AST1S31HF Up to 4 V, 3 A step-down 2.3 MHz switching regulator for automotive applications Datasheet - production data Applications Designed for automotive systems Battery powered applications Car body applications Description The AST1S31HF is an internally compensated Features 2.3 MHz fixed frequency PWM synchronous step- AECQ100 qualified down regulator. The AST1S31HF operates from 2.8 V to 4 V input, while it regulates an output 3 A DC output current voltage as low as 0.8 V and up to V . IN 2.8 V to 4 V input voltage The AST1S31HF device integrates a 70 m high- Output voltage adjustable from 0.8 V side switch and a 55 m synchronous rectifier 2.3 MHz switching frequency allowing very high efficiency with very low output voltages. Internal soft-start and enable Integrated 70 m and 55 m power MOSFETs The peak current mode control with internal compensation deliver a very compact solution All ceramic capacitor with a minimum component count. Power Good (POR) The AST1S31HF is available in a 3 mm x 3 mm, Cycle-by-cycle current limiting 8-lead VFDFPN package. Current foldback short-circuit protection VFDFPN 3 x 3 - 8L package Figure 1. Application circuit / 1 92 87 6 9, : 1 6: 9, 1 5 &LQBD 67 6 +) (1 &RX W 3* Z QBV & L 5 August 2020 DocID026968 Rev 4 1/33 This is information on a product in full production. www.st.com *1 9)% 9,Contents AST1S31HF Contents 1 Pin settings 4 1.1 Pin connection 4 1.2 Pin description 4 2 Maximum ratings 5 2.1 Thermal data . 5 2.2 ESD performance 5 3 Electrical characteristics . 6 4 Datasheet parameters over the temperature range 7 5 Functional description . 8 5.1 Output voltage adjustment . 9 5.2 Soft-start 10 5.3 Error amplifier and control loop stability 10 5.4 Overcurrent protection . 15 5.5 Enable function 17 5.6 Light-load operation . 17 5.7 Hysteretic thermal shutdown 17 6 Application information . 18 6.1 Input capacitor selection 18 6.2 Inductor selection . 19 6.3 Output capacitor selection 20 6.4 Thermal dissipation . 21 6.5 Layout consideration 22 7 Demonstration board . 24 8 Typical characteristics 26 9 Package information 29 2/33 DocID026968 Rev 4