Datasheet LTC3672B-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Monolithic Fixed-Output 400mA Buck Regulator with Dual 150mA LDOs in 2mm x 2mm DFN |
| Pages / Page | 12 / 1 — FEATURES. DESCRIPTION. Triple Output Supply From a Single 2.9V to 5.5V … |
| File Format / Size | PDF / 176 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Triple Output Supply From a Single 2.9V to 5.5V Input. Buck DC/DC: Fixed 1.8V Output, Up to 400mA
Model Line for this Datasheet
Text Version of Document
LTC3672B-1 Monolithic Fixed-Output 400mA Buck Regulator with Dual 150mA LDOs in 2mm × 2mm DFN
FEATURES DESCRIPTION
■
Triple Output Supply From a Single 2.9V to 5.5V Input
The LTC®3672B-1 is a triple power supply composed of a ■
Buck DC/DC: Fixed 1.8V Output, Up to 400mA
400mA synchronous buck regulator and two 150mA low- ■
LDO1: Fixed 1.2V Output, Up to 150mA
dropout linear regulators (LDOs), where one of the LDOs ■
LDO2: Fixed 2.8V Output, Up to 150mA
can be powered from the buck output to improve effi ciency. ■
±2.5% Reference Accuracy
Constant-frequency 2.25MHz operation is maintained ■
Constant Frequency 2.25MHz Operation
down to very light loads. The input supply range of 2.9V ■ Minimum External Component Count to 5.5V is especially well-suited for single-cell Lithium-Ion ■ Current Mode Operation for Excellent Line and Load and Lithium-Polymer applications, and for powering low Transient Response voltage ASICs from 3.3V or 5V rails. ■ Internal Soft-Start for Each Output The LTC3672B-1 regulates 1.8V at the buck output, 1.2V ■ Single Enable Pin Turns On/Shuts Down All Three at the LDO1 output, and 2.8V at the LDO2 output. Exter- Outputs nal component count is minimal—all that is needed is a ■ Tiny 2mm × 2mm × 0.75mm DFN Package single inductor, an input capacitor, and output capacitors for each of the three outputs. Control loop compensation
APPLICATIONS
is internal to the LTC3672B-1. ■ DMB Cellphones The LTC3672B-1 is available in a 2mm × 2mm × 0.75mm ■ Handheld Products (PDA, PMP, GPS) 8-Lead DFN package. ■ Multivoltage Power for Digital Logic, I/O, FPGAs, L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other CPLDs, ASICs, CPUs, and RF Chipsets trademarks are the property of their respective owners.
TYPICAL APPLICATION Buck DC/DC Effi ciency vs Load
100 VIN 2.9V TO 5.5V 95 VIN = 2.9V 90 4.7MH V V OUT1 IN = 3.6V 2.2MF VIN SW 1.8V 85 400mA 10MF GND BUCKOUT (250mA IF LDO1 V 80 IN = 5.5V FULLY-LOADED) VIN1 V EFFICIENCY (%) 75 OUT2 ENABLE LDO1 1.2V ENALL 70 INPUT 150mA 1MF LTC3672B-1 65 VOUT3 LDO2 2.8V 60 UP TO 150mA 3672b1 TA01 1MF 0 50 100 150 200 250 300 350 400 (SUBJECT TO DROPOUT ILOAD (mA) LIMITATIONS) 3672b1 TA01b 3672B1f 1
FEATURES DESCRIPTION
■
Triple Output Supply From a Single 2.9V to 5.5V Input
The LTC®3672B-1 is a triple power supply composed of a ■
Buck DC/DC: Fixed 1.8V Output, Up to 400mA
400mA synchronous buck regulator and two 150mA low- ■
LDO1: Fixed 1.2V Output, Up to 150mA
dropout linear regulators (LDOs), where one of the LDOs ■
LDO2: Fixed 2.8V Output, Up to 150mA
can be powered from the buck output to improve effi ciency. ■
±2.5% Reference Accuracy
Constant-frequency 2.25MHz operation is maintained ■
Constant Frequency 2.25MHz Operation
down to very light loads. The input supply range of 2.9V ■ Minimum External Component Count to 5.5V is especially well-suited for single-cell Lithium-Ion ■ Current Mode Operation for Excellent Line and Load and Lithium-Polymer applications, and for powering low Transient Response voltage ASICs from 3.3V or 5V rails. ■ Internal Soft-Start for Each Output The LTC3672B-1 regulates 1.8V at the buck output, 1.2V ■ Single Enable Pin Turns On/Shuts Down All Three at the LDO1 output, and 2.8V at the LDO2 output. Exter- Outputs nal component count is minimal—all that is needed is a ■ Tiny 2mm × 2mm × 0.75mm DFN Package single inductor, an input capacitor, and output capacitors for each of the three outputs. Control loop compensation
APPLICATIONS
is internal to the LTC3672B-1. ■ DMB Cellphones The LTC3672B-1 is available in a 2mm × 2mm × 0.75mm ■ Handheld Products (PDA, PMP, GPS) 8-Lead DFN package. ■ Multivoltage Power for Digital Logic, I/O, FPGAs, L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other CPLDs, ASICs, CPUs, and RF Chipsets trademarks are the property of their respective owners.
TYPICAL APPLICATION Buck DC/DC Effi ciency vs Load
100 VIN 2.9V TO 5.5V 95 VIN = 2.9V 90 4.7MH V V OUT1 IN = 3.6V 2.2MF VIN SW 1.8V 85 400mA 10MF GND BUCKOUT (250mA IF LDO1 V 80 IN = 5.5V FULLY-LOADED) VIN1 V EFFICIENCY (%) 75 OUT2 ENABLE LDO1 1.2V ENALL 70 INPUT 150mA 1MF LTC3672B-1 65 VOUT3 LDO2 2.8V 60 UP TO 150mA 3672b1 TA01 1MF 0 50 100 150 200 250 300 350 400 (SUBJECT TO DROPOUT ILOAD (mA) LIMITATIONS) 3672b1 TA01b 3672B1f 1
