Datasheet

Functional description L6470
30/73 DocID16737 Rev 7
Attention: The overcurrent shutdown is a critical protection feature. It is
not recommended to disable it.
6.10 Undervoltage lockout (UVLO)
The L6470 device 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 on page 55 and 9.2.20 on page 66).
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).
6.12 Reset and standby
The device can be reset and put into Standby mode through a dedicated pin. When the
STBY
\RST pin is driven low, the bridges are left open (High Z state), the internal charge
pump is stopped, the SPI interface and control logic are disabled and the internal 3 V
voltage regulator maximum output current is reduced to I
REG,STBY
; as a result, the L6470
heavily reduces the power consumption. At the same time the register values are reset to
default and all protection functions are disabled. STBY
\RST input must be forced low at
least for t
STBY,min
in order to ensure the complete switch to Standby mode.
On exiting Standby mode, as well as for IC power-up, a delay of up to t
logicwu
must be given
before applying a new command to allow proper oscillator and logic startup and a delay of
up to t
cpwu
must be given to allow the charge pump startup.