L6470PD datasheet(29/70 Pages) STMICROELECTRONICS

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L6470

Functional description

Doc ID16737 Rev 5

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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 Table 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 34,

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 VSthOff 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 VSthOn 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 (Tj(WRN)) is reached, the TH_WRN bit in the STATUS

and a GetStatus command is sent to the IC (see Section 9.1.22 and 9.2.20).

When the thermal shutdown threshold (Tj(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 (Tj(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).

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