Datasheet LT3504 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Quad 40V/1A Step-Down Switching Regulator with 100% Duty Cycle Operation |
| Pages / Page | 24 / 1 — FeaTures. DescripTion. Wide Input Range: 3.2V to 40V. Four 1A Outputs. … |
| File Format / Size | PDF / 498 Kb |
| Document Language | English |
FeaTures. DescripTion. Wide Input Range: 3.2V to 40V. Four 1A Outputs. 100% Duty Cycle Operation
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Text Version of Document
LT3504 Quad 40V/1A Step-Down Switching Regulator with 100% Duty Cycle Operation
FeaTures DescripTion
n
Wide Input Range: 3.2V to 40V
The LT®3504 consists of four 1A output current buck n
Four 1A Outputs
regulators. The LT3504 has a wide operating input range n
100% Duty Cycle Operation
of 3.2V to 40V. An on-chip boost regulator allows each n
Resistor-Programmed Constant Frequency
channel to operate up to 100% duty cycle and eliminates n
Short-Circuit Robust the need for four external charge pump circuits. The LT3504 n Wide SYNC Range: 350kHz to 2.2MHz is designed to minimize external component count and n Anti-Phase Switching Reduces Ripple results in a simple and small application circuit. n 800mV FB Voltage The LT3504 operates robustly in fault conditions. Cycle- n Independent Run/Soft-Start Pins by-cycle peak current limit and catch diode current limit n Shutdown with UVLO sensing protect the part during overload conditions. Ther- n Internal Compensation mal shutdown protects the power switches at elevated n Thermal Shutdown temperatures. Soft-start helps keep the peak inductor n Tiny 28-Lead (4mm × 5mm) Thermally Enhanced current under control during startup. QFN Package The LT3504 also features output voltage tracking and
applicaTions
sequencing, programmable frequency, programmable undervoltage lockout, and a power good pin to indicate n Automotive Battery Regulation when all outputs are in regulation. n Industrial Control Supplies L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks n Wall Transformer Regulation of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Distributed Supply Regulation
Typical applicaTion Quad Buck Regulator in 4 × 5 QFN LT3504 Start-Up and Shutdown Waveform. VIN (Top Trace) Is Ramped
10µH SW4 5V/1A
from 0V Up to 8V and Then Back Down
52.3k 10µF
to 0V. The Other Four Traces Are the
DA4 SKY FB4
Output Voltages of All Four Channels
LT3504 10k 1µF 10µH 6.8µH VIN 5.4V to 20V SW5 V SW3 3.3V/1A IN 1V/DIV TRANSIENT TO 40V 5V CHANNEL BEGINS 10µF 100% DC OPERATION EN/UVLO DA3 31.6k VIN FB3 3.3V CHANNEL BEGINS CH4 1V/DIV VIN 10k 100% DC OPERATION VIN VIN 4.7µH CH3 1V/DIV RUN/SS1 SW2 UVLO = ~2.9V 2.5V/1A PARTS SHUTS RUN/SS2 CH2 1V/DIV 1µF 22.1k OFF RUN/SS3 DA2 22µF CH1 1V/DIV RUN/SS4 FB2 50nF 10k RT/SYNC 3.3µH 3504 TA01b 100ms/DIV SW1 1.8V/1A 1µF 24.9k 18.2k DA1 22µF FB1 GND 20k 3504 TA01a fSW = 1MHz 3504fa For more information www.linear.com/LT3504 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts
FeaTures DescripTion
n
Wide Input Range: 3.2V to 40V
The LT®3504 consists of four 1A output current buck n
Four 1A Outputs
regulators. The LT3504 has a wide operating input range n
100% Duty Cycle Operation
of 3.2V to 40V. An on-chip boost regulator allows each n
Resistor-Programmed Constant Frequency
channel to operate up to 100% duty cycle and eliminates n
Short-Circuit Robust the need for four external charge pump circuits. The LT3504 n Wide SYNC Range: 350kHz to 2.2MHz is designed to minimize external component count and n Anti-Phase Switching Reduces Ripple results in a simple and small application circuit. n 800mV FB Voltage The LT3504 operates robustly in fault conditions. Cycle- n Independent Run/Soft-Start Pins by-cycle peak current limit and catch diode current limit n Shutdown with UVLO sensing protect the part during overload conditions. Ther- n Internal Compensation mal shutdown protects the power switches at elevated n Thermal Shutdown temperatures. Soft-start helps keep the peak inductor n Tiny 28-Lead (4mm × 5mm) Thermally Enhanced current under control during startup. QFN Package The LT3504 also features output voltage tracking and
applicaTions
sequencing, programmable frequency, programmable undervoltage lockout, and a power good pin to indicate n Automotive Battery Regulation when all outputs are in regulation. n Industrial Control Supplies L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks n Wall Transformer Regulation of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Distributed Supply Regulation
Typical applicaTion Quad Buck Regulator in 4 × 5 QFN LT3504 Start-Up and Shutdown Waveform. VIN (Top Trace) Is Ramped
10µH SW4 5V/1A
from 0V Up to 8V and Then Back Down
52.3k 10µF
to 0V. The Other Four Traces Are the
DA4 SKY FB4
Output Voltages of All Four Channels
LT3504 10k 1µF 10µH 6.8µH VIN 5.4V to 20V SW5 V SW3 3.3V/1A IN 1V/DIV TRANSIENT TO 40V 5V CHANNEL BEGINS 10µF 100% DC OPERATION EN/UVLO DA3 31.6k VIN FB3 3.3V CHANNEL BEGINS CH4 1V/DIV VIN 10k 100% DC OPERATION VIN VIN 4.7µH CH3 1V/DIV RUN/SS1 SW2 UVLO = ~2.9V 2.5V/1A PARTS SHUTS RUN/SS2 CH2 1V/DIV 1µF 22.1k OFF RUN/SS3 DA2 22µF CH1 1V/DIV RUN/SS4 FB2 50nF 10k RT/SYNC 3.3µH 3504 TA01b 100ms/DIV SW1 1.8V/1A 1µF 24.9k 18.2k DA1 22µF FB1 GND 20k 3504 TA01a fSW = 1MHz 3504fa For more information www.linear.com/LT3504 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts
