Datasheet LTC3850, LTC3850-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual, 2-Phase Synchronous Step-Down Switching Controller |
| Pages / Page | 38 / 1 — FEATURES. DESCRIPTION. Dual, 180° Phased Controllers Reduce Required. … |
| Revision | D |
| File Format / Size | PDF / 1.2 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Dual, 180° Phased Controllers Reduce Required. Input Capacitance and Power Supply Induced Noise
Model Line for this Datasheet
- LTC3850EGN#PBF LTC3850EGN#TRPBF LTC3850EGN#WPBF LTC3850EGN#WTRPBF LTC3850EGN-1#PBF LTC3850EGN-1#TRPBF LTC3850EGN-1#WPBF LTC3850EGN-1#WTRPBF LTC3850EUF#PBF LTC3850EUF#TRPBF LTC3850EUFD#PBF LTC3850EUFD#TRPBF LTC3850IGN#PBF LTC3850IGN#TRPBF LTC3850IGN#WPBF LTC3850IGN#WTRPBF LTC3850IGN-1#PBF LTC3850IGN-1#TRPBF LTC3850IGN-1#WPBF LTC3850IGN-1#WTRPBF LTC3850IUF#PBF LTC3850IUF#TRPBF LTC3850IUFD#PBF LTC3850IUFD#TRPBF
Text Version of Document
LTC3850/LTC3850-1 Dual, 2-Phase Synchronous Step-Down Switching Controller
FEATURES DESCRIPTION
n
Dual, 180° Phased Controllers Reduce Required
The LTC®3850 is a high performance dual synchronous
Input Capacitance and Power Supply Induced Noise
step-down switching regulator controller that drives all n
High Efficiency: Up to 95%
N-channel power MOSFET stages. A constant-frequency n
RSENSE or DCR Current Sensing
current mode architecture allows a phase-lockable fre- n
±1% 0.8V Output Voltage Accuracy
quency of up to 780kHz. Power loss and supply noise are n
Phase-Lockable Fixed Frequency 250kHz to 780kHz
minimized by operating the two controller output stages n Supports Pre-Biased Output out of phase. n Dual N-Channel MOSFET Synchronous Drive OPTI-LOOP® compensation allows the transient response n Wide VIN Range: 4V to 24V (30V for LTC3850I) to be optimized over a wide range of output capacitance Operation and ESR values. The LTC3850 features a precision 0.8V n Adjustable Soft-Start Current Ramping or Tracking reference and a power good output indicator. A wide 4V n Foldback Output Current Limiting to 24V (28V maximum/30V for LTC3850I) input supply n Power Good Output Voltage Monitor range encompasses most battery chemistries and inter- n 28-Pin 4mm × 4mm, 4mm × 5mm QFN and Narrow mediate bus voltages. SSOP Packages n AEC-Q100 Qualified for Automotive Applications Independent TK/SS pins for each controller ramp the
APPLICATIONS
output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. n The MODE/PLLIN pin selects among Burst Mode® opera- Notebook and Palmtop Computers n tion, pulse-skipping mode, or continuous inductor cur- Portable Instruments n rent mode and allows the IC to be synchronized to an Battery-Operated Digital Devices n external clock. DC Power Distribution Systems All registered trademarks and trademarks are the property of their respective owners. Protected The LTC3850 is available in low profile 28-pin 4mm × by U.S. patents, including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258. 4mm, 4mm × 5mm QFN and narrow SSOP packages.
TYPICAL APPLICATION High Efficiency Dual 3.3V/2.5V Step-Down Converter Efficiency
VIN 7V TO 100 10000 22µF 4.7µF 24V VIN = 12V 50V 95 VOUT = 3.3V EFFICIENCY VIN PGOOD INTVCC TG1 TG2 90 0.1µF 0.1µF POWER LOSS (mW) 85 1000 2.2µH BOOST1 BOOST2 2.2µH 80 SW1 SW2 LTC3850 75 BG1 BG2 2.2k 2.2k 70 500kHz MODE/PLLIN PGND EFFICIENCY (%) 100 65 ILIM FREQ/PLLFLTR POWER LOSS 60 SENSE1+ SENSE2+ 0.1µF RUN1 RUN2 0.1µF 55 VOUT1 SENSE1– SENSE2– VOUT2 3.3V 50 10 VFB1 VFB2 2.5V 10 100 1000 10000 5A 63.4k 43.2k 5A ITH1 ITH2 LOAD CURRENT (mA) 220pF 10nF 220pF TK/SS1 SGND TK/SS2 38501 TA01b 100µF 20k 100µF 20k 6V 15k 10k 15k 0.1µF 0.1µF 6V 38501 TA01 Rev. D Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
FEATURES DESCRIPTION
n
Dual, 180° Phased Controllers Reduce Required
The LTC®3850 is a high performance dual synchronous
Input Capacitance and Power Supply Induced Noise
step-down switching regulator controller that drives all n
High Efficiency: Up to 95%
N-channel power MOSFET stages. A constant-frequency n
RSENSE or DCR Current Sensing
current mode architecture allows a phase-lockable fre- n
±1% 0.8V Output Voltage Accuracy
quency of up to 780kHz. Power loss and supply noise are n
Phase-Lockable Fixed Frequency 250kHz to 780kHz
minimized by operating the two controller output stages n Supports Pre-Biased Output out of phase. n Dual N-Channel MOSFET Synchronous Drive OPTI-LOOP® compensation allows the transient response n Wide VIN Range: 4V to 24V (30V for LTC3850I) to be optimized over a wide range of output capacitance Operation and ESR values. The LTC3850 features a precision 0.8V n Adjustable Soft-Start Current Ramping or Tracking reference and a power good output indicator. A wide 4V n Foldback Output Current Limiting to 24V (28V maximum/30V for LTC3850I) input supply n Power Good Output Voltage Monitor range encompasses most battery chemistries and inter- n 28-Pin 4mm × 4mm, 4mm × 5mm QFN and Narrow mediate bus voltages. SSOP Packages n AEC-Q100 Qualified for Automotive Applications Independent TK/SS pins for each controller ramp the
APPLICATIONS
output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. n The MODE/PLLIN pin selects among Burst Mode® opera- Notebook and Palmtop Computers n tion, pulse-skipping mode, or continuous inductor cur- Portable Instruments n rent mode and allows the IC to be synchronized to an Battery-Operated Digital Devices n external clock. DC Power Distribution Systems All registered trademarks and trademarks are the property of their respective owners. Protected The LTC3850 is available in low profile 28-pin 4mm × by U.S. patents, including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258. 4mm, 4mm × 5mm QFN and narrow SSOP packages.
TYPICAL APPLICATION High Efficiency Dual 3.3V/2.5V Step-Down Converter Efficiency
VIN 7V TO 100 10000 22µF 4.7µF 24V VIN = 12V 50V 95 VOUT = 3.3V EFFICIENCY VIN PGOOD INTVCC TG1 TG2 90 0.1µF 0.1µF POWER LOSS (mW) 85 1000 2.2µH BOOST1 BOOST2 2.2µH 80 SW1 SW2 LTC3850 75 BG1 BG2 2.2k 2.2k 70 500kHz MODE/PLLIN PGND EFFICIENCY (%) 100 65 ILIM FREQ/PLLFLTR POWER LOSS 60 SENSE1+ SENSE2+ 0.1µF RUN1 RUN2 0.1µF 55 VOUT1 SENSE1– SENSE2– VOUT2 3.3V 50 10 VFB1 VFB2 2.5V 10 100 1000 10000 5A 63.4k 43.2k 5A ITH1 ITH2 LOAD CURRENT (mA) 220pF 10nF 220pF TK/SS1 SGND TK/SS2 38501 TA01b 100µF 20k 100µF 20k 6V 15k 10k 15k 0.1µF 0.1µF 6V 38501 TA01 Rev. D Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
