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A6985F Dataheets PDF



Part Number A6985F
Manufacturers STMicroelectronics
Logo STMicroelectronics
Description synchronous step-down switching regulator
Datasheet A6985F DatasheetA6985F Datasheet (PDF)

A6985F Automotive 38 V, 500 mA synchronous step-down switching regulator with 30 μA quiescent current Datasheet - production data HTSSOP16 (RTH = 40 °C/W) Features  AEC-Q100 qualified  0.5 A DC output current  4 V to 38 V operating input voltage  Low consumption mode or low noise mode  30 µA IQ at light-load (LCM VOUT = 3.3 V)  8 µA IQ-SHTDWN  Fixed output voltage (3.3 V and 5 V) or adjustable from 0.85 V to VIN  Adjustable fSW (250 kHz - 2 MHz)  Embedded output voltage supervisor  S.

  A6985F   A6985F


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A6985F Automotive 38 V, 500 mA synchronous step-down switching regulator with 30 μA quiescent current Datasheet - production data HTSSOP16 (RTH = 40 °C/W) Features  AEC-Q100 qualified  0.5 A DC output current  4 V to 38 V operating input voltage  Low consumption mode or low noise mode  30 µA IQ at light-load (LCM VOUT = 3.3 V)  8 µA IQ-SHTDWN  Fixed output voltage (3.3 V and 5 V) or adjustable from 0.85 V to VIN  Adjustable fSW (250 kHz - 2 MHz)  Embedded output voltage supervisor  Synchronization  Adjustable soft-start time  Internal current limiting  Overvoltage protection  Output voltage sequencing  Peak current mode architecture  RDSON HS = 360 m, RDSON LS = 150 m  Thermal shutdown Description The A6985F automotive grade device is a stepdown monolithic switching regulator able to deliver up to 0.5 A DC. The output voltage adjustability ranges from 0.85 V to VIN. The 100% duty cycle capability and the wide input voltage range meet the cold crank and load dump specifications for automotive systems. The “Low Consumption Mode” (LCM) is designed for applications active during car parking, so it maximizes the efficiency at light-load with controlled output voltage ripple. The “Low Noise Mode” (LNM) makes the switching frequency constant and minimizes the output voltage ripple overload current range, meeting the low noise application specification like car audio. The output voltage supervisor manages the reset phase for any digital load (µC, FPGA). The RST open collector output can also implement output voltage sequencing during the power-up phase. The synchronous rectification, designed for high efficiency at medium - heavy load, and the high switching frequency capability make the size of the application compact. Pulse by pulse current sensing on both power elements implements an effective constant current protection. Applications  Designed for automotive systems  Battery powered applications  Car body applications (LCM)  Car audio and low noise applications (LNM) August 2020 This is information on a product in full production. DocID027738 Rev 7 1/83 www.st.com Contents Contents A6985F 1 Application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.4 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.5 ESD protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4 Datasheet parameters over the temperature range . . . . . . . . . . . . . . . 14 5 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5.1 Power supply and voltage reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Switchover feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 5.2 Voltages monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 5.3 Soft-start and inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5.3.1 Ratiometric startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 5.3.2 Output voltage sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5.4 Error amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5.5 Output voltage line regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.6 Output voltage load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.7 High-side switch resistance vs. input voltage . . . . . . . . . . . . . . . . . . . . . . 27 5.8 Light-load operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 5.8.1 Low noise mode (LNM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 5.8.2 Low consumption mode (LCM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 5.8.3 Quiescent current in LCM with switchover . . . . . . . . . . . . . . . . . . . . . . . 34 5.9 Switchover feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 5.9.1 LCM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


1SS357 A6985F A6986F


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