Datasheet LTC3850-2 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual, 2-Phase Synchronous Step-Down Switching Controller |
| Pages / Page | 36 / 1 — FEATURES. DESCRIPTION. Dual, 180. Phased Controllers Reduce Required. … |
| File Format / Size | PDF / 417 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Dual, 180. Phased Controllers Reduce Required. Input Capacitance and Power Supply Induced Noise
Model Line for this Datasheet
Text Version of Document
LTC3850-2 Dual, 2-Phase Synchronous Step-Down Switching Controller
FEATURES DESCRIPTION
n
Dual, 180
°
Phased Controllers Reduce Required
The LTC®3850-2 is a high performance dual synchronous
Input Capacitance and Power Supply Induced Noise
step-down switching regulator controller that drives all n
High Effi ciency: Up to 95%
N-channel power MOSFET stages. A constant-frequency n
RSENSE or DCR Current Sensing
current mode architecture allows a phase-lockable n ±
1% 0.8V Output Voltage Accuracy
frequency of up to 780kHz. Power loss and supply noise n
Phase-Lockable Fixed Frequency 250kHz to 780kHz
are minimized by operating the two controller output n Supports Pre-Biased Output stages out of phase. n Dual N-Channel MOSFET Synchronous Drive OPTI-LOOP® compensation allows the transient response n Wide VIN Range: 4V to 30V Operation to be optimized over a wide range of output capacitance n Adjustable Soft-Start Current Ramping or Tracking and ESR values. The LTC3850-2 features a precision 0.8V n Foldback Output Current Limiting reference and a power good output indicator. A wide 4V n Output Overvoltage Protection to 30V input supply range encompasses most battery n Power Good Output Voltage Monitor chemistries and intermediate bus voltages. n 28-Pin Narrow SSOP Package Independent TK/SS pins for each controller ramp the
APPLICATIONS
output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit condi- n Notebook and Palmtop Computers tions. The MODE/PLLIN pin selects among Burst Mode® n Portable Instruments operation, pulse-skipping mode, or continuous inductor n Battery-Operated Digital Devices current mode and allows the IC to be synchronized to an n DC Power Distribution Systems external clock. L, LT, LTC, LTM, OPTI-LOOP and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. The LTC3850-2 is identical to the LTC3850-1, except they Patents, including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258. have different pin assignments.
TYPICAL APPLICATION High Effi ciency Dual 3.3V/2.5V Step-Down Converter Effi ciency
VIN 7V TO 100 10000 22μF V 4.7μF 26V IN = 12V 50V 95 VOUT = 3.3V EFFICIENCY VIN PGOOD INTVCC 90 TG1 TG2 0.1μF 0.1μF POWER LOSS (mW) 85 1000 2.2μH BOOST1 BOOST2 2.2μH 80 SW1 SW2 LTC3850-2 75 2.2k BG1 BG2 70 2.2k 500kHz MODE/PLLIN PGND EFFICIENCY (%) 100 65 EXT FREQ/PLLFLTR VCC POWER LOSS 60 SENSE1+ SENSE2+ 0.1μF RUN1 RUN2 0.1μF 55 VOUT1 SENSE1– SENSE2– VOUT2 50 10 3.3V V 2.5V FB1 VFB2 10 100 1000 10000 5A 63.4k 43.2k 5A ITH1 ITH2 LOAD CURRENT (mA) 220pF 10nF 220pF TK/SS1 SGND TK/SS2 38502 TA01b 100μF 20k 100μF 15k 20k 6V 10k 15k 0.1μF 0.1μF 6V 38502 TA01 38502f 1
FEATURES DESCRIPTION
n
Dual, 180
°
Phased Controllers Reduce Required
The LTC®3850-2 is a high performance dual synchronous
Input Capacitance and Power Supply Induced Noise
step-down switching regulator controller that drives all n
High Effi ciency: Up to 95%
N-channel power MOSFET stages. A constant-frequency n
RSENSE or DCR Current Sensing
current mode architecture allows a phase-lockable n ±
1% 0.8V Output Voltage Accuracy
frequency of up to 780kHz. Power loss and supply noise n
Phase-Lockable Fixed Frequency 250kHz to 780kHz
are minimized by operating the two controller output n Supports Pre-Biased Output stages out of phase. n Dual N-Channel MOSFET Synchronous Drive OPTI-LOOP® compensation allows the transient response n Wide VIN Range: 4V to 30V Operation to be optimized over a wide range of output capacitance n Adjustable Soft-Start Current Ramping or Tracking and ESR values. The LTC3850-2 features a precision 0.8V n Foldback Output Current Limiting reference and a power good output indicator. A wide 4V n Output Overvoltage Protection to 30V input supply range encompasses most battery n Power Good Output Voltage Monitor chemistries and intermediate bus voltages. n 28-Pin Narrow SSOP Package Independent TK/SS pins for each controller ramp the
APPLICATIONS
output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit condi- n Notebook and Palmtop Computers tions. The MODE/PLLIN pin selects among Burst Mode® n Portable Instruments operation, pulse-skipping mode, or continuous inductor n Battery-Operated Digital Devices current mode and allows the IC to be synchronized to an n DC Power Distribution Systems external clock. L, LT, LTC, LTM, OPTI-LOOP and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. The LTC3850-2 is identical to the LTC3850-1, except they Patents, including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258. have different pin assignments.
TYPICAL APPLICATION High Effi ciency Dual 3.3V/2.5V Step-Down Converter Effi ciency
VIN 7V TO 100 10000 22μF V 4.7μF 26V IN = 12V 50V 95 VOUT = 3.3V EFFICIENCY VIN PGOOD INTVCC 90 TG1 TG2 0.1μF 0.1μF POWER LOSS (mW) 85 1000 2.2μH BOOST1 BOOST2 2.2μH 80 SW1 SW2 LTC3850-2 75 2.2k BG1 BG2 70 2.2k 500kHz MODE/PLLIN PGND EFFICIENCY (%) 100 65 EXT FREQ/PLLFLTR VCC POWER LOSS 60 SENSE1+ SENSE2+ 0.1μF RUN1 RUN2 0.1μF 55 VOUT1 SENSE1– SENSE2– VOUT2 50 10 3.3V V 2.5V FB1 VFB2 10 100 1000 10000 5A 63.4k 43.2k 5A ITH1 ITH2 LOAD CURRENT (mA) 220pF 10nF 220pF TK/SS1 SGND TK/SS2 38502 TA01b 100μF 20k 100μF 15k 20k 6V 10k 15k 0.1μF 0.1μF 6V 38502 TA01 38502f 1
