Datasheet LT3508 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual Monolithic 1.4A Step-Down Switching Regulator |
| Pages / Page | 26 / 1 — FEATURES. DESCRIPTION. Wide Input Voltage Range: 3.7V to 36V. Two 1.4A … |
| File Format / Size | PDF / 322 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Wide Input Voltage Range: 3.7V to 36V. Two 1.4A Output Switching Regulators with Internal
Text Version of Document
LT3508 Dual Monolithic 1.4A Step-Down Switching Regulator
FEATURES DESCRIPTION
n
Wide Input Voltage Range: 3.7V to 36V
The LT®3508 is a dual current mode PWM step-down n
Two 1.4A Output Switching Regulators with Internal
DC/DC converter with internal power switches capable of
Power Switches
generating two 1.4A outputs. The wide input voltage range n
Adjustable 250kHz to 2.5MHz Switching Frequency
of 3.7V to 36V makes the LT3508 suitable for regulating n
Synchronizable over the Full Frequency Range
power from a wide variety of sources, including automo- n Anti-Phase Switching Reduces Ripple tive batteries, 24V industrial supplies and unregulated wall n Uses Small Inductors and Ceramic Capacitors adapters. Both converters are synchronized to a single os- n Accurate Programmable Undervoltage Lockout cillator programmable up to 2.5MHz and run with opposite n Independent Tracking, Soft-Start and Power Good phases, reducing input ripple current. Its high operating Circuits Ease Supply Sequencing frequency allows the use of small, low cost inductors and n Output Adjustable Down to 800mV ceramic capacitors, resulting in low, predictable output n Small 4mm × 4mm 24-Pin QFN or 16-Pin Thermally ripple. Each regulator has independent tracking and soft- Enhanced TSSOP Surface Mount Packages start circuits and generates a power good signal when its output is in regulation, easing power supply sequencing
APPLICATIONS
and interfacing with microcontrollers and DSPs. Cycle-by-cycle current limit, frequency foldback and ther- n Automotive mal shutdown provide protection against shorted outputs, n DSP Power Supplies and soft-start eliminates input current surge during start- n Wall Transformer Regulation up. The low current (<2μA) shutdown mode enables easy n DSL and Cable Modems power management in battery-powered systems. n PCI Express L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION 3.3V and 5V Dual Output Step-Down Converter with Output Sequencing
VIN ON OFF 5.6V TO 36V
Effi ciency
4.7μF VIN1 VIN2 SHDN 95 OUT2 VIN = 12V BOOST1 BOOST2 5V V 1.4A 90 OUT2 = 5V 0.22μF 0.22μF 6.8μH OUT1 10μH 3.3V SW1 SW2 V 1.4A 85 OUT1 = 3.3V LT3508 35.7k 56.2k 80 FB1 FB2 VC1 VC2 EFFICIENCY (%) 75 11.5k 51k TRACK/SS1 PG1 43k 10.7k 10μF TRACK/SS2 PG2 70 22μF 150pF GND RT/SYNC 100k 65 1nF 52.3k 100pF 0 0.5 1 1.5 LOAD CURRENT (A) POWER fSW = 700kHz 3508 TA01a GOOD 3508 TA01b 3508fd 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 TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
FEATURES DESCRIPTION
n
Wide Input Voltage Range: 3.7V to 36V
The LT®3508 is a dual current mode PWM step-down n
Two 1.4A Output Switching Regulators with Internal
DC/DC converter with internal power switches capable of
Power Switches
generating two 1.4A outputs. The wide input voltage range n
Adjustable 250kHz to 2.5MHz Switching Frequency
of 3.7V to 36V makes the LT3508 suitable for regulating n
Synchronizable over the Full Frequency Range
power from a wide variety of sources, including automo- n Anti-Phase Switching Reduces Ripple tive batteries, 24V industrial supplies and unregulated wall n Uses Small Inductors and Ceramic Capacitors adapters. Both converters are synchronized to a single os- n Accurate Programmable Undervoltage Lockout cillator programmable up to 2.5MHz and run with opposite n Independent Tracking, Soft-Start and Power Good phases, reducing input ripple current. Its high operating Circuits Ease Supply Sequencing frequency allows the use of small, low cost inductors and n Output Adjustable Down to 800mV ceramic capacitors, resulting in low, predictable output n Small 4mm × 4mm 24-Pin QFN or 16-Pin Thermally ripple. Each regulator has independent tracking and soft- Enhanced TSSOP Surface Mount Packages start circuits and generates a power good signal when its output is in regulation, easing power supply sequencing
APPLICATIONS
and interfacing with microcontrollers and DSPs. Cycle-by-cycle current limit, frequency foldback and ther- n Automotive mal shutdown provide protection against shorted outputs, n DSP Power Supplies and soft-start eliminates input current surge during start- n Wall Transformer Regulation up. The low current (<2μA) shutdown mode enables easy n DSL and Cable Modems power management in battery-powered systems. n PCI Express L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION 3.3V and 5V Dual Output Step-Down Converter with Output Sequencing
VIN ON OFF 5.6V TO 36V
Effi ciency
4.7μF VIN1 VIN2 SHDN 95 OUT2 VIN = 12V BOOST1 BOOST2 5V V 1.4A 90 OUT2 = 5V 0.22μF 0.22μF 6.8μH OUT1 10μH 3.3V SW1 SW2 V 1.4A 85 OUT1 = 3.3V LT3508 35.7k 56.2k 80 FB1 FB2 VC1 VC2 EFFICIENCY (%) 75 11.5k 51k TRACK/SS1 PG1 43k 10.7k 10μF TRACK/SS2 PG2 70 22μF 150pF GND RT/SYNC 100k 65 1nF 52.3k 100pF 0 0.5 1 1.5 LOAD CURRENT (A) POWER fSW = 700kHz 3508 TA01a GOOD 3508 TA01b 3508fd 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 TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
