Datasheet LTC3701 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 2-Phase, Low Input Voltage, Dual Step-Down DC/DC Controller |
| Pages / Page | 20 / 1 — FEATURES. DESCRIPTIO. Out-of-Phase Controllers Reduce Required. Input … |
| File Format / Size | PDF / 261 Kb |
| Document Language | English |
FEATURES. DESCRIPTIO. Out-of-Phase Controllers Reduce Required. Input Capacitance. True PLL for Frequency Locking or Frequency
Model Line for this Datasheet
Text Version of Document
LTC3701 2-Phase, Low Input Voltage, Dual Step-Down DC/DC Controller
U FEATURES DESCRIPTIO
■
Out-of-Phase Controllers Reduce Required
The LTC®3701 is a 2-phase dual constant frequency cur-
Input Capacitance
rent mode step-down DC/DC controller providing excellent ■
True PLL for Frequency Locking or Frequency
load and line regulation. Power loss and noise due to ESR
Adjustment
of the input capacitor are minimized by operating the two ■
Operating Frequency Range: 300kHz to 750kHz
controller output stages out-of-phase. ■ Wide VIN Range: 2.5V to 10V The LTC3701 provides a 0.8V ±2% voltage reference and ■ Constant Frequency Current Mode Architecture consumes only 460µA of quiescent current. To further ■ Low Dropout: 100% Duty Cycle maximize the life of a battery source, the external ■ Power Good Output Voltage Monitor P-channel MOSFET is turned on continuously in dropout ■ Internal Soft-Start Circuitry (100% duty cycle). ■ Selectable Burst Mode®/Pulse Skipping Operation at Light Loads Switching frequency is internally set at 550kHz, allowing ■ Output Overvoltage Protection the use of small inductors and capacitors. For noise sen- ■ Low Quiescent sitive applications, the LTC3701 can be externally syn- Current: 460µA ■ 0.8V chronized using its phase-locked loop. The frequency can ±2% Voltage Reference ■ Small 16-Lead Narrow SSOP Package also be externally set from 300kHz to 750kHz by applying a voltage to the PLLLPF pin. Burst Mode operation is inhib-
U
ited during synchronization or when the EXTCLK/MODE
APPLICATIO S
pin is pulled low to reduce noise and RF interference. ■ One or Two Lithium-Ion Powered Applications The LTC3701 contains independent internal soft-start ■ Notebook and Handheld Computers circuitry for each controller. Other features include a ■ Personal Digital Assistants power good output voltage monitor and output overvolt- ■ Portable Instruments age and short-circuit protection. ■ Distributed DC Power Systems The LTC3701 is available in a small footprint 16-lead nar- , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. row SSOP package.
U TYPICAL APPLICATIO
VIN 2.5V TO 9.8V
Efficiency vs Load Current
100 169k 1 16 V V IN = 3.3V SENSE1– SENSE1+ IN = 4.2V L1 VOUT1 3 15 0.03Ω 90 78.7k 220pF V 2.5V FB1 VIN 4.7µH 10k M1 + 2 14 2A ITH/RUN1 PGATE1 D1 47µF 10µF 80 4 LTC3701 13 SGND PGND VIN = 6V 6 12 I VIN = 8.4V TH/RUN2 PGATE2 70 10k 5 11 D2 80.6k 220pF V 47µF FB2 PGOOD + 7 10 M2 L2 EFFICIENCY (%) 60 PLLLPF EXTCLK/MODE VOUT2 0.03Ω 4.7µH 8 9 1.8V 100k SENSE2– SENSE2+ 2A 50 VOUT = 2.5V 40 3701 F01a D1, D2: IR10BQ015 L1, L2: LQN6C-4R7 M1, M2: FDC638P 1 10 100 1000 10000 LOAD CURRENT (mA)
Figure 1. High Efficiency 2-Phase 550kHz Dual Step-Down Converter
3701 F01b 3701fa 1
U FEATURES DESCRIPTIO
■
Out-of-Phase Controllers Reduce Required
The LTC®3701 is a 2-phase dual constant frequency cur-
Input Capacitance
rent mode step-down DC/DC controller providing excellent ■
True PLL for Frequency Locking or Frequency
load and line regulation. Power loss and noise due to ESR
Adjustment
of the input capacitor are minimized by operating the two ■
Operating Frequency Range: 300kHz to 750kHz
controller output stages out-of-phase. ■ Wide VIN Range: 2.5V to 10V The LTC3701 provides a 0.8V ±2% voltage reference and ■ Constant Frequency Current Mode Architecture consumes only 460µA of quiescent current. To further ■ Low Dropout: 100% Duty Cycle maximize the life of a battery source, the external ■ Power Good Output Voltage Monitor P-channel MOSFET is turned on continuously in dropout ■ Internal Soft-Start Circuitry (100% duty cycle). ■ Selectable Burst Mode®/Pulse Skipping Operation at Light Loads Switching frequency is internally set at 550kHz, allowing ■ Output Overvoltage Protection the use of small inductors and capacitors. For noise sen- ■ Low Quiescent sitive applications, the LTC3701 can be externally syn- Current: 460µA ■ 0.8V chronized using its phase-locked loop. The frequency can ±2% Voltage Reference ■ Small 16-Lead Narrow SSOP Package also be externally set from 300kHz to 750kHz by applying a voltage to the PLLLPF pin. Burst Mode operation is inhib-
U
ited during synchronization or when the EXTCLK/MODE
APPLICATIO S
pin is pulled low to reduce noise and RF interference. ■ One or Two Lithium-Ion Powered Applications The LTC3701 contains independent internal soft-start ■ Notebook and Handheld Computers circuitry for each controller. Other features include a ■ Personal Digital Assistants power good output voltage monitor and output overvolt- ■ Portable Instruments age and short-circuit protection. ■ Distributed DC Power Systems The LTC3701 is available in a small footprint 16-lead nar- , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. row SSOP package.
U TYPICAL APPLICATIO
VIN 2.5V TO 9.8V
Efficiency vs Load Current
100 169k 1 16 V V IN = 3.3V SENSE1– SENSE1+ IN = 4.2V L1 VOUT1 3 15 0.03Ω 90 78.7k 220pF V 2.5V FB1 VIN 4.7µH 10k M1 + 2 14 2A ITH/RUN1 PGATE1 D1 47µF 10µF 80 4 LTC3701 13 SGND PGND VIN = 6V 6 12 I VIN = 8.4V TH/RUN2 PGATE2 70 10k 5 11 D2 80.6k 220pF V 47µF FB2 PGOOD + 7 10 M2 L2 EFFICIENCY (%) 60 PLLLPF EXTCLK/MODE VOUT2 0.03Ω 4.7µH 8 9 1.8V 100k SENSE2– SENSE2+ 2A 50 VOUT = 2.5V 40 3701 F01a D1, D2: IR10BQ015 L1, L2: LQN6C-4R7 M1, M2: FDC638P 1 10 100 1000 10000 LOAD CURRENT (mA)
Figure 1. High Efficiency 2-Phase 550kHz Dual Step-Down Converter
3701 F01b 3701fa 1
