Features and Benefits
- Dual Synchronous Buck Plus Single Boost Controllers
- Low Operating IQ:
- 14μA (14V to 3.3V, Channel 1 On)
- Outputs Remain in Regulation Through Cold Crank Down to 1V Input Supply Voltage
- Wide Bias Input Voltage Range: 4.5V to 40V
- Buck Output Voltages Up to 40V
- Boost Output Voltage Limited Only by External Components
- Spread Spectrum Operation
- RSENSE or DCR Current Sensing
- Low Battery Indicator for Automotive Applications
- Programmable Fixed Frequency (100kHz to 3MHz)
- Phase-Lockable Frequency (100kHz to 3MHz)
- Selectable Continuous, Pulse-Skipping, or Low Ripple Burst Mode® Operation at Light Loads
- Boost Channel Current Monitor Output
- Low Shutdown IQ: 1.5μA
- Small 40-Lead 6mm × 6mm QFN Package
- AEC-Q100 Qualified for Automotive Applications
The LTC7811 is a high performance triple output (buck/buck/boost) DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Its constant frequency current mode architecture allows a phase-lockable switching frequency of up to 3MHz. The LTC7811 operates from a wide 4.5V to 40V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC7811 can operate from an input supply as low as 1V after start-up.
The very low no-load quiescent current extends operating run time in battery powered systems. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC7811 features a precision 0.8V reference for the bucks, 1.2V reference for the boost and a power good output indicator.
The LTC7811 additionally features spread spectrum operation which significantly reduces the peak radiated and conducted noise on both the input and output supplies, making it easier to comply with electromagnetic interference (EMI) standards.
- Automotive and Transportation
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
Demonstration circuit DC3151A is a non-synchronous boost plus dual synchronous buck power supply featuring the LTC7811. The demonstration circuit is designed for two buck outputs 5V/10A, 3.3V/7A supplied by a boosted 9.5V output. Benefiting from this feature, the buck outputs can maintain regulation over a wide input voltage range of 4.5V to 36V which is suitable for automotive or other battery fed applications. Also, the demonstration circuit uses a drop-in layout whereas the main buck circuit components fit in an area of ¾" by 1½", while the main boost circuit area is ¾" by 1¾". The package style for the LTC7811 is a 40-pin exposed pad QFN.
The main features of the board include rail tracking (Buck channels only), an internal 5V linear regulator for bias, separate RUN pins for each output, a PGOOD signal (CH1 only), battery monitor and a Mode selector that allow the converter to run in CCM, Pulse-skipping or Burst Mode operation. Spread Spectrum Mode is available for EMI improvement. Synchronization to an external clock is also possible.
The LTC7811 datasheet gives a complete description of this part, its operation and application information. The datasheet must be read in conjunction with the quick start guide for demo circuit 3151.
Documentation & Resources
DC3151A - Demo Manual (Rev. 0)7/19/2021
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.
|Part Number||Material Declaration||Reliability Data||Pin/Package Drawing||CAD Symbols, Footprints & 3D Models|
|LTC7811IUJ#PBF||Material Declaration||Reliability Data||40-Lead QFN (6mm x 6mm x 0.75mm w/ EP)|
|LTC7811IUJ#TRPBF||Material Declaration||Reliability Data||40-Lead QFN (6mm x 6mm x 0.75mm w/ EP)|
|LTC7811IUJ#WPBF||Material Declaration||Reliability Data||40-Lead QFN (6mm x 6mm x 0.75mm w/ EP)|
|LTC7811IUJ#WTRPBF||Material Declaration||Reliability Data||40-Lead QFN (6mm x 6mm x 0.75mm w/ EP)|
|LTC7811JUJ#WPBF||Material Declaration||Reliability Data||40-Lead QFN (6mm x 6mm x 0.75mm w/ EP)|
|LTC7811JUJ#WTRPBF||Material Declaration||Reliability Data||40-Lead QFN (6mm x 6mm x 0.75mm w/ EP)|
|Wafer Fabrication Data|
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.