L5981 1 A step-down switching regulator Datasheet - production data Industrial: chargers, PLD, PLA, FPGA Networking: XDSL, modems, DC-DC modules Computer: optical storage, hard disk drive, printers, audio/graphic cards VFQFPN8 3 mm x 3 mm LED driving Description Features The L5981 is a step-down switching regulator 1 A DC output current with a 1.5 A (min.) current limited embedded 2.9 V to 18 V input voltage Power MOSFET, so it is able to deliver in excess Output voltage adjustable from 0.6 V of 1 A DC current to the load depending on the application condition. 250 kHz switching frequency, programmable up to 1 MHz The input voltage can range from 2.9 V to 18 V, while the output voltage can be set starting from Internal soft-start and inhibit 0.6 V to V . Having a minimum input voltage of IN Low dropout operation: 100% duty cycle 2.9 V, the device is suitable also for a 3.3 V bus. Voltage feedforward Requiring a minimum set of external components, Zero load current operation the device includes an internal 250 kHz switching Overcurrent and thermal protection frequency oscillator that can be externally adjusted up to 1 MHz. VFQFPN8 3 mm x 3 mm package The VFQFPN8 package with an exposed pad allows reducing the R down to approximately Applications thJA 60 C/W. Consumer: STB, DVD, DVD recorder, car audio, LCD TV and monitors Figure 1. Application circuit May 2014 DocID13004 Rev 7 1/37 This is information on a product in full production. www.st.comContents L5981 Contents 1 Pin settings 4 1.1 Pin connection 4 1.2 Pin description 4 2 Maximum ratings 5 2.1 Absolute maximum ratings . 5 2.2 Thermal data . 5 3 Electrical characteristics . 6 4 Functional description . 8 4.1 Oscillator and synchronization 9 4.2 Soft-start .11 4.3 Error amplifier and compensation 12 4.4 Overcurrent protection . 13 4.5 Inhibit function . 14 4.6 Hysteretic thermal shutdown 14 5 Application information . 15 5.1 Input capacitor selection 15 5.2 Inductor selection . 16 5.3 Output capacitor selection 17 5.4 Compensation network . 18 5.4.1 Type III compensation network . 19 5.4.2 Type II compensation network 23 5.5 Thermal considerations 27 5.6 Layout considerations . 28 5.7 Application circuit . 30 6 Package information 34 2/37 DocID13004 Rev 7