Analog Devices LT8711 | Demoboard DC2234

Description

Demonstration circuit 2234A is a synchronous sepic converter featuring the LT®8711 multitopology switching controller. The LT8711 is a current mode PWM DC/DC controller with a dual input LDO to optimize gate driver efficiency. Ultralow 15μA quiescent current in low noise Burst Mode® operation achieves high efficiency at very light loads and helps extend the run-time in battery powered applications when in standby mode. The LT8711 switching frequency can be programmed either via oscillator resistor or external clock over a 100kHz to 750kHz range.The demo board regulates a 12V, 4A output from a 4.5V to 40V input source, and operates at 200kHz switching frequency. The rated maximum load current is 4A, while derating is necessary for certain input voltage and thermal conditions.The SYNC pin on the demo board is grounded (JP1 at BURST position) by default for low ripple high efficiency Burst Mode operation at light load. To synchronize to an external clock, move JP1 to SYNC and apply the external clock to the SYNC turret. Force continuous conduction mode can be selected by moving JP1 shunt to FCM position.The DC2234A can be modified from a SEPIC converter to other topologies. Synchronous BOOST and some other schematics are provided in the data sheet. Please consult the factory or LT8711 data sheet for details regarding how to customize the DC2234A or how to design different topologies for custom specifications.The LT8711 includes many other features such as user configurable under voltage lockout, soft-start, input voltage feedforward regulation, and it is easily configured as synchronous buck, boost, SEPIC or nonsynchronous buck-boost converter. The data sheet gives a complete description of the device, operation and application information. The data sheetmust be read in conjunction with this demo manual for DC2234A. The LT8711 is assembled in a 20-lead plastic TSSOP package with a thermally enhanced ground pad. Proper board layout is essential for maximum thermal performance. See the Layout Considerations section in the data sheet.

Features

• Easily Configurable as a Synchronous Buck, Boost, SEPIC, ZETA or Nonsynchronous Buck-Boost Converter
• Wide Input Range: 4.5V to 42V (VIN Can Operate to 0V, when EXTVCC > 4.5V)
• Automatic Low Noise Burst Mode® Operationnn Low IQ in Burst Mode Operation (15μA Operating)
• Input Voltage Regulation for High Impedance Source
• 100% Duty Cycle in Dropout (Buck Mode)
• 2A Gate Drivers (BG and TG)
• Adjustable Soft-Start with One Capacitor
• Frequency Programmable from 100kHz to 750kHz
• Can Be Synchronized to External Clock
• Available in 20-Lead TSSOP and 20-Lead 3mm×4mm QFN Packages

Typical applications

• Automotive Systems
• Industrial Supplies
• General Purpose DC/DC Conversion
• Solar Panel Power Converter

More information

• Datasheet
• IC product information