L99LDLH32 datasheet(21/142 Pages) STMICROELECTRONICS

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DS12879 Rev 6

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L99LDLH32

Functional description

141

Functional description

5.1

Operating modes

The L99LDLH32 features different operating modes. The related device states are reported

in Figure 6 and well detailed in the following sub-chapters.

There are 2 bits for safe transition between different modes: BUSMODE and GOSTBY

configuration bits (see RAM memory map, Chapter 7) are used to set, leave and check

device Normal / Bus operating mode.

A dedicated pattern through CAN FD Light compatible interface is used to wake-up and to

sleep the device. On top of that, device can be opportunely woken up or sent to sleep also

through DIN pin as well as through BUSMODE / GOSTBY bits respectively.

As the device potentially controls safety critical functions such as tail light and turn

indicators, built-in features are integrated to support a high level of functional safety on

application level. The L99LDLH32 features a programmable timeout watchdog by

WD_CONF (2 bits - see FTP/RAM memory map, Chapter 7), a monitoring of the watchdog

counter by WD_STATUS (2 bits - see RAM memory map, Chapter 7), a Fail Safe and a Direct

Input mode.

To keep the device in Normal / Bus mode, a watchdog trigger bit (WD_TRIG<0> - see RAM

memory map, Chapter 7) is cyclically toggled within the programmable watchdog timeout

period. In case of watchdog failure, the WD_FAIL bit (see RAM memory map, Chapter 7) is

set and the device leaves Normal/Bus mode operation to enter Fail Safe mode.

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