Datasheet LTC3809-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | No RSENSE , Low Input Voltage, Synchronous DC/DC Controller with Output Tracking |
| Pages / Page | 24 / 1 — FEATURES. DESCRIPTION. Programmable Output Voltage Tracking. No Current … |
| File Format / Size | PDF / 267 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Programmable Output Voltage Tracking. No Current Sense Resistor Required
Model Line for this Datasheet
Text Version of Document
LTC3809-1 No R TM SENSE , Low Input Voltage, Synchronous DC/DC Controller with Output Tracking
FEATURES DESCRIPTION
n
Programmable Output Voltage Tracking
The LTC®3809-1 is a synchronous step-down switching n
No Current Sense Resistor Required
regulator controller that drives external complementary n
Constant Frequency Current Mode Operation for
power MOSFETs using few external components. The
Excellent Line and Load Transient Response
constant frequency current mode architecture with MOSFET n Wide VIN Range: 2.75V to 9.8V VDS sensing eliminates the need for a current sense resistor n Wide VOUT Range: 0.6V to VIN and improves effi ciency. n 0.6V ±1.5% Reference Optional Burst Mode operation provides high effi ciency n Low Dropout Operation: 100% Duty Cycle operation at light loads. 100% duty cycle provides low n Selectable Burst Mode®/Pulse-Skipping/Forced dropout operation, extending operating time in battery- Continuous Operation powered systems. Burst Mode is inhibited when the MODE n Auxiliary Winding Regulation pin is pulled low to reduce noise and RF interference. n Internal Soft-Start Circuitry n Selectable Maximum Peak Current Sense Threshold The LTC3809-1 allows either coincident or ratiometric n Output Overvoltage Protection output voltage tracking. Switching frequency is fi xed at n Micropower Shutdown: I 550kHz. Fault protection is provided by an overvoltage Q = 9μA n Tiny Thermally Enhanced Leadless (3mm × 3mm) comparator and a short-circuit current limit comparator. DFN and 10-lead MSOP Packages The LTC3809-1 is available in tiny footprint thermally enhanced DFN and 10-lead MSOP packages.
APPLICATIONS
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst n is a registered trademark of Linear Technology Corporation. No R 1- or 2-Cell Lithium-Ion Powered Devices SENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective n Notebook and Palmtop Computers, PDAs owners. Protected by U.S. Patents including 5481178, 5929620, 6580258, 6304066, 5847554, 6611131, 6498466. Other Patents pending. n Portable Instruments n Distributed DC Power Systems
TYPICAL APPLICATION Effi ciency and Power Loss vs Load Current High Effi ciency, 550kHz Step-Down Converter
100 10k VIN EFFICIENCY 2.75V TO 9.8V V 10μF IN = 3.3V V 90 1k IN IPRG POWER LOSS (mW) VIN = 5V VIN = 4.2V MODE 80 100 TG 59k LTC3809-1 2.2μH VOUT V TYPICAL POWER FB SW 2.5V 15k 70 10 2A LOSS (VIN = 4.2V) EFFICIENCY (%) I BG TH 47μF 187k 470pF RUN 60 1 GND FIGURE 8 CIRCUIT VOUT = 2.5V 38091 TA01 50 0.1 1 10 100 1k 10k LOAD CURRENT (mA) 38091 TA02 38091fc 1
FEATURES DESCRIPTION
n
Programmable Output Voltage Tracking
The LTC®3809-1 is a synchronous step-down switching n
No Current Sense Resistor Required
regulator controller that drives external complementary n
Constant Frequency Current Mode Operation for
power MOSFETs using few external components. The
Excellent Line and Load Transient Response
constant frequency current mode architecture with MOSFET n Wide VIN Range: 2.75V to 9.8V VDS sensing eliminates the need for a current sense resistor n Wide VOUT Range: 0.6V to VIN and improves effi ciency. n 0.6V ±1.5% Reference Optional Burst Mode operation provides high effi ciency n Low Dropout Operation: 100% Duty Cycle operation at light loads. 100% duty cycle provides low n Selectable Burst Mode®/Pulse-Skipping/Forced dropout operation, extending operating time in battery- Continuous Operation powered systems. Burst Mode is inhibited when the MODE n Auxiliary Winding Regulation pin is pulled low to reduce noise and RF interference. n Internal Soft-Start Circuitry n Selectable Maximum Peak Current Sense Threshold The LTC3809-1 allows either coincident or ratiometric n Output Overvoltage Protection output voltage tracking. Switching frequency is fi xed at n Micropower Shutdown: I 550kHz. Fault protection is provided by an overvoltage Q = 9μA n Tiny Thermally Enhanced Leadless (3mm × 3mm) comparator and a short-circuit current limit comparator. DFN and 10-lead MSOP Packages The LTC3809-1 is available in tiny footprint thermally enhanced DFN and 10-lead MSOP packages.
APPLICATIONS
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst n is a registered trademark of Linear Technology Corporation. No R 1- or 2-Cell Lithium-Ion Powered Devices SENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective n Notebook and Palmtop Computers, PDAs owners. Protected by U.S. Patents including 5481178, 5929620, 6580258, 6304066, 5847554, 6611131, 6498466. Other Patents pending. n Portable Instruments n Distributed DC Power Systems
TYPICAL APPLICATION Effi ciency and Power Loss vs Load Current High Effi ciency, 550kHz Step-Down Converter
100 10k VIN EFFICIENCY 2.75V TO 9.8V V 10μF IN = 3.3V V 90 1k IN IPRG POWER LOSS (mW) VIN = 5V VIN = 4.2V MODE 80 100 TG 59k LTC3809-1 2.2μH VOUT V TYPICAL POWER FB SW 2.5V 15k 70 10 2A LOSS (VIN = 4.2V) EFFICIENCY (%) I BG TH 47μF 187k 470pF RUN 60 1 GND FIGURE 8 CIRCUIT VOUT = 2.5V 38091 TA01 50 0.1 1 10 100 1k 10k LOAD CURRENT (mA) 38091 TA02 38091fc 1
