L9952GXP datasheet(16/68 Pages) STMICROELECTRONICS

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Description

L9952GXP

16/68

Doc ID 13518 Rev 5

2.5

Wake up inputs

The de-bounced digital inputs WU1...WU4 can be used to wake up the L9952GXP from

standby modes. These inputs are sensitive to any level transition (positive and negative

edge)

For static contact monitoring, a filter time of 64 µs is implemented at WU1-4. The filter is

started when the input voltage passes the specified threshold. At Vin > 1V and Vin < (Vs –

2V), a Wake-up request is processed. During Wake-up request, the internal oscillator and

other circuit blocks are activated in order to allow more accurate monitoring of the inputs.

In addition to the continuous sensing (static contact monitoring) at the wake up inputs, a

cyclic wake up feature is implemented. This feature allows periodical activation of the wake-

up inputs to read the status of the external contacts. The periodical activation can be linked

to Timer 1 (0.5sec to 4.0sec in 0.5sec steps) or Timer 2 (50ms). The input signal is filtered

with a filter time of 16us after a programmable delay (80us or 800us). A Wake-up will be

processed if the status has changed versus the previous cycle.

The Outputs OUT_HS and OUT1-4 can be used to supply the external contacts with the

timing according to the cyclic monitoring of the wake-up inputs.

If the wake-up inputs are configured for cyclic sense mode (Icxx in control register 2), the

same input filter timing (Timer1 or Timer2) and the corresponding input filter delay (control

external contact switches.

In Standby mode, the inputs WU1-4 are SPI configurable for pull-up or pull-down current

source configuration according to the setup of the external contacts (pull-up for active low

contacts, pull-down for active high contacts). In active mode the inputs have a pull down

resistor of 100 kOhm (typ).

In Active mode, the input status can be read by SPI (Status Register 0). Static sense should

be configured (Control Register 2) before the read operation is started (In cyclic sense

configuration, the input status is updated according to the cyclic sense timing; Therefore,

reading the input status in this mode may not reflect the actual status).

2.6

Hall sensor ports: WU3,4, Dig_Out 3,4

Applications like Hall sensor outputs need high processing speed. The 12V signals

connected to the wakeup inputs WU3 and WU4 can be looped through to the digital outputs

Dig_Out 3 and Dig_Out 4 (5V) in order to avoid read out of the input state by SPI.

The setup is programmable by SPI.

The open load states of the High Side Drivers OUT1 and OUT2 can be looped through the

digital outputs Dig_Out3 and Dig_Out4 without delay. In addition, the status of OUT1 and

OUT2 can be accessed through the SPI interface. This feature is intended for 2-pin HALL

sensors. Open Load information is only valid during ON state.

The Open Load threshold at pins OUT1...4 can be switched from IOLD1 = 2mA to

IOLD2 = 8 mA via SPI .

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