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ADP1621:  Constant-Frequency, Current-Mode Step-Up DC/DC Controller

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 ...More

ADP1621:  Constant-Frequency, Current-Mode Step-Up DC/DC Controller

Product Description

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.

Applications

  • 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

    • Data Sheet, Rev. A, 12/06

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    • 92% efficiency (no sense resistor required)
    • ±1.0% initial accuracy
    • IC supply voltage range: 2.9 V to 5.5 V
    • Power-input voltage as low as 1.0 V
    • Capable of high supply input voltage (>5.5 V) with an external NPN or a resistor
    • VIN UVLO and 35 mA shunt regulator
    • External slope compensation with 1 resistor
    • Programmable operating frequency (100 kHz to 1.5 MHz) with 1 resistor
    • Lossless current sensing for switch-node voltage <30 V
    • Resistor current sensing for switch-node voltage >30 V
    • Synchronizable to external clock
    • Current-mode operation for excellent line and load transient responses
    • Vin Range: 2.9V-5.5V
    • Vout : n/a
    • Step Up: Yes
    • Shutdown: Y
    • Pkg: MSOP-10

    Functional Block Diagram for ADP1621

    Similar Products

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    Part# Vin Range Pwr Stage Vin Vout Adj Options Multi-Output Shutdown Current Supply Current Switching Frequency Iout (max) Synchronous Step Down Step Up Pkg Product Description Price* (1000-4999)
    ADP1621 2.9V-5.5V As Low As 1V Lossless ISens@<30V Vout, Resistor ISens@>30V No 10µA 3mA 100 KHz - 1.5 MHz - No No Yes MSOP-10 Constant-Frequency, Current-Mode, Step-Up DC/DC Controller $1.32
    ADP1821 3.7V-5.5V 1V-24V 0.6V to 85% PwrStgVin No 10µA 2mA 300 kHz -600 kHz, Sync up to 1 MHz 20A Yes Yes No QSOP-16 20 A Step-Down DC-DC Controller $1.37
    ADP1822 3.7V-5.5V 1V-24V 0.6V to 85% PwrStgVin No 10µA 2mA 300 kHz-600 kHz; Sync up to 1 MHz 20A Yes Yes No QSOP-24 20 A, PWM, Step-Down DC-DC Controller with Margining and Tracking $1.42
    ADP1823 3.7V-20V 1V-24V 0.6V to 85% PwrStgVin Yes 20µA 3mA 300 kHz-600 kHz, Sync up to 1 MHz 20A Yes Yes No LFCSP-32 Versatile Dual, Interleaved Synchronous PWM Buck Controller w/ Tracking $2.13
    ADP1828 3V-20V 1V-24V 0.6V to 85% PwrStgVin No 15µA 3mA 300 kHz to 600 kHz - Yes Yes No QSOP-20 Synchronous Buck PWM, Step-Down, DC-to-DC Controller $1.52
    ADP1829 3V-20V 1V-24V 0.6V to 85% PwrStgVin Yes 20µA 3mA 300 kHz-600 kHz, Sync up to 1 MHz 20A Yes Yes - LFCSP-32 Dual, Interleaved, Step-Down DC-to-DC Controller w/ Tracking $2.13
    ADP1864 3.15V-14V 3.15V-14V 0.8V to Vin No 15µA 350µA 580 kHz 5A No Yes No TSOT-6 5A, Constant Frequency, Current-Mode Step-Down DC/DC Controller in TSOT $1.06
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    *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.
    **Sample availability may be better than production availability. Please enter samples into your cart to check sample availability.