SPSB081 datasheet(12/135 Pages) STMICROELECTRONICS

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Functional description

3.1

Supply Vs, Vsreg

VSREG supplies voltage regulators V1 and V2, all internal regulated voltages for analog and digital functionality,

LIN, CAN and the wake-up features. P-channel high side switches OUT1, OUT2, OUT3, OUT4 and fail-safe block

are supplied by VS. In case of VSREG pin disconnected, all power devices connected to VS are automatically

switched OFF.

Note:

After device startup, it is suggested to perform a status registers read&clear command to clean any spurious

error flags.

3.2

Voltage regulators

The SPSB081 contains one fully protected low drop voltage regulator (V1) and one low dropout tracking regulator

(V2), which are designed for very fast transient response and do not require electrolytic output capacitors for

stability. The two low drops out voltage regulators can provide 5 V or 3.3 V; the following table summarizes the

possible configurations of the two LDOs:

Table 6. Voltage regulators configuration

Configuration

P/N

V1 output voltage

(linear case)

V2 output voltage

(linear case)

V2 output voltage

(tracking case)

V2_TKR

SPSB0813

SPSB081C3

3.3 V

3.3 V(1)

YES

0 or 1

5.0 V

Not available

only 0

SPSB0815

SPSB081C5

5.0 V

3.3 V

Not available

only 0

5.0 V

YES

0 or 1

1. In this case, the CAN transceiver embedded inside the SPSB0813 shall be supplied by an external VREG at 5V via the CAN

supply pin.

The voltage regulator V2 can be configured by means of the V2_TKR bit in CR2 as a linear independent LDO

(V2_TKR=0, default) or as a tracker of the V1 voltage regulator (V2_TKR=1).

3.2.1

Voltage regulator: V1

The V1 voltage regulator provides 5 V (for SPSB0815 and SPSB081C5) or 3.3 V (for SPSB0813 and

SPSB081C3) supply voltage (configurable by OTP) and up to 250 mA continuous load current to supply

the system microcontroller and the integrated CAN transceiver. The V1 regulator is embedded in the power

management and fail-safe functionality of the device and operates according to the selected operating mode. The

V1 voltage regulator is supplied by pin VSREG.

In addition, the V1 regulator supplies the device internal loads. The voltage regulator is protected against overload

and overtemperature. An external reverse current protection must be provided by the application circuitry to

prevent the input capacitor from being discharged by negative transients or low input voltage. Current limitation

of the regulator ensures fast charge of external bypass capacitors. The output voltage is stable for ceramic load

capacitors ≥ 1µF.

In case the device temperature exceeds the TSD1 threshold, all outputs (OUTx, V2, LIN, CAN) are deactivated

except V1 regulator, which remains on. LIN and CAN transceivers are forced in "receive only" mode. Hence, the

microcontroller has the possibility for interaction or error logging. If the chip temperature exceeds TSD2 threshold

(TSD2>TSD1), V1 is deactivated and all wake-up sources (CAN, LIN, WU1, WU2, and timer) are disabled. After

tTSD, the voltage regulator will restart automatically. If the restart fails seven times within one minute the SPSB081

is forced into VBAT_standby mode. The status bit in SR1 Forced_Sleep_TSD2/V1SC is set.

In case of overvoltage an internal pulldown circuit is activated to limit the current accumulated in the external

capacitor.

SPSB081

Functional description

DS14048 - Rev 1

page 12/135

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