Datasheet LTC3875 (Analog Devices)
| 制造商 | Analog Devices |
| 描述 | Dual, 2-Phase, Synchronous Controller with Low Value DCR Sensing and Temperature Compensation |
| 页数 / 页 | 46 / 1 — FEATURES. DESCRIPTION. Low Value DCR Current Sensing. Programmable DCR … |
| 文件格式/大小 | PDF / 997 Kb |
| 文件语言 | 英语 |
FEATURES. DESCRIPTION. Low Value DCR Current Sensing. Programmable DCR Temperature Compensation
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LTC3875 Dual, 2-Phase, Synchronous Controller with Low Value DCR Sensing and Temperature Compensation
FEATURES DESCRIPTION
n
Low Value DCR Current Sensing
The LTC®3875 is a dual output current mode synchronous n
Programmable DCR Temperature Compensation
step-down DC/DC controller that drives all N-channel n
±0.5% 0.6V Output Voltage Accuracy
synchronous power MOSFET stages. It employs a unique n
Dual True Remote Sensing Differential Amplifiers
architecture which enhances the signal-to-noise ratio of n
Optional Fast Transient Operation
the current sense signal, allowing the use of very low DC n
Phase-Lockable Fixed Frequency 250kHz to 720kHz
resistance power inductors to maximize the efficiency in n
Dual, 180° Phased Controllers Reduce Required
high current applications. This feature also reduces the
Input Capacitance and Power Supply Induced Noise
switching jitter commonly found in low DCR applications. n Dual N-Channel MOSFET Synchronous Drive The LTC3875 features two high speed remote sense differ- n Wide VIN Range: 4.5V to 38V Operation ential amplifiers, programmable current sense limits from n Output Voltage Range with Low DCR: 0.6V to 3.5V, 10mV to 30mV and DCR temperature compensation to limit without Low DCR: 0.6V to 5V the maximum output current precisely over temperature. n Adjustable Soft-Start Current Ramping or Tracking n A unique thermal balancing function adjusts per phase cur- Foldback Output Current Limiting n rent in order to minimize the thermal stress for multichip Clock Input and Output for Up to 12-Phase Operation n single output applications. The LTC3875 also features a Short-Circuit Soft Recovery n precise 0.6V reference with guaranteed accuracy of ±0.5% Output Overvoltage Protection n that provides an accurate output voltage from 0.6V to 3.5V. Power Good Output Voltage Monitor n A 4.5V to 38V input voltage range allows it to support a 40-Lead QFN Packages wide variety of bus voltages. The LTC3875 is available
APPLICATIONS
in a low profile 40-lead 6mm × 6mm (0.5mm pitch) and 40-lead 5mm × 5mm (0.4mm pitch) QFN packages. n Servers and Instruments L, LT, LTC, LTM, Linear Technology, the Linear logo OPTI-LOOP, Burst Mode and PolyPhase n Telecom Systems are registered trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents n DC Power Distribution Systems including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258.
TYPICAL APPLICATION High Efficiency Dual Phase 1.2V/60A Step-Down Converter
VIN INTV 6V TO 14V
Efficiency and Power Loss
CC 22µF 4.7µF V 16V ×4 IN INTVCC PHASMD
vs Load Current
CLKOUT (OPTIONAL) RUN1,2 PGOOD (OPTIONAL) 100 14 THERMAL ILIM IFAST THERMAL 12VIN ENTMPB MODE/PLLIN SENSOR SENSOR 1.8V TG1 TG2 O 95 12 ~400kHz 0.3µH 0.3µH BOOST1 BOOST2 CCM (0.32mΩ DCR) (0.32mΩ DCR) 10 POWER LOSS (W) SW1 LTC3875 SW2 90 EXTVCC 8 BG1 BG2 TAVG 85 PGND TRSET1 6 TRSET2 SNSA1+ EFFICIENCY (%) SNSA2+ 80 SNS1– 4 SNS2– 0.32mΩ SNSD1+ SNSD2+ 75 1.5mΩ TCOMP1 2 TCOMP2 0.32mΩ PLOSS VOUT V + OSNS1 FREQ 20k VOUT 1.5mΩ PLOSS V – OSNS1 V + 1.2V 70 0 + OSNS2 ITH1 0 10 20 30 40 50 60 470µF V – OSNS2 60A 2.5V ×2 TK/SS1 TK/SS2 I 1500pF LOAD CURRENT (A) TH2 + SP 470µF 122k 15k 20k 2.5V ×2 3875 TA01b 0.1µF SP 3875 TA01a 3875fb For more information www.linear.com/LTC3875 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Related Parts
FEATURES DESCRIPTION
n
Low Value DCR Current Sensing
The LTC®3875 is a dual output current mode synchronous n
Programmable DCR Temperature Compensation
step-down DC/DC controller that drives all N-channel n
±0.5% 0.6V Output Voltage Accuracy
synchronous power MOSFET stages. It employs a unique n
Dual True Remote Sensing Differential Amplifiers
architecture which enhances the signal-to-noise ratio of n
Optional Fast Transient Operation
the current sense signal, allowing the use of very low DC n
Phase-Lockable Fixed Frequency 250kHz to 720kHz
resistance power inductors to maximize the efficiency in n
Dual, 180° Phased Controllers Reduce Required
high current applications. This feature also reduces the
Input Capacitance and Power Supply Induced Noise
switching jitter commonly found in low DCR applications. n Dual N-Channel MOSFET Synchronous Drive The LTC3875 features two high speed remote sense differ- n Wide VIN Range: 4.5V to 38V Operation ential amplifiers, programmable current sense limits from n Output Voltage Range with Low DCR: 0.6V to 3.5V, 10mV to 30mV and DCR temperature compensation to limit without Low DCR: 0.6V to 5V the maximum output current precisely over temperature. n Adjustable Soft-Start Current Ramping or Tracking n A unique thermal balancing function adjusts per phase cur- Foldback Output Current Limiting n rent in order to minimize the thermal stress for multichip Clock Input and Output for Up to 12-Phase Operation n single output applications. The LTC3875 also features a Short-Circuit Soft Recovery n precise 0.6V reference with guaranteed accuracy of ±0.5% Output Overvoltage Protection n that provides an accurate output voltage from 0.6V to 3.5V. Power Good Output Voltage Monitor n A 4.5V to 38V input voltage range allows it to support a 40-Lead QFN Packages wide variety of bus voltages. The LTC3875 is available
APPLICATIONS
in a low profile 40-lead 6mm × 6mm (0.5mm pitch) and 40-lead 5mm × 5mm (0.4mm pitch) QFN packages. n Servers and Instruments L, LT, LTC, LTM, Linear Technology, the Linear logo OPTI-LOOP, Burst Mode and PolyPhase n Telecom Systems are registered trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents n DC Power Distribution Systems including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258.
TYPICAL APPLICATION High Efficiency Dual Phase 1.2V/60A Step-Down Converter
VIN INTV 6V TO 14V
Efficiency and Power Loss
CC 22µF 4.7µF V 16V ×4 IN INTVCC PHASMD
vs Load Current
CLKOUT (OPTIONAL) RUN1,2 PGOOD (OPTIONAL) 100 14 THERMAL ILIM IFAST THERMAL 12VIN ENTMPB MODE/PLLIN SENSOR SENSOR 1.8V TG1 TG2 O 95 12 ~400kHz 0.3µH 0.3µH BOOST1 BOOST2 CCM (0.32mΩ DCR) (0.32mΩ DCR) 10 POWER LOSS (W) SW1 LTC3875 SW2 90 EXTVCC 8 BG1 BG2 TAVG 85 PGND TRSET1 6 TRSET2 SNSA1+ EFFICIENCY (%) SNSA2+ 80 SNS1– 4 SNS2– 0.32mΩ SNSD1+ SNSD2+ 75 1.5mΩ TCOMP1 2 TCOMP2 0.32mΩ PLOSS VOUT V + OSNS1 FREQ 20k VOUT 1.5mΩ PLOSS V – OSNS1 V + 1.2V 70 0 + OSNS2 ITH1 0 10 20 30 40 50 60 470µF V – OSNS2 60A 2.5V ×2 TK/SS1 TK/SS2 I 1500pF LOAD CURRENT (A) TH2 + SP 470µF 122k 15k 20k 2.5V ×2 3875 TA01b 0.1µF SP 3875 TA01a 3875fb For more information www.linear.com/LTC3875 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Related Parts