L99PM72GXP datasheet(13/129 Pages) STMICROELECTRONICS

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L99PM72GXP

Detailed description

128

Detailed description

2.1

Voltage regulators

The L99PM72GXP contains two independent and fully protected low drop voltage

regulators, which are designed for very fast transient response and do not require

electrolytic output capacitors for stability.

The output voltage is stable with ceramic load capacitors

≥ 220 nF.

2.1.1

Voltage regulator: V1

The V1 voltage regulator provides 5 V supply voltage and up to 250 mA continuous load

current and is mainly intended for supply of the system microcontroller. The V1 regulator is

embedded in the power management and Fail_safe functionality of the device and operates

according to the selected operating mode.

It can be used to supply the internal HS CAN Transceiver via the CANSUP pin externally. In

case of a short circuit condition on the CAN bus, the output current of the transmitter is

limited to 100 mA and the transceiver is turned off in order to ensure continued supply of the

microcontroller.

In addition the regulator V1 drives the L99PM72GXP internal 5 V loads. The voltage

regulator is protected against overload and overtemperature. An external reverse current

protection has to 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

≥ 220 nF.

If the device temperature exceeds the TSD1 threshold, all outputs (OUTx, RELx, V2, LIN)

are deactivated except V1. Hence the micro controller has the possibility for interaction or

error logging. In case of exceeding TSD2 threshold (TSD2 > TSD1), also V1 is deactivated

(see Figure 23: Thermal shutdown protection and diagnosis). A timer is started and the

voltage regulator is deactivated for tTSD = 1 sec. During this time, all other wakeup sources

(CAN, LIN, WU1...3 and wake up of µC by timer) are disabled. After 1 sec, the voltage

regulator tries to restart automatically. If the restart fails 7 times, within one minute, without

clearing and thermal shutdown condition still exists, the L99PM72GXP enters the Forced

VBat_standby Mode.

In case of short to GND at "V1" after initial turn on (V1 <2 V for t > tV1 short) the

L99PM72GXP enters the Forced VBat_standby Mode. Reactivation (wake-up) of the device

can be achieved with signals from CAN, LIN, WU1..3 or periodic wake by timer.

2.1.2

Voltage regulator: V2

The voltage regulator V2 can supply additional 5 V loads (e.g. logic components or the

integrated HS CAN transceiver or external loads such as sensors or potentiometers. The

maximum continuous load current is 100 mA. The regulator is protected against:

•

Overload

•

Overtemperature

•

Short circuit (short to ground and battery supply voltage)

•

Reverse biasing

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