L6985F 38 V, 500 mA synchronous step-down switching regulator with 30 A quiescent current Datasheet - production data Description The L6985F is a step-down monolithic switching regulator able to deliver up to 0.5 A DC. The output voltage adjustability ranges from 0.85V to VIN. Thanks to the P-channel MOSFET high-side power element, the device features 100% of the HTSSOP16 (R = 40 C/W) TH duty cycle operation. The wide input voltage range meets the specification for the 5 V, 12 V and 24 V power supplies. The Low Consumption Features Mode (LCM) is designed for applications active during the idle mode, so it maximizes the 0.5 A DC output current efficiency at the light-load with the controlled 4 V to 38 V operating input voltage output voltage ripple. The Low Noise Mode Low consumption mode or low noise mode (LNM) makes the switching frequency constant overload current range, meeting the low noise 30 A I at light-load (LCM V = 3.3 V) Q OUT application specification. The output voltage 8 A IQ-SHTDWN supervisor manages the reset phase for any Output voltage adjustable from 0.85 V to V digital load (C, FPGA). The RST open collector IN output can also implement output voltage Adjustable f (250 kHz - 2 MHz) SW sequencing during the power-up phase. The Embedded output voltage supervisor synchronous rectification, designed for high Synchronization efficiency at the medium - heavy load, and the high switching frequency capability make the size Adjustable soft-start time of the application compact. Pulse-by-pulse Internal current limiting current sensing on both power elements Overvoltage protection implements effective constant current protection. Output voltage sequencing Peak current mode architecture R = 360 m , R = 150 m DSON HS DSON LS Thermal shutdown Applications Designed for 12 V and 24 V buses Programmable logic controllers (PLCs) Decentralized intelligent nodes Sensors and low noise applications (LNM) February 2016 DocID027836 Rev 2 1/65 This is information on a product in full production. www.st.comContents L6985F Contents 1 Application schematic . 4 2 Pin settings 5 2.1 Pin connection 5 2.2 Pin description 5 2.3 Maximum ratings 6 2.4 Thermal data . 7 2.5 ESD protection 7 3 Electrical characteristics . 8 4 Functional description 12 4.1 Power supply and voltage reference 13 Switchover feature . 13 4.2 Voltages monitor 13 4.3 Soft-start and inhibit . 14 4.3.1 Ratiometric startup . 20 4.3.2 Output voltage sequencing 22 4.4 Error amplifier 22 4.5 Light-load operation . 23 4.5.1 Low noise mode (LNM) . 23 4.5.2 Low consumption mode (LCM) . 24 4.6 Switchover feature 28 4.6.1 LCM 28 4.6.2 LNM 28 4.7 Overcurrent protection . 29 OCP and switchover feature . 32 4.8 Overvoltage protection . 34 4.9 Thermal shutdown 35 2/65 DocID027836 Rev 2