Datasheet LT3507 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Triple Monolithic Step-Down Regulator with LDO |
| Pages / Page | 30 / 1 — Features. Description. Wide Input Range: 4V to 36V. One 2.4A and Two 1.5A … |
| File Format / Size | PDF / 395 Kb |
| Document Language | English |
Features. Description. Wide Input Range: 4V to 36V. One 2.4A and Two 1.5A Output Switching
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LT3507 Triple Monolithic Step-Down Regulator with LDO
Features Description
n
Wide Input Range: 4V to 36V
The LT®3507 is a triple, current mode, DC/DC converter n
One 2.4A and Two 1.5A Output Switching
with internal power switches and a low dropout regulator.
Regulators with Internal Power Switches
The switching converters are step-down converters capable n
Low Dropout Linear Regulator with External
of generating one 2.4A output and two 1.5A outputs. All
Transistor
three converters are synchronized to a single oscillator. n
Antiphase Switching Reduces Ripple
The 2.4A output runs with opposite phase to the other two n Independent Run, Tracking/Soft-Start, and Power converters, reducing input ripple current. Each regulator Good Indicators Ease Supply Sequencing has independent shutdown and soft-start circuits, and n Uses Small Inductors and Ceramic Capacitors generates a power good signal when its output is in regu- n Adjustable, 250kHz to 2.5MHz Switching Frequency, lation, easing power supply sequencing and interfacing Synchronizable Over the Full Range with microcontrollers and DSPs. n User Programmable Overvoltage and Undervoltage The switching frequency is set with a single resistor yielding Lockouts a range of 250kHz to 2.5MHz. The high switching frequency n Thermally Enhanced, 38-Lead 5mm × 7mm QFN allows the use of small inductors and capacitors resulting Package in a very small triple output supply. The constant switching
applications
frequency, combined with low impedance ceramic capaci- n tors, results in low, predictable output ripple. With its wide DSL and Cable Modems n input voltage range of 4V to 36V, the LT3507 regulates Distributed Power Regulation n a broad array of power sources including 5V logic rails, DSP Power n unregulated wall transformers, lead acid batteries and Automotive distributed power supplies. L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
typical application 5V, 3.3V, 2.5V and 1.8V Step-Down Regulator Start-Up Waveforms—Coincident Tracking
VIN 6V TO 36V 22µF VIN1 VIN2 VIN3 BOOST1 BOOST2 VOUT3 V 4.7µH 0.22µF OUT1 1.8V SW1 2.4A 0.22µF VOUT2 18.7k 1V/DIV V 10µH V OUT4 OUT2 100µF FB1 SW2 3.3V VOUT1 1.3A 15k 680pF 18.7k VC1 LT3507 35.7k 22µF VOUT2 FB2 BOOST3 V 15µH 0.22µF OUT3 1ms/DIV 3507 TA01b 5V 1000pF 11.5k SW3 1.5A 16.2k VC2 53.6k 22µF FB3 BIAS 10.2k 680pF 24.3k VC3 DRIVE 24.3k VOUT4 FB4 2.5V RT/SYNC 0.2A 107k GND 11.5k 2.2µF fSW = 450kHz 3507 TA01a 3507fb For more information www.linear.com/LT3507 1
Features Description
n
Wide Input Range: 4V to 36V
The LT®3507 is a triple, current mode, DC/DC converter n
One 2.4A and Two 1.5A Output Switching
with internal power switches and a low dropout regulator.
Regulators with Internal Power Switches
The switching converters are step-down converters capable n
Low Dropout Linear Regulator with External
of generating one 2.4A output and two 1.5A outputs. All
Transistor
three converters are synchronized to a single oscillator. n
Antiphase Switching Reduces Ripple
The 2.4A output runs with opposite phase to the other two n Independent Run, Tracking/Soft-Start, and Power converters, reducing input ripple current. Each regulator Good Indicators Ease Supply Sequencing has independent shutdown and soft-start circuits, and n Uses Small Inductors and Ceramic Capacitors generates a power good signal when its output is in regu- n Adjustable, 250kHz to 2.5MHz Switching Frequency, lation, easing power supply sequencing and interfacing Synchronizable Over the Full Range with microcontrollers and DSPs. n User Programmable Overvoltage and Undervoltage The switching frequency is set with a single resistor yielding Lockouts a range of 250kHz to 2.5MHz. The high switching frequency n Thermally Enhanced, 38-Lead 5mm × 7mm QFN allows the use of small inductors and capacitors resulting Package in a very small triple output supply. The constant switching
applications
frequency, combined with low impedance ceramic capaci- n tors, results in low, predictable output ripple. With its wide DSL and Cable Modems n input voltage range of 4V to 36V, the LT3507 regulates Distributed Power Regulation n a broad array of power sources including 5V logic rails, DSP Power n unregulated wall transformers, lead acid batteries and Automotive distributed power supplies. L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
typical application 5V, 3.3V, 2.5V and 1.8V Step-Down Regulator Start-Up Waveforms—Coincident Tracking
VIN 6V TO 36V 22µF VIN1 VIN2 VIN3 BOOST1 BOOST2 VOUT3 V 4.7µH 0.22µF OUT1 1.8V SW1 2.4A 0.22µF VOUT2 18.7k 1V/DIV V 10µH V OUT4 OUT2 100µF FB1 SW2 3.3V VOUT1 1.3A 15k 680pF 18.7k VC1 LT3507 35.7k 22µF VOUT2 FB2 BOOST3 V 15µH 0.22µF OUT3 1ms/DIV 3507 TA01b 5V 1000pF 11.5k SW3 1.5A 16.2k VC2 53.6k 22µF FB3 BIAS 10.2k 680pF 24.3k VC3 DRIVE 24.3k VOUT4 FB4 2.5V RT/SYNC 0.2A 107k GND 11.5k 2.2µF fSW = 450kHz 3507 TA01a 3507fb For more information www.linear.com/LT3507 1
