 2.65V SYNC SW OUT V 3.3V IN = 4.2V TO 6V 22µF** 6 20pF V 85 CER IN + 1 LTC1878 47µF*** RUN VIN = 6V 2 3 887k EFFICIENCY (%) 80 I V TH FB GND 220pF 4 280k 75 Burst Mode OPERATION VOUT = 3.3V 1878 TA01 L = 10µH *TOKO D62CB A920CY-100M 70 **TAIYO-YUDEN CERAMIC JMK325BJ226MM 0.1 1 10 100 1000 ***SANYO POSCAP 6TPA47M OUTPUT CURRENT (mA) †VOUT CONNECTED TO VIN FOR 2.65V < VIN < 3.3V 1878 TA02 1