Datasheet LTC3879 (Analog Devices)
| 制造商 | Analog Devices |
| 描述 | Fast, Wide Operating Range No RSENSE Step-Down Controller |
| 页数 / 页 | 28 / 1 — FEATURES. DESCRIPTION. Wide VIN Range: 4V to 38V. ±1% 0.6V Voltage … |
| 文件格式/大小 | PDF / 314 Kb |
| 文件语言 | 英语 |
FEATURES. DESCRIPTION. Wide VIN Range: 4V to 38V. ±1% 0.6V Voltage Reference. Extremely Fast Transient Response. tON(MIN): 43ns
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LTC3879 Fast, Wide Operating Range No RSENSE Step-Down Controller
FEATURES DESCRIPTION
n
Wide VIN Range: 4V to 38V
The LTC®3879 is a synchronous step-down switching n
±1% 0.6V Voltage Reference
regulator controller optimized for high switching frequency n
Extremely Fast Transient Response
and fast transient response. The constant on-time valley n
tON(MIN): 43ns
current mode architecture allows for a wide input range, n
No RSENSE™ Valley Current Mode Control
including very low duty factor operation. No external sense n
Stable with Low ESR Ceramic COUT
resistor or slope compensation is required. System fl ex- n
Supports Smooth Start-Up in Pre-Biased Output
ibility is offered through a user-programmable soft-start pin n
Optimized for High Step-Down Ratios
and independent RUN pin. The voltage ramping soft-start n
Adjustable Output Voltage Soft-Start or Tracking
function can be programmed with a capacitor or made to n Power Good Output Voltage Monitor track an external reference source. n Dual N-Channel MOSFET Synchronous Drive Operating frequency is set by an external resistor and n Adjustable Switching Frequency compensated for variations in V n IN to offer excellent line Programmable Current Limit with Foldback stability. Discontinuous mode operation provides high n Output Overvoltage Protection effi ciency during light load conditions. A forced continu- n 16-Pin MSOP and 3mm × 3mm QFN Packages ous control pin allows the user to reduce noise and RF
APPLICATIONS
interference. Safety features include output overvoltage protection and programmable current limit with foldback. n Distributed Power Systems The current limit is user programmable. n Embedded Computing The LTC3879 allows operation from 4V to 38V at the input n Communications Infrastructure and from 0.6V to 90% VIN at the output. The LTC3879 is L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. available in a small 16-pin thermally enhanced MSOP or No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. 3mm × 3mm QFN packages. Protected by U.S. Patents, including 5481178, 6100678, 6580258, 5847554, 6304066.
TYPICAL APPLICATION High Effi ciency Step-Down Converter Effi ciency vs Load Current
432k 100 0.1μF RUN ION V 90 DISCONTINUOUS TRACK/SS V IN IN 4.5V TO 28V MODE 80 220pF TG RJK0305 10μF 27k LTC3879 70 ITH SW 0.56μH VOUT SGND BOOST 1.2V 60 CONTINUOUS MODE MODE 15A 0.22μF 50 INTVCC 330μF 40 BG RJK0330 s2 EFFICIENCY (%) 4.7μF 30 PGOOD PGND V 20 IN = 12V 10k VOUT = 1.2V 10 SW FREQ = 400kHz VRNG VFB FIGURE 10 CIRCUIT 0 10k 0.01 0.1 1 10 100 LOAD CURRENT (A) 3879 TA01a 3879 TA01b 3879f 1
FEATURES DESCRIPTION
n
Wide VIN Range: 4V to 38V
The LTC®3879 is a synchronous step-down switching n
±1% 0.6V Voltage Reference
regulator controller optimized for high switching frequency n
Extremely Fast Transient Response
and fast transient response. The constant on-time valley n
tON(MIN): 43ns
current mode architecture allows for a wide input range, n
No RSENSE™ Valley Current Mode Control
including very low duty factor operation. No external sense n
Stable with Low ESR Ceramic COUT
resistor or slope compensation is required. System fl ex- n
Supports Smooth Start-Up in Pre-Biased Output
ibility is offered through a user-programmable soft-start pin n
Optimized for High Step-Down Ratios
and independent RUN pin. The voltage ramping soft-start n
Adjustable Output Voltage Soft-Start or Tracking
function can be programmed with a capacitor or made to n Power Good Output Voltage Monitor track an external reference source. n Dual N-Channel MOSFET Synchronous Drive Operating frequency is set by an external resistor and n Adjustable Switching Frequency compensated for variations in V n IN to offer excellent line Programmable Current Limit with Foldback stability. Discontinuous mode operation provides high n Output Overvoltage Protection effi ciency during light load conditions. A forced continu- n 16-Pin MSOP and 3mm × 3mm QFN Packages ous control pin allows the user to reduce noise and RF
APPLICATIONS
interference. Safety features include output overvoltage protection and programmable current limit with foldback. n Distributed Power Systems The current limit is user programmable. n Embedded Computing The LTC3879 allows operation from 4V to 38V at the input n Communications Infrastructure and from 0.6V to 90% VIN at the output. The LTC3879 is L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. available in a small 16-pin thermally enhanced MSOP or No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. 3mm × 3mm QFN packages. Protected by U.S. Patents, including 5481178, 6100678, 6580258, 5847554, 6304066.
TYPICAL APPLICATION High Effi ciency Step-Down Converter Effi ciency vs Load Current
432k 100 0.1μF RUN ION V 90 DISCONTINUOUS TRACK/SS V IN IN 4.5V TO 28V MODE 80 220pF TG RJK0305 10μF 27k LTC3879 70 ITH SW 0.56μH VOUT SGND BOOST 1.2V 60 CONTINUOUS MODE MODE 15A 0.22μF 50 INTVCC 330μF 40 BG RJK0330 s2 EFFICIENCY (%) 4.7μF 30 PGOOD PGND V 20 IN = 12V 10k VOUT = 1.2V 10 SW FREQ = 400kHz VRNG VFB FIGURE 10 CIRCUIT 0 10k 0.01 0.1 1 10 100 LOAD CURRENT (A) 3879 TA01a 3879 TA01b 3879f 1