New Content (1)
Features and Benefits
- Dual Buck Plus Single Boost Synchronous 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 and Boost Output Voltages up to 40V
- Pass-Thru™ Operation: 100% Duty Cycle for Boost Synchronous MOSFET
- RSENSE or DCR Current Sensing
- 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
- Very Low Buck Dropout Operation: 99% Duty Cycle
- Low Shutdown IQ: 1.5μA
- Small 38-Lead 5mm × 7mm QFN Package
- AEC-Q100 Automotive Qualification in Process
The LTC7817 is a high performance triple output (buck/buck/boost) synchronous 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 LTC7817 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 LTC7817 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 LTC7817 features a precision 0.8V reference for the bucks, 1.2V reference for the boost and a power good output indicator.
The LTC7817 synchronous boost Pass-Thru capability minimizes losses in automotive start-stop applications.
- 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 3033A is a triple output synchronous step-up/dual step-down supply featuring the LTC7817. The demonstration circuit is designed for two buck outputs 5V/10A, 3.3V/10A supplied by a boosted 10V output. Benefiting from this feature, the buck outputs are able to 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-inch by 1½-inch, while the main boost circuit area is ¾-inch by 1¾-inch. The package style for the LTC7817 is a 38-pin exposed pad QFN.
The main features of the board include rail tracking (buck channels only), an internal 5V linear regulator for bias, separated RUN pins for each output, a PGOOD signal (CH1 only), and a mode selector that allow the converter to run in forced continuous mode (FCM), pulse-skipping (PSM) or Burst Mode® operation (BURST). Synchronization to an external clock is also possible. The LTC7817 data sheet gives a complete description of these parts, operation and application information. The data sheet must be read in conjunction with this quick start guide for demo circuit 3033A.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
Models for the following parts are available in LTspice:
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.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.