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AS8530
Datasheet - Application In form atio n
8.2 Wake-Up
If the regulator is put into sleep/standby mode, it can be woken up with the BUS interface. A transition on the BUS (high to low) with a minimum
predefined low time (twake) puts the regulator into normal mode.
8.3 Over-Temperature Shutdown
If the junction temperature increases beyond Tsd the over-temperature recognition will be activated and the regulator voltage will be switched off.
The VCC voltage drops down, the reset state is entered and the bus transceiver is switched off (recessive state). After TJ falls below Tret, the
AS8530 will be initialized again. This initialization starts independently from the voltage levels on EN and BUS. Within the thermal shutdown
mode, the transceiver cannot switch to the normal mode either with local or with remote wake-up. The operation of the AS8530 is possible
between TJ (125C) and the switch off temperature Tsd, but small parameter differences can appear. After over-temperature switch-off, the IC
initializes as explained in
Initialization on page 18. The low slew mode for LIN Transceiver has to be selected again on re-initialization, if
necessary.
8.4 LIN BUS Transceiver
The AS8530 has an integrated bi-directional bus interface device for data transfer between LIN bus and the LIN protocol controller. The
transceiver consists of a driver with slew rate control, wave shaping and current limitation and a receiver with high voltage comparator followed
by a de-bouncing unit.
8.4.1 Transmit Mode
During transmission the data at the pin TX will be transferred to the BUS driver to generate a bus signal. To minimize the electromagnetic
emission of the bus line, the BUS driver has an integrated slew rate control and wave shaping unit.
Transmitting will be interrupted in the following cases:
Sleep mode
Thermal Shutdown active
Master Reset (VSUP < Vsuvr_on)
The recessive BUS level is generated from the integrated 30k pull up resistor in serial with an active diode This diode prevents the reverse
current of VBUS during differential voltage between VSUP and BUS (VBUS>VSUP). No additional termination resistor is necessary to use the
AS8530 in LIN slave nodes. If this IC is used for LIN master nodes it is necessary that the BUS pin is terminated via an external 1k
Ω resistor in
series with a diode to VBAT.
Table 4. VSUP>Vsuvr_on and VCC<Vuvr_on
Block
Output Signal
TRANSCEIVER = Enabled (disabled only during initial VSUP ramp-up)
LIN = high-z, RX = follows V
LDO = Enabled (disabled only during initial ramp-up)
VCC = low
RELAY DRIVER = Enabled
LDRIVE1 = high, LDRIVE2 = high
RESET = Enabled
RESET = high-z
RESISTIVE DIVIDER = Enabled
VBAT= high, VBAT_DIV = enabled
Table 5. VSUP<Vsuvr_on
Block
Output Signal
TRANSCEIVER = Disabled
LIN = high-z, RX = high-z
LDO = Disabled
VCC = low
RELAY DRIVER = Disabled
LDRIVE1 = high, LDRIVE2 = high
RESET = Disabled
RESET = high-z
RESISTIVE DIVIDER = Disabled
VBAT = high, VBAT_DIV = low