A7987 Datasheet 61 V 3 A asynchronous step-down switching regulator with adjustable current limitation for automotive Features • 3 A DC output current • 4.5 V to 61 V operating input voltage • RDS(on) = 250 mΩ typ. • Adjustable fsw (250 kHz to 1.5 MHz) • Low IQ-SHD (11 µA typ. from VIN) • Low IQ (1 mA typ. - VIN 24V - VOUT 3.3V) • Output voltage adjustable from 0.8 V to VIN • Synchronization • Adjustable soft-start time • Adjustable current limitation • Low-dropout operation • VBIAS improves efficiency at light load • PGOOD open collector output • Output voltage sequencing • Digital frequency fold-back in short-circuit • Auto recovery thermal shutdown • Qualified following AEC-Q100 requirements ApplicationsProduct status link • Designed for 24 V automotive battery systems • Industrial and commercial vehicles A7987 Description The A7987 is a step down monolithic switching regulator able to deliver up to 3 A DC. The output voltage adjustability ranges from 0.8 V to VIN. The wide input voltage range and the almost 100% duty cycle capability meet the fail-safe specifications for industrial systems. The embedded switch-over feature on the VBIAS pin maximizes the efficiency at light load. The adjustable current limitation, designed to select the inductor RMS current in accordance with the nominal output current, and the high switching frequency capability make the size of the application compact. Pulse by pulse current sensing with digital frequency fold-back implements an effective constant current protection over the different application conditions. The peak current fold-back decreases the stress of the power components in heavy short-circuit condition. The PGOOD open collector output can also implement output voltage sequencing during the power-up phase. Multiple devices can be synchronized sharing the SYNCH pin to prevent beating noise for low noise requirements such as in infotainment applications. DS12928 - Rev 1 - March 2019 www.st.com For further information contact your local STMicroelectronics sales office. Document Outline Cover image Product status link / summary Features Applications Description 1 Application schematic 2 Block diagram 3 Pin settings 3.1 Pin connection 3.2 Pin description 3.3 Maximum ratings 3.4 Thermal data 3.5 ESD protection 4 Electrical characteristics 5 Functional description 5.1 Oscillator and synchronization 5.2 Soft-start 5.3 Error amplifier and light-load management 5.4 Low VIN operation 5.5 Overcurrent protection 5.6 Overtemperature protection 6 Application information 6.1 Input capacitor selection 6.2 Output capacitor selection 6.3 Inductor selection 6.4 Compensation network 6.4.1 Type II compensation network 6.4.2 Type III compensation network 6.5 Thermal considerations 6.6 Layout considerations 7 Demonstration board 8 Application ideas 8.1 Positive buck-boost 8.2 Negative buck-boost 9 Package information 9.1 HTSSOP16 package information 10 Ordering information Revision history
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