Datasheet LTC3728L-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual, 550kHz, 2-Phase Synchronous Regulator |
| Pages / Page | 32 / 1 — FEATURES. DESCRIPTION. Dual, 180° Phased Controllers Reduce Required. … |
| File Format / Size | PDF / 487 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
LTC3728L-1 Dual, 550kHz, 2-Phase Synchronous Regulator
FEATURES DESCRIPTION
n
Dual, 180° Phased Controllers Reduce Required
The LTC®3728L-1 is a dual high performance step-down
Input Capacitance and Power Supply Induced Noise
switching regulator controller that drives all N-channel n
OPTI-LOOP
®
Compensation Minimizes C
synchronous power MOSFET stages. A constant frequency
OUT
n
±1.5% Output Voltage Accuracy
current mode architecture allows phase-lockable frequency n of up to 550kHz. Power loss and noise due to the ESR of
Power Good Output Voltage Indicator
n the input capacitors are minimized by operating the two
Phase-Lockable Fixed Frequency 250kHz to 550kHz
controller output stages out of phase. The LTC3728L-1 n
Over Current Latchoff Disabled
is identical to the LTC3728L except that the LTC3728L-1 n Wide VIN Range: 4.5V to 28V (35V for LTC3728LI-1) lacks the over current latchoff feature. Operation n Very Low Dropout Operation: 99% Duty Cycle OPTI-LOOP compensation allows the transient response to n be optimized over a wide range of output capacitance and Adjustable Soft-Start Current Ramping n ESR values. The precision 0.8V reference and power good Foldback Output Current Limiting output indicator are compatible with future microproces- n Output Overvoltage Protection sor generations, and a wide 4.5V to 28V (30V maximum/ n Low Shutdown IQ: 20μA 35V for LTC3728LI-1) input supply range encompasses n 5V and 3.3V Standby Regulators all battery chemistries. n 3 Selectable Operating Modes: Constant Frequency, A RUN/SS pin for each controller provides soft-start. Burst Mode® Operation and PWM n Current foldback limits MOSFET dissipation during short- 5mm × 5mm QFN and 28-Lead Narrow SSOP circuit conditions. The FCB mode pin can select among Packages Burst Mode operation, constant frequency mode and
APPLICATIONS
continuous inductor current mode or regulate a secondary winding. The LTC3728L-1 includes a power good output n Notebook and Palmtop Computers pin that indicates when both outputs are within 7.5% of n Telecom Systems their designed set point. n Portable Instruments L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Battery-Operated Digital Devices Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. n DC Power Distribution Systems Protected by U.S. Patents including 5929620, 6177787, 6144199, 5471178, 5994885, 6100678.
TYPICAL APPLICATION
VIN + 1μF C 5.2V TO 28V IN 4.7μF 22μF D3 CERAMIC D4 50V M1 VIN PGOOD INTVCC M2 CERAMIC TG1 TG2 L1 L2 3.2μH BOOST1 BOOST2 C 3.2μH B1, 0.1μF CB2, 0.1μF SW1 SW2 LTC3728L-1 BG1 BG2 fIN PLLIN PGND 500kHz SENSE1+ SENSE2+ R R SENSE1 1000pF 1000pF SENSE2 0.01Ω 0.01Ω SENSE1– SENSE2– V V OUT1 OSENSE1 VOSENSE2 VOUT2 R2 5V R4 I 3.3V TH1 ITH2 105k C 5A C1 CC2 63.4k 5A + COUT1 1% RUN/SS1 SGND RUN/SS2 C R1 220pF 220pF R3 1% OUT + 47μF 56μF R R 6V 20k C1 C C C2 20k SS1 SS2 6V 15k 15k SP 1% 0.1μF 0.1μF 1% SP M1, M2: FDS6982S 3728l1 F01
Figure 1. High Effi ciency Dual 5V/3.3V Step-Down Converter
3728l1fc 1
FEATURES DESCRIPTION
n
Dual, 180° Phased Controllers Reduce Required
The LTC®3728L-1 is a dual high performance step-down
Input Capacitance and Power Supply Induced Noise
switching regulator controller that drives all N-channel n
OPTI-LOOP
®
Compensation Minimizes C
synchronous power MOSFET stages. A constant frequency
OUT
n
±1.5% Output Voltage Accuracy
current mode architecture allows phase-lockable frequency n of up to 550kHz. Power loss and noise due to the ESR of
Power Good Output Voltage Indicator
n the input capacitors are minimized by operating the two
Phase-Lockable Fixed Frequency 250kHz to 550kHz
controller output stages out of phase. The LTC3728L-1 n
Over Current Latchoff Disabled
is identical to the LTC3728L except that the LTC3728L-1 n Wide VIN Range: 4.5V to 28V (35V for LTC3728LI-1) lacks the over current latchoff feature. Operation n Very Low Dropout Operation: 99% Duty Cycle OPTI-LOOP compensation allows the transient response to n be optimized over a wide range of output capacitance and Adjustable Soft-Start Current Ramping n ESR values. The precision 0.8V reference and power good Foldback Output Current Limiting output indicator are compatible with future microproces- n Output Overvoltage Protection sor generations, and a wide 4.5V to 28V (30V maximum/ n Low Shutdown IQ: 20μA 35V for LTC3728LI-1) input supply range encompasses n 5V and 3.3V Standby Regulators all battery chemistries. n 3 Selectable Operating Modes: Constant Frequency, A RUN/SS pin for each controller provides soft-start. Burst Mode® Operation and PWM n Current foldback limits MOSFET dissipation during short- 5mm × 5mm QFN and 28-Lead Narrow SSOP circuit conditions. The FCB mode pin can select among Packages Burst Mode operation, constant frequency mode and
APPLICATIONS
continuous inductor current mode or regulate a secondary winding. The LTC3728L-1 includes a power good output n Notebook and Palmtop Computers pin that indicates when both outputs are within 7.5% of n Telecom Systems their designed set point. n Portable Instruments L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Battery-Operated Digital Devices Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. n DC Power Distribution Systems Protected by U.S. Patents including 5929620, 6177787, 6144199, 5471178, 5994885, 6100678.
TYPICAL APPLICATION
VIN + 1μF C 5.2V TO 28V IN 4.7μF 22μF D3 CERAMIC D4 50V M1 VIN PGOOD INTVCC M2 CERAMIC TG1 TG2 L1 L2 3.2μH BOOST1 BOOST2 C 3.2μH B1, 0.1μF CB2, 0.1μF SW1 SW2 LTC3728L-1 BG1 BG2 fIN PLLIN PGND 500kHz SENSE1+ SENSE2+ R R SENSE1 1000pF 1000pF SENSE2 0.01Ω 0.01Ω SENSE1– SENSE2– V V OUT1 OSENSE1 VOSENSE2 VOUT2 R2 5V R4 I 3.3V TH1 ITH2 105k C 5A C1 CC2 63.4k 5A + COUT1 1% RUN/SS1 SGND RUN/SS2 C R1 220pF 220pF R3 1% OUT + 47μF 56μF R R 6V 20k C1 C C C2 20k SS1 SS2 6V 15k 15k SP 1% 0.1μF 0.1μF 1% SP M1, M2: FDS6982S 3728l1 F01
Figure 1. High Effi ciency Dual 5V/3.3V Step-Down Converter
3728l1fc 1
