L9300 datasheet(32/182 Pages) STMICROELECTRONICS

32 / 182 page

A dedicated disable SPI bit TRKn_DIS (default condition: track enabled) is present and it can be used to avoid

thermal on/off oscillations in case the short on output pin cannot be removed.

Figure 14. TRK regulators

TRK1

VBATP

Control

loop

Driver

TRK1

TRK_SEL

VDD1

GADG1107170903PS

8.5.2

WSI configuration

Functional description

If TRK_SEL pin is grounded, the device provides 4-wheel speed sensor interfaces on TRKn pins: the status of

each sensor is reported to the microcontroller via the SPI. The input signal of an active sensor is a rectangular

signal with variable pulse width and output currents of 2 levels (7/14 mA) or 3 levels (7/14/28 mA) depending on

the sensor itself. The sensor types are standard active 2-level wheel speed sensors (7/14 mA).

A simplified block diagram of the interface is shown below. The interface supply is given on the VDD1 pin. The

circuitry consists of a power interface that mirrors current flowing in the external sensor and transmits this current

information to the decoder, which produces a digital value for each remote sensor channel. Decoded data are

then output through the Remote Sensor Data Registers (WSIRSDRx). Received signals can be processed to

the corresponding discrete logic output pin DOUT1-DOUT4. The power interface also contains error detection

circuitry; when a fault is detected, the error code is stored in a global SPI data buffer in the Remote Sensor Data

Registers (WSIRSDRx).

L9300

TRK 1, 2, 3, 4

DS12258 - Rev 4

page 32/182

L9300 Datasheet(PDF) 32 Page - STMicroelectronics