Datasheet LT3500 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller |
| Pages / Page | 28 / 1 — FEATURES. DESCRIPTION. Wide Input Range: 3V to 36V Operating,. 40V … |
| File Format / Size | PDF / 331 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Wide Input Range: 3V to 36V Operating,. 40V Maximum. Short-Circuit Protected Over Full Input Range
Model Line for this Datasheet
Text Version of Document
LT3500 Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller
FEATURES DESCRIPTION
n
Wide Input Range: 3V to 36V Operating,
The LT®3500 is a current mode PWM step-down DC/DC
40V Maximum
converter with an internal 2.3A switch. The wide input range n
Short-Circuit Protected Over Full Input Range
of 3V to 40V makes the LT3500 suitable for regulating n
2A Output Current Capability
power from a wide variety of sources, including automo- n
Adjustable/Synchronizable Fixed Frequency
tive batteries, 24V industrial supplies and unregulated
Operation from 250kHz to 2.2MHz
wall adapters. n
Soft-Start/Tracking Capability
Resistor-programmable 250kHz to 2.2MHz frequency n
Output Adjustable Down to 0.8V
range and synchronization capability enable optimization n
Adjustable Linear Regulator/Driver with 13mA
between effi ciency and external component size. Cycle-
Output Capability
by-cycle current limit, frequency foldback and thermal n
Power Good Comparator with Complimentary
shutdown provide protection against a shorted output.
Outputs
The soft-start feature controls the ramp rate of the output n Low Shutdown Current: 12μA voltage, eliminating input current surge during start-up, n Thermally Enhanced 3mm × 3mm DFN or 16-Pin and also provides output tracking. MSOP Package The LT3500 contains an internal NPN transistor with feed-
APPLICATIONS
back control which can be confi gured as a linear regulator or as a linear regulator controller. n Automotive Battery Regulation n Industrial Control The LT3500’s low current shutdown mode (<12μA) enables n Wall Transformer Regulation easy power management in battery-powered systems. n Distributed Power Regulation L, LT, LTC, LTM, 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 Dual Step-Down Converters Switching Converter Effi ciency Output Voltage Ripple
90 VIN V BST 6V TO 36V IN 0.47μF 85 2.2μF LT3500 6.8μH VOUT1 80 SW 5V VOUT1 = 5V AT 1A 1A AC COUPLED B240A SHDN 75 2mV/DIV 42.2k SS 22μF 0.47μF FB 70 PG 8.06k 65 PG EFFICIENCY (%) VOUT2 = 3.3V AT 1A 60 AC COUPLED RT/SYNC LDRV 2mV/DIV VIN = 12V 53.6k VC 55 1k IOUT2 = 0A 330pF 24.9k VOUT2 FREQUENCY = 800kHz LFB 3.3V 50 500ns/DIV 3500 TA01c 40.2k 1A 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 8.06k 22μF LOAD CURRENT (A) 3500 TA01b 3500 TA01a 3500fc 1
FEATURES DESCRIPTION
n
Wide Input Range: 3V to 36V Operating,
The LT®3500 is a current mode PWM step-down DC/DC
40V Maximum
converter with an internal 2.3A switch. The wide input range n
Short-Circuit Protected Over Full Input Range
of 3V to 40V makes the LT3500 suitable for regulating n
2A Output Current Capability
power from a wide variety of sources, including automo- n
Adjustable/Synchronizable Fixed Frequency
tive batteries, 24V industrial supplies and unregulated
Operation from 250kHz to 2.2MHz
wall adapters. n
Soft-Start/Tracking Capability
Resistor-programmable 250kHz to 2.2MHz frequency n
Output Adjustable Down to 0.8V
range and synchronization capability enable optimization n
Adjustable Linear Regulator/Driver with 13mA
between effi ciency and external component size. Cycle-
Output Capability
by-cycle current limit, frequency foldback and thermal n
Power Good Comparator with Complimentary
shutdown provide protection against a shorted output.
Outputs
The soft-start feature controls the ramp rate of the output n Low Shutdown Current: 12μA voltage, eliminating input current surge during start-up, n Thermally Enhanced 3mm × 3mm DFN or 16-Pin and also provides output tracking. MSOP Package The LT3500 contains an internal NPN transistor with feed-
APPLICATIONS
back control which can be confi gured as a linear regulator or as a linear regulator controller. n Automotive Battery Regulation n Industrial Control The LT3500’s low current shutdown mode (<12μA) enables n Wall Transformer Regulation easy power management in battery-powered systems. n Distributed Power Regulation L, LT, LTC, LTM, 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 Dual Step-Down Converters Switching Converter Effi ciency Output Voltage Ripple
90 VIN V BST 6V TO 36V IN 0.47μF 85 2.2μF LT3500 6.8μH VOUT1 80 SW 5V VOUT1 = 5V AT 1A 1A AC COUPLED B240A SHDN 75 2mV/DIV 42.2k SS 22μF 0.47μF FB 70 PG 8.06k 65 PG EFFICIENCY (%) VOUT2 = 3.3V AT 1A 60 AC COUPLED RT/SYNC LDRV 2mV/DIV VIN = 12V 53.6k VC 55 1k IOUT2 = 0A 330pF 24.9k VOUT2 FREQUENCY = 800kHz LFB 3.3V 50 500ns/DIV 3500 TA01c 40.2k 1A 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 8.06k 22μF LOAD CURRENT (A) 3500 TA01b 3500 TA01a 3500fc 1
