www.austriamicrosystems.com/Lin_CompanionIC/AS8530

Revision 1.1

15 - 32

AS8530

Datasheet - Detailed Descr i p ti on

Figure 5. Window Watchdog Trigger

7.7 LIN Transceiver

The transceiver provides short circuit limitation, hardware watchdog and over temperature shut down features. The TX watchdog timer is active

when TX is pulled low (active). As soon as the TX watchdog timeout occurs, the LIN bus is released from dominant state to recessive state. The

available to protect it from back supply from bus line.

The LIN transmitter has the basic functionality of relaying the data from the micro-controller on to the LIN. The data on the LIN needs to have

controlled slew to have reduced EMI. The receiver relays the data from the LIN to the micro-controller. This transmitter has optimized EMC

performance across different loading conditions conforming to the LIN 2.1 standards. The wake-up detects a wake up event on the LIN.

7.8 Operating Modes and States

The AS8530 provides four main operating modes “normal”, “sleep/stand-by” (programmed by OTP), “temporary shutdown” and “thermal

shutdown”. The LIN transceiver can be programmed to operate with lower slew in the normal mode. Refer to Table 3 for a detailed description on

transition for each mode.

7.8.1 Normal Mode

This is the mode after the power-up. In normal mode, LDO, LIN Transceiver, Window Watchdog, Resistive divider and the line drivers are all

turned on. All the blocks are completely functional. LDO is now capable of delivering maximum load current possible as per the device

specifications. The LIN Transceiver is capable of sending the TX data from microcontroller to the LIN bus at a maximum rate of 20Kbps. EN

signal is set to high and LIN, TX, RX pins can be driven into dominant (low) or recessive (high) states. If the junction temperature increases more

7.8.2 Standby Mode

Standby mode is a functional low-power mode where LIN Transceiver is disabled. The LIN wake-up circuit and over-temperature monitor circuit

is enabled. Window watchdog, TX timeout watchdog, Resistive divider, relay driver circuits are disabled. EN pin held low in this mode. TX pin is

7.8.3 Sleep Mode

As a factory programming option on request the AS8530 offers as a replacement to the standby mode with sleep mode. Sleep mode is the most

down to zero. The LIN wake-up circuit, oscillator and over-temperature monitor circuit is active. LIN bus is in recessive state (high). Only wake-

up possible is through remote wake-up, through LIN pin, pulling it to dominant state for 100µs typical (low), can change the state of the system.

Period

Non-Service time (WD_TCL)

Service time (WD_TSV)

Trigger restart period

Trigger via SPI

Last trigger point

Earliest possible trigger point

(System will not RESET)

Latest possible trigger point

(System will not be RESET)

50 %

100 %

Valid Trigger point

(System will not be RESET)

Unwanted trigger point

(System will be RESET)