Datasheet LTC1707 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | High Efficiency Monolithic Synchronous Step-Down Switching Regulator |
| Pages / Page | 16 / 1 — FEATURES. DESCRIPTIO. 600mA Output Current (VIN. 4V). High Efficiency: Up … |
| File Format / Size | PDF / 228 Kb |
| Document Language | English |
FEATURES. DESCRIPTIO. 600mA Output Current (VIN. 4V). High Efficiency: Up to 96%. Constant Frequency: 350kHz Synchronizable
Model Line for this Datasheet
Text Version of Document
LTC1707 High Efficiency Monolithic Synchronous Step-Down Switching Regulator
U FEATURES DESCRIPTIO
■
600mA Output Current (VIN
≥
4V)
The LTC®1707 is a high efficiency monolithic current ■
High Efficiency: Up to 96%
mode synchronous buck regulator using a fixed frequency ■
Constant Frequency: 350kHz Synchronizable
architecture. The operating supply range is from 8.5V
to 550kHz
down to 2.85V, making it suitable for both single and dual ■
2.85V to 8.5V VIN Range
lithium-ion battery-powered applications. Burst Mode op- ■ 0.8V Feedback Reference Allows Low Voltage eration provides high efficiency at low load currents. Outputs: 0.8V ≤ VOUT ≤ VIN 100% duty cycle provides low dropout operation, extend- ■
No Schottky Diode Required
ing operating time in battery-powered systems. ■
1.19V
±
1% Reference Output Pin
■ Selectable Burst ModeTM Operation/Pulse The switching frequency is internally set at 350kHz, Skipping Mode allowing the use of small surface mount inductors. For ■ Low Dropout Operation: 100% Duty Cycle noise sensitive applications it can be externally synchro- ■ Precision 2.7V Undervoltage Lockout nized up to 550kHz. Burst Mode operation is inhibited ■ Current Mode Control for Excellent Line and during synchronization or when the SYNC/MODE pin is Load Transient Response pulled low preventing low frequency ripple from interfer- ■ Low Quiescent Current: 200µA ing with audio circuitry. Soft-start is provided by an ■ Shutdown Mode Draws Only 11µA Supply Current external capacitor. ■ Available in 8-Lead SO Package The internal synchronous MOSFET switch increases effi-
U
ciency and eliminates the need for an external Schottky
APPLICATIO S
diode, saving components and board space. Low output ■ Cellular Telephones voltages down to 0.8V are easily achieved due to the 0.8V ■ Portable Instruments internal reference. The LTC1707 comes in an 8-lead SO ■ Wireless Modems package. ■ RF Communications , LTC and LT are registered trademarks of Linear Technology Corporation. ■ Distributed Power Systems Burst Mode is a trademark of Linear Technology Corporation. ■ Single and Dual Cell Lithium
U TYPICAL APPLICATIO
100 VOUT = 3.3V VIN = 3.6V 95 VIN = 6V 90 V 15µH IN* 6 5 V 3V TO V SW OUT IN 85 VIN = 8.4V 8.5V + 3.3V + 100µF 22µF 2 8 249k 6.3V 16V RUN VREF EFFICIENCY (%) 80 LTC1707 7 3 SYNC/MODE VFB 75 1 80.6k ITH GND 47pF 70 4 1 10 100 1000 *VOUT FOLLOWS VIN FOR OUTPUT CURRENT (mA) 3V < VIN < 3.3V 1707 F01a 1707 F01b
Figure 1a. High Efficiency Low Dropout Step-Down Converter Figure 1b. Efficiency vs Output Load Current
1
U FEATURES DESCRIPTIO
■
600mA Output Current (VIN
≥
4V)
The LTC®1707 is a high efficiency monolithic current ■
High Efficiency: Up to 96%
mode synchronous buck regulator using a fixed frequency ■
Constant Frequency: 350kHz Synchronizable
architecture. The operating supply range is from 8.5V
to 550kHz
down to 2.85V, making it suitable for both single and dual ■
2.85V to 8.5V VIN Range
lithium-ion battery-powered applications. Burst Mode op- ■ 0.8V Feedback Reference Allows Low Voltage eration provides high efficiency at low load currents. Outputs: 0.8V ≤ VOUT ≤ VIN 100% duty cycle provides low dropout operation, extend- ■
No Schottky Diode Required
ing operating time in battery-powered systems. ■
1.19V
±
1% Reference Output Pin
■ Selectable Burst ModeTM Operation/Pulse The switching frequency is internally set at 350kHz, Skipping Mode allowing the use of small surface mount inductors. For ■ Low Dropout Operation: 100% Duty Cycle noise sensitive applications it can be externally synchro- ■ Precision 2.7V Undervoltage Lockout nized up to 550kHz. Burst Mode operation is inhibited ■ Current Mode Control for Excellent Line and during synchronization or when the SYNC/MODE pin is Load Transient Response pulled low preventing low frequency ripple from interfer- ■ Low Quiescent Current: 200µA ing with audio circuitry. Soft-start is provided by an ■ Shutdown Mode Draws Only 11µA Supply Current external capacitor. ■ Available in 8-Lead SO Package The internal synchronous MOSFET switch increases effi-
U
ciency and eliminates the need for an external Schottky
APPLICATIO S
diode, saving components and board space. Low output ■ Cellular Telephones voltages down to 0.8V are easily achieved due to the 0.8V ■ Portable Instruments internal reference. The LTC1707 comes in an 8-lead SO ■ Wireless Modems package. ■ RF Communications , LTC and LT are registered trademarks of Linear Technology Corporation. ■ Distributed Power Systems Burst Mode is a trademark of Linear Technology Corporation. ■ Single and Dual Cell Lithium
U TYPICAL APPLICATIO
100 VOUT = 3.3V VIN = 3.6V 95 VIN = 6V 90 V 15µH IN* 6 5 V 3V TO V SW OUT IN 85 VIN = 8.4V 8.5V + 3.3V + 100µF 22µF 2 8 249k 6.3V 16V RUN VREF EFFICIENCY (%) 80 LTC1707 7 3 SYNC/MODE VFB 75 1 80.6k ITH GND 47pF 70 4 1 10 100 1000 *VOUT FOLLOWS VIN FOR OUTPUT CURRENT (mA) 3V < VIN < 3.3V 1707 F01a 1707 F01b
Figure 1a. High Efficiency Low Dropout Step-Down Converter Figure 1b. Efficiency vs Output Load Current
1
