L6480 datasheet(29/73 Pages) STMICROELECTRONICS

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L6480

Functional description

Doc ID 023278 Rev 3

29/73

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 VADCIN falls below the VADC,UVLO value the

UVLO_ADC flag is forced low and it is kept in this state until the ADCIN voltage is greater

than VADC,UVLO and a GetStatus command is sent to the device.

The ADCIN undervoltage event doesn’t turn off the gates 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.

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 Tj(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 Tj(WRN)Rel threshold.

When the Tj(OFF)Set threshold is reached, all the gates are turned off and the gate driving

circuitry is disabled (Miller clamps are still operative). This condition expires when the

temperature falls below the Tj(OFF)Rel threshold.

When the Tj(SD)OFF threshold is reached, all the gates are turned off using Miller clamps, the

internal VCC voltage regulator is disabled and the current capability of the internal VREG

voltage regulator is reduced (thermal shutdown). In this condition logic is still active (if

supplied). The thermal shutdown condition only expires when the temperature goes below

Tj(SD)ON.

The thermal condition of the device is shown by TH_STATUS bits in the STATUS register

(Table 10).

Table 9.

UVLO thresholds

UVLOVAL

Low-side gate driver supply turn-off threshold

(VCCthOff)

6.3 V

10 V

Low-side gate driver supply turn-on threshold

(VCCthOn)

6.9 V

10.4 V

High-side gate driver supply turn-off threshold

(

ΔVBOOTthOff)

5.5 V

8.8 V

High-side gate driver supply turn-on threshold

(

ΔVBOOTthOff)

6 V

9.2 V

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