Datasheet LTC1871-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Wide Input Range, No RSENSE Current Mode Boost, Flyback and SEPIC Controller |
| Pages / Page | 36 / 1 — FEATURES. DESCRIPTION. High Effi ciency (No Sense Resistor Required). Wide … |
| File Format / Size | PDF / 538 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. High Effi ciency (No Sense Resistor Required). Wide Input Voltage Range: 2.5V to 36V
Model Line for this Datasheet
Text Version of Document
LTC1871-1 Wide Input Range, No RSENSE™ Current Mode Boost, Flyback and SEPIC Controller
FEATURES DESCRIPTION
n
High Effi ciency (No Sense Resistor Required)
The LTC®1871-1 is a wide input range, current mode, boost, n
Wide Input Voltage Range: 2.5V to 36V
fl yback or SEPIC controller that drives an N-channel power n
Current Mode Control Provides Excellent
MOSFET and requires very few external components. It
Transient Response
eliminates the need for a current sense resistor by utilizing n
High Maximum Duty Cycle (92% Typ)
the power MOSFET’s on-resistance, thereby maximizing n
±2% RUN Pin Threshold with 100mV Hysteresis
effi ciency. Higher output voltage applications are possible n
±1% Internal Voltage Reference
with the LTC1871-1 by connecting the SENSE pin to a n
Ultra Low Pulse Skip Threshold for Wide Input
resistor in the source of the power MOSFET.
Range Applications
The IC’s operating frequency can be set with an external n Micropower Shutdown: IQ = 10μA resistor over a 50kHz to 1MHz range, and can be synchro- n Programmable Operating Frequency nized to an external clock using the MODE/SYNC pin. (50kHz to 1MHz) with One External Resistor n Synchronizable to an External Clock Up to 1.3 × f The LTC1871-1 differs from the LTC1871 by having a OSC n User-Controlled Pulse Skip or Burst Mode® Operation lower pulse skip threshold, making it ideal for applica- n Internal 5.2V Low Dropout Voltage Regulator tions requiring constant frequency operation at light n Output Overvoltage Protection loads. The lower pulse skip threshold also helps maintain n Capable of Operating with a Sense Resistor for High constant frequency operation in applications with a wide Output Voltage Applications input voltage range. For applications requiring primary- n Small 10-Lead MSOP Package to-secondary side isolation, please refer to the LTC1871 datasheet.
APPLICATIONS
The LTC1871-1 is available in the 10-lead MSOP package. L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. n Telecom Power Supplies No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the n Portable Electronic Equipment property of their respective owners.
TYPICAL APPLICATION
VIN 3.3V
Effi ciency of Figure 1
L1 100 1μH D1 90 RUN SENSE VOUT Burst Mode 5V 80 OPERATION ITH VIN 7A RC C LTC1871-1 OUT1 + (10A PEAK) 70 22k 150μF PULSE-SKIP FB INTV 6.3V CC C MODE C1 R1 ×4 COUT2 60 6.8nF 12.1k FREQ GATE M1 22μF EFFICIENCY (%) 1% CIN R2 R CVCC + 6.3V C T MODE/SYNC GND 22μF 50 C2 37.4k 80.6k 4.7μF X5R 47pF 6.3V 1% 1% X5R ×2 ×2 GND 40 18711 F01a 30 CIN: TAIYO YUDEN JMK325BJ226MM D1: MBRB2515L 0.001 0.01 0.1 1 10 COUT1: PANASONIC EEFUEOJ151R L1: SUMIDA CEP125-H 1R0MH OUTPUT CURRENT (A) COUT2: TAIYO YUDEN JMK325BJ226MM M1: FAIRCHILD FDS7760A 18711 F01b
Figure 1. High Effi ciency 3.3V Input, 5V Output Boost Converter (Bootstrapped)
18711fb 1
FEATURES DESCRIPTION
n
High Effi ciency (No Sense Resistor Required)
The LTC®1871-1 is a wide input range, current mode, boost, n
Wide Input Voltage Range: 2.5V to 36V
fl yback or SEPIC controller that drives an N-channel power n
Current Mode Control Provides Excellent
MOSFET and requires very few external components. It
Transient Response
eliminates the need for a current sense resistor by utilizing n
High Maximum Duty Cycle (92% Typ)
the power MOSFET’s on-resistance, thereby maximizing n
±2% RUN Pin Threshold with 100mV Hysteresis
effi ciency. Higher output voltage applications are possible n
±1% Internal Voltage Reference
with the LTC1871-1 by connecting the SENSE pin to a n
Ultra Low Pulse Skip Threshold for Wide Input
resistor in the source of the power MOSFET.
Range Applications
The IC’s operating frequency can be set with an external n Micropower Shutdown: IQ = 10μA resistor over a 50kHz to 1MHz range, and can be synchro- n Programmable Operating Frequency nized to an external clock using the MODE/SYNC pin. (50kHz to 1MHz) with One External Resistor n Synchronizable to an External Clock Up to 1.3 × f The LTC1871-1 differs from the LTC1871 by having a OSC n User-Controlled Pulse Skip or Burst Mode® Operation lower pulse skip threshold, making it ideal for applica- n Internal 5.2V Low Dropout Voltage Regulator tions requiring constant frequency operation at light n Output Overvoltage Protection loads. The lower pulse skip threshold also helps maintain n Capable of Operating with a Sense Resistor for High constant frequency operation in applications with a wide Output Voltage Applications input voltage range. For applications requiring primary- n Small 10-Lead MSOP Package to-secondary side isolation, please refer to the LTC1871 datasheet.
APPLICATIONS
The LTC1871-1 is available in the 10-lead MSOP package. L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. n Telecom Power Supplies No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the n Portable Electronic Equipment property of their respective owners.
TYPICAL APPLICATION
VIN 3.3V
Effi ciency of Figure 1
L1 100 1μH D1 90 RUN SENSE VOUT Burst Mode 5V 80 OPERATION ITH VIN 7A RC C LTC1871-1 OUT1 + (10A PEAK) 70 22k 150μF PULSE-SKIP FB INTV 6.3V CC C MODE C1 R1 ×4 COUT2 60 6.8nF 12.1k FREQ GATE M1 22μF EFFICIENCY (%) 1% CIN R2 R CVCC + 6.3V C T MODE/SYNC GND 22μF 50 C2 37.4k 80.6k 4.7μF X5R 47pF 6.3V 1% 1% X5R ×2 ×2 GND 40 18711 F01a 30 CIN: TAIYO YUDEN JMK325BJ226MM D1: MBRB2515L 0.001 0.01 0.1 1 10 COUT1: PANASONIC EEFUEOJ151R L1: SUMIDA CEP125-H 1R0MH OUTPUT CURRENT (A) COUT2: TAIYO YUDEN JMK325BJ226MM M1: FAIRCHILD FDS7760A 18711 F01b
Figure 1. High Effi ciency 3.3V Input, 5V Output Boost Converter (Bootstrapped)
18711fb 1
