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Numéro de sérieL5987
CategoriePower Management => DC-DC Converters
DescriptionDC-DC Conversion
3 A step-down switching regulator
SociétéST Microelectronics, Inc.
DatasheetTélécharger L5987 datasheet
  • Description courte

  • Features

    A DC output current 18 V input voltage Output voltage adjustable from V 250 kHz switching frequency, programmable to 1 MHz Internal soft-start and inhibit Low dropout operation: 100 % duty cycle Voltage feed-forward Zero load current operation Over current and thermal protection VFQFPN3x3-8L and HSOP8 package


    The is a step down switching regulator with 3.5 A (minimum) current limited embedded power MOSFET, it is able to deliver 3 A current to the load depending on the application conditionals Section 5.7 and Section 5.8). The input voltage can range from 18 V, while the output voltage can be set starting from V to VIN. Having a minimum input voltage 2.9 V, the device is suitable also for 3.3 V bus. Requiring a minimum set of external components, the device includes an internal 250 kHz switching frequency oscillator that can be externally adjusted to 1 MHz. The QFN and the HSOP package with exposed pad allow reducing the RthJA down to 60 °C/W and 40 °C/W respectively.


    Consumer: STB, DVD, DVD recorder, car audio, LCD TV and monitors Industrial: PLD, PLA, FPGA, chargers Networking: XDSL, modems, DC-DC modules Computer: Optical storage, hard disk drive, printers, audio/graphic cards LED driving Application circuit

    This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to change without notice.

    Maximum ratings. 5 Thermal data. 5 Electrical characteristics. 6 Functional description. 8

    Oscillator and synchronization. 9 Soft-start. 11 Error amplifier and compensation. 12 Over-current protection. 13 Inhibit function. 14 Hysteretic thermal shutdown. 14 Maximum DC output current (HSOP8). 15 Maximum DC output current L5987 (VFQFPN). 15

    Input capacitor selection. 17 Inductor selection. 18 Output capacitor selection. 19 Compensation network. 20

    6.4.1 6.4.2 Type III compensation network. 22 Type II compensation network. 26
    Thermal considerations. 30 Layout considerations. 31 Application circuit. 33