Datasheet

Functional description L6480
30/75 DocID023278 Rev 4
6.10 Undervoltage lockout (UVLO)
The L6480 provides a programmable gate driver supply voltage UVLO protection. When
one of the supply voltages of the gate driver (V
CC
for the low sides and V
BOOT
- V
S
for the
high sides) falls below the respective turn-off threshold, an undervoltage event occurs. In
this case, all MOSFETs are immediately turned off and the UVLO flag in the STATUS
register is forced low.
The UVLO flag is forced low and the MOSFETs are kept off until the gate driver supply
voltages return to above the respective turn-on threshold; in this case the undervoltage
event expires and the UVLO flag can be released through a GetStatus command.
The UVLO thresholds can be selected between two sets according to the UVLOVAL bit
value in the CONFIG register.
6.11 VS undervoltage lockout (UVLO_ADC)
The device provides an undervoltage signal of the integrated ADC input voltage (the
UVLO_ADC flag in the STATUS register). When V
ADCIN
falls below the V
ADC,UVLO
value the
UVLO_ADC flag is forced low and it is kept in this state until the ADCIN voltage is greater
than V
ADC,UVLO
and a GetStatus command is sent to the device.
The ADCIN undervoltage event doesn’t turn off the MOSFETs of the power bridges.
The motor supply voltage undervoltage detection can be performed by means of this
feature, connecting the ADCIN pin to VS through a voltage divider as described in
Section 7.5 on page 39.
6.12 Thermal warning and thermal shutdown
An integrated sensor allows detection of the internal temperature and implementation of
a 3-level protection.
When the T
j(WRN)Set
threshold is reached, a warning signal is generated. This is the thermal
warning condition and it expires when the temperature falls below the T
j(WRN)Rel
threshold.
When the T
j(OFF)Set
threshold is reached, all the MOSFETs are turned off and the gate
driving circuitry is disabled (Miller clamps are still operative). This condition expires when
the temperature falls below the T
j(OFF)Rel
threshold.
When the T
j(SD)OFF
threshold is reached, all the MOSFETs are turned off using Miller
clamps, the internal V
CC
voltage regulator is disabled and the current capability of the
internal V
REG
voltage regulator is reduced (thermal shutdown). In this condition logic is still
Table 9. UVLO thresholds
Parameter
UVLOVAL
01
Low-side gate driver supply turn-off threshold (V
CCthOff
) 6.3 V 10 V
Low-side gate driver supply turn-on threshold (V
CCthOn
) 6.9 V 10.4 V
High-side gate driver supply turn-off threshold (V
BOOTthOff
) 5.5 V 8.8 V
High-side gate driver supply turn-on threshold (V
BOOTthOff
) 6 V 9.2 V