Datasheet

L6470 Functional description
Doc ID16737 Rev 5 29/70
expired and a GetStatus command is sent to the IC (see Section 9.1.22 and 9.1.17). The
overcurrent event expires when all the Power MOSFET currents fall below the programmed
overcurrent threshold.
The overcurrent threshold can be programmed through the OCD_TH register in one of 16
available values ranging from 375 mA to 6 A with steps of 375 mA (see Tabl e 9 ,
Section 9.1.17).
It is possible to set whether an overcurrent event causes or not the MOSFET turn-off
(bridges in high impedance status) acting on the OC_SD bit in the CONFIG register (see
Section 9.1.21). The OCD flag in the STATUS register is raised anyway (see Table 3 4,
Section 9.1.22).
When the IC outputs are turned off by an OCD event, they cannot be turned on until the
OCD flag is released by a GetStatus command.
Attention: The overcurrent shutdown is a critical protection feature. It is
not recommended to disable it.
6.10 Undervoltage lockout (UVLO)
The L6470 provides a motor supply UVLO protection. When the motor supply voltage falls
below the V
SthOff
threshold voltage, the STATUS register UVLO flag is forced low. When a
GetStatus command is sent to the IC, and the undervoltage condition has expired, the
UVLO flag is released (see Section 9.1.22 and 9.2.20). The undervoltage condition expires
when the motor supply voltage goes over the V
SthOn
threshold voltage. When the device is
in undervoltage condition, no motion command can be performed. The UVLO flag is forced
low by logic reset (power-up included) even if no UVLO condition is present.
6.11 Thermal warning and thermal shutdown
An internal sensor allows the L6470 to detect when the device internal temperature exceeds
a thermal warning or an overtemperature threshold.
When the thermal warning threshold (T
j(WRN)
) is reached, the TH_WRN bit in the STATUS
register is forced low (see Section 9.1.22) until the temperature decreases below T
j(WRN)
and a GetStatus command is sent to the IC (see Section 9.1.22 and 9.2.20).
When the thermal shutdown threshold (T
j(OFF)
) is reached, the device goes into thermal
shutdown condition: the TH_SD bit in the STATUS register is forced low, the power bridges
are disabled bridges in high impedance state and the HiZ bit in the STATUS register is
raised (see Section 9.1.22).
The thermal shutdown condition only expires when the temperature goes below the thermal
warning threshold (T
j(WRN)
).
On exiting thermal shutdown condition, the bridges are still disabled (HiZ flag high); any
motion command makes the device exit from High Z state (HardStop and SoftStop
included).