Catalog
Synchronous Step-Down Switching Regulator Controller
| Part | Clock Sync | Supplier Device Package | Operating Temperature [Max] | Operating Temperature [Min] | Number of Outputs | Function | Output Phases | Output Type | Mounting Type | Voltage - Supply (Vcc/Vdd) [Max] | Voltage - Supply (Vcc/Vdd) [Min] | Duty Cycle (Max) [Max] | Frequency - Switching [Min] | Frequency - Switching [Max] | Output Configuration | Control Features | Package / Case | Package / Case | Package / Case | Topology | Synchronous Rectifier | Package / Case |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Analog Devices | 16-SSOP | 85 °C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 250 kHz | 750 kHz | Positive | Current Limit Enable Frequency Control Soft Start Tracking | 0.154 in | 16-SSOP | 3.9 mm | Buck | |||
Analog Devices | 16-QFN (3x3) | 125 ¯C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 235 kHz | 750 kHz | Positive | Current Limit Enable Frequency Control Soft Start Tracking | 16-WFQFN Exposed Pad | Buck | |||||
Analog Devices | 16-MSOP-EP | 150 °C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 235 kHz | 750 kHz | Positive | Enable Frequency Control Power Good Soft Start Tracking | 16-TFSOP Exposed Pad | Buck | 0.118 in 3 mm | ||||
Analog Devices | 16-QFN (3x3) | 125 ¯C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 235 kHz | 750 kHz | Positive | Enable Frequency Control Power Good Soft Start Tracking | 16-WFQFN Exposed Pad | Buck | |||||
Analog Devices | 16-MSOP-EP | 85 °C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 250 kHz | 750 kHz | Positive | Current Limit Enable Frequency Control Soft Start Tracking | 16-TFSOP Exposed Pad | Buck | 0.118 in 3 mm | ||||
Analog Devices | 16-QFN (3x3) | 125 ¯C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 235 kHz | 750 kHz | Positive | Current Limit Enable Frequency Control Soft Start Tracking | 16-WFQFN Exposed Pad | Buck | |||||
Analog Devices | 16-MSOP-EP | 150 °C | -55 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 235 kHz | 750 kHz | Positive | Enable Frequency Control Power Good Soft Start Tracking | 16-TFSOP Exposed Pad | Buck | 0.118 in 3 mm | ||||
Analog Devices | 16-MSOP-EP | 125 ¯C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 235 kHz | 750 kHz | Positive | Enable Frequency Control Power Good Soft Start Tracking | 16-TFSOP Exposed Pad | Buck | 0.118 in 3 mm | ||||
Analog Devices | 16-MSOP-EP | 85 °C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 250 kHz | 750 kHz | Positive | Enable Frequency Control Power Good Soft Start Tracking | 16-TFSOP Exposed Pad | Buck | 0.118 in 3 mm | ||||
Analog Devices | 16-MSOP-EP | 125 ¯C | -40 °C | 1 | Step-Down | 1 | Transistor Driver | Surface Mount | 38 V | 4 V | 99 % | 250 kHz | 750 kHz | Positive | Enable Frequency Control Power Good Soft Start Tracking | 16-TFSOP Exposed Pad | Buck | 0.118 in 3 mm |
Key Features
• Wide VINRange: 4V to 38V Operation
• RSENSEor DCR Current Sensing
• ±1% Output Voltage Accuracy
• Phase-Lockable Fixed Frequency: 250kHz to 750kHz
• Dual N-Channel MOSFET Synchronous Drive
• Very Low Dropout Operation: 99% Duty Cycle
• Adjustable Output Voltage Soft-Start or Tracking
• Output Current Foldback Limiting
• Output Overvoltage Protection
• 5V Internal Regulator
• OPTI-LOOP®Compensation Minimizes COUT
• Selectable Continuous, Pulse-Skipping or Burst Mode®Operation at Light Loads
• Low Shutdown IQ: 20μA
• VOUTRange: 0.8V to 5.5V
• Thermally Enhanced 16-Lead MSOP, 16-Lead Narrow SSOP or 3mm × 3mm QFN Package
• AEC-Q100 Qualified for Automotive Applications
Description
AI
The LTC3851A-1 is a high performance synchronous step-down switching regulator controller that drives an all N-channel synchronous power MOSFET stage. A constant frequency current mode architecture allows a phase-lockable frequency of up to 750kHz.OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3851A-1 features a precision 0.8V reference and a power good indicator. A wide 4V to 38V (40V absolute maximum) input supply range encompasses most battery configurations and intermediate bus voltages.The TK/SS pin ramps the output voltage during start-up and shutdown with coincident or ratiometric tracking. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode operation, pulse-skipping mode or continuous inductor current mode at light loads and allows the IC to be synchronized to an external clock. The LTC3851A-1 contains an improved PLL compared to the LTC3851-1.The LTC3851A-1 is identical to the LTC3851A except that the ILIMpin is replaced by PGOOD.FeaturesLTC3851Not Recommended For New DesignsLTC3851-1Not Recommended For New DesignsLTC3851AAdjustable Current LimitLTC3851A-1PGOOD OutputApplicationsAutomotive SystemsTelecom SystemsIndustrial EquipmentDistributed DC Power Systems