L99ASC03 datasheet(10/73 Pages) STMICROELECTRONICS

10 / 73 page

Device description

L99ASC03

10/73

DocID023504 Rev 7

Device description

2.1

Supply pins (VS, VSREG, VSMS)

The device has three different supply input pins. VS and VSREG have to be protected against

negative voltages, while VSMS is robust against negative voltages.

The two-stage charge pump is supplied from VS. External capacitors are used to achieve

high current capability of the charge pump. The gate drivers (for both high-side and low-side

MOSFETs) are supplied from the charge pump to ensure full drive of the external

MOSFETs.

The internal power-on reset (POR) circuitry and the VDD voltage regulator are supplied from

the VSREG pin. Some external protection has to be provided in the application for VS and

VSREG to prevent the capacitor connected to these pins from being discharged by negative

transients or low input voltage.

VSMS is used to monitor the power supply of the external MOSFETs and as a reference for

the BEMF detection.

2.1.1

VS, VSREG and VSMS overvoltage warning

In case any of the supply inputs reach the overvoltage warning threshold, the corresponding

overvoltage warning flag is set. This flag can be cleared by an SPI “Read & Clear” command

provided that the cause of the warning is no longer present.

2.1.2

VS, VSREG and VSMS overvoltage

In case any of the supply inputs reach the overvoltage threshold, the corresponding

overvoltage flag is set. This flag can be cleared by an SPI “Read & Clear” command

provided that the cause of the overvoltage is no longer present.

In case of VS and VSMS overvoltage, the gate drivers are disabled, along with other

functions (for further details see Table 5). VSREG overvoltage is used only for information.

2.1.3

VS, VSREG and VSMS undervoltage

In case any of the supply inputs reach the undervoltage threshold, the corresponding

undervoltage flag is set. This flag can be cleared by an SPI “Read & Clear” command

provided that the cause of the undervoltage is no longer present.

The Vs, VSMS and VSREG undervoltage flags are used only for information.

2.2

VDD (5V) voltage regulator

The device integrates a fully protected low-drop voltage regulator, which is designed for very

fast transient response.

The voltage regulator provides a 5 V output and a continuous load current up to 200 mA to

supply external devices (e.g.an external microcontroller). In addition, this regulator powers

the internal 5 V loads such as the I/O pins and the current-sense amplifier (CSA). The

voltage regulator is protected against overload and overtemperature. The output voltage is

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