Constant-Frequency, Current-Mode Step-Up DC/DC Controller

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Product Details

The ADP1621 is a fixed-frequency, pulse-width modulation (PWM), current-mode, step-up converter controller. It drives an external n-channel MOSFET to convert the input voltage to a higher output voltage. The ADP1621 can also be used to drive flyback, SEPIC, and forward converter topologies, either isolated or nonisolated.

The ADP1621 eliminates the use of a current-sense power resistor by measuring the voltage drop across the on resistance of the n-channel MOSFET. This technique, allowed up to a maximum voltage of 30 V at the switch node, maximizes efficiency and reduces cost. For switch-node voltages higher than 30 V or for more accurate current limiting, the CS pin can be connected to a current-sense resistor in the source of the MOSFET. The slope compensation is implemented by an external resistor, allowing a wide range of external components (inductors and MOSFETs), and can be chosen for various switching frequencies and input and output voltages.

The ADP1621 supply input voltage range is 2.9 V to 5.5 V, although higher input voltages are possible with the use of a small-signal NPN pass transistor or a single resistor. The voltage of the power input can be as low as 1 V for fuel cell applications. The switching frequency is set by an external resistor over a range of 100 kHz to 1.5 MHz and can be synchronized to an external clock by using the SDSN pin. The shutdown quiescent current is less than 10 μA. The ADP1621 has a thermal shutdown feature that shuts down the gate driver when the junction temperature reaches approximately 150°C. The internal soft start circuit limits inrush current at startup. The ADP1621 is available in the 10-lead MSOP lead-free package and is specified over the −40°C to +125°C junction temperature range.


  • APD bias
  • Portable electronic equipment
  • Isolated dc/dc converter
  • Step-up/step-down dc/dc converter
  • LED driver for laptop computer and navigation system
  • LCD backlighting

Product Lifecycle

checked Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits


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Product Details

The input range for the demo board is 3.0 V to 3.6 V, and the output voltage is 5 V with a maximum load of 2 A. The design is done in a bootstrapped configuration as shown in Figure 13. The switching frequency fSW is set to 600 kHz with a 36 kΩ resistor. This design is done in all multilayer ceramic capacitors (MLCC), although other types of capacitors can be used, such as the aluminum polymer or aluminum electrolytic capacitors. The PCB is laid out in such a way that the user can easily modify the demo board for other input and output configurations.




Product Details

The Isolated Inverter Platform is a rapid development system for hardware and/or software development in three-phase inverter applications, with a particular focus on motor control. Flexible evaluation of ADI isolation technology in a highly configurable system-oriented platform is enabled with multiple test-points, and connectivity options. An easy-plug connector allows controller connection to an ADSP-CM408 processor evaluation board, while additional 0.1” headers enable alternative connectivity to other processor or FPGA platforms. The benefits of ADI isolated sigma-delta converters for voltage and current measurement, isolated gate drivers, and power controllers can be explored in a full system application at dc bus levels up to 800V. There are 2 models available, isolated inverter platform, and isolated inverter platform with full featured IGBT drivers.

Solution Overview
The isolated inverter platform and isolated inverter platform with full featured IGBT drivers offer a power board that runs from a dc input and provides a three-phase variable frequency, variable voltage, and variable dead-time PWM output to a three-phase motor or load. The inverter is provided as an open loop platform, but feedback signals are provided to enable the application developer to close the control loop. For the isolated inverter platform (EV-MCS-ISOINV-Z), two isolated current,phase to phase and dc bus voltage feedback signals are provided to the control side of the board via sigma-delta modulators, and these can be used for development of control algorithms. The inverter is made up of a three-phase six-IGBT bridge, with the IGBTs rated at 1200V and driven by three dual isolated gate drivers (ADuM4223). For the isolated inverter platform with full featured IGBT drivers (EV-MCS-ISOINVEP-Z), three isolated phase current and dc bus voltage feedback signals are provided to the control side of the board via sigma-delta modulators, and these can be used for development of control algorithms. The inverter is made up of a three-phase six-IGBT bridge, with the IGBTs rated at 1200V and driven by six individual isolated gate drivers (ADuM4135) with desaturation protection and Miller clamp. For both platforms, a DC – rather than AC- input is provided to allow flexibility on the dc bus voltage level (rather than it being limited to the ac line peak).

The board is designed to work from a DC supply in the range 24Vdc-800Vdc.. The power board is rated up to 2kVA without forced air cooling. Additional power throughput can be achieved with fan cooling added. A series connected diode implements a half-wave rectifier at the input, so if needed, the power board can be driven from an AC supply. However output power is limited in this case. If a full AC front-end is required, the inverter platform can be utilized in conjunction with the ADP1047 evaluation board up to 300W, or the ADP1048 evaluation board up to 600W. An isolated I2C interface is provided on the inverter board so that the ADP104x evaluation board can be easily controlled by the same processor/FPGA interface. The inverter kit has the hardware and software required to spin a three-phase motor under open loop speed control in conjunction with an ADSP-CM408 EZ Kit. The demo software is provided as an IAR Embedded Workbench C project or an executable file which can be flashed to the ADSP-CM408 processor using the ADI serial boot-loader utility. A .NET-based graphical user interface (GUI) is provided to enable motor start-stop, open loop Volts/Hertz speed control, and data visualization.

Kit Contents

  • Isolated Inverter Board, 24-800Vdc, 2Kva (2 Versions)
  • Adapter board for connection to EZkit
  • USB to serial adapter for using GUI


  • IAR Embedded Workbench C project
  • Executable Demo Application
  • .NET-based Graphical User Interface (GUI)



EVAL-FMCMOTCON2 Circuit Diagram

Product Details

The AD-FMCMOTCON2-EBZ is a complete high performance servo system on an FPGA Mezzanine Card (FMC) board, the purpose of which is to provide a complete motor drive system demonstrating efficient and high dynamic control of three phase PMSM and induction motors up to 48V and 20A.

Two motors can be driven at the same time, each motor having its separate power supply. The system incorporates high quality power sources; reliable power, control, and feedback signals isolation; accurate measurement of motor current & voltage signals; high speed interfaces for control signals to allow fast controller response; industrial Ethernet high speed interfaces; single ended Hall, differential Hall, encoder and resolver interfaces; digital position sensors interface; flexible control with a FPGA/SoC interface.

The kit consists of two boards: a controller board and a drive board. An optional AD-DYNO2-EBZ dynamometer can also be purchased through Avnet and is intended to be an extension of the drive system.

Controller Board

  • Digital board for interfacing with the low and high voltage drive boards
  • Compatible with all Xilinx FPGA platforms with FMC LPC or HPC connectors
  • FMC signals voltage adaptation interface for seamless operation on all FMC voltage levels
  • Fully isolated digital control and feedback signals
  • Isolated Xilinx XADC interface
  • 2 x Gbit Ethernet PHYs for high speed industrial communication, with 3rd party EtherCAT support
  • Single ended Hall, Differential Hall, Encoder, Resolver interfaces
  • Digital sensors interfaces
    • EnDat
    • BISS Interface

Drive Board

  • Drives motors up to 48V @ 20A
  • Drives 2 motors simultaneously
  • High frequency drive stage implemented with ADI isolated gate drivers
  • Supported motor types
    Brushed DC
    Stepper (bipolar / unipolar)
  • Integrated over current protection
  • Reverse voltage protection
  • Current and Voltage measurement using isolated ADCs
  • BEMF zero cross detection for sensorless control of PMSM or BLDC motors
  • Separate voltage supplies for the 2 motors so that the motors don't influence each other

Dynamometer System with Embedded Control

  • Two BLDC motors connected by a rigid couple in a dyno setup, which can be used to test real-time motor control performance.
  • One BLDC motor acts as an electronically adjustable load and is driven by the embedded control system. This motor can be directly connected to the FMC motor drive to get complex / active loads. The load can be driven also by the AD-FMCMOTCON2-EBZ to implement dynamic load profiles.
  • The other BLDC motor is driven by the FMC motor drive.
  • Measurement and display of load motor current
  • Measurement and display of load motor speed
  • External control using Analog Discovery and MathWorks Instrumentation Control Toolbox


Example reference designs showing how to use the platform with Xilinx® FPGAs or SoCs and high performance control algorithms from Mathworks® are provided together with the hardware. Information on the FMC board, and how to use it, the design package that surrounds it, and the software which can make it work, can be found by clicking the software link.

Tools & Simulations

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Design Tools

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Reference Designs


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CN0342 Circuit Diagram

CN0342 Photo


CN0328 Circuit Diagram

CN0328 Photo

Reference Materials

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Design Resources

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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.

ADP1621 Material Declaration
PCN-PDN Information Quality And Reliability Symbols and Footprints



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Evaluation Boards Pricing displayed is based on 1-piece.
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.