SPSB081 datasheet(37/135 Pages) STMICROELECTRONICS

37 / 135 page

All high side outputs switch off in case of:

•

VS overvoltage and undervoltage (depending on configuration, see Section 3.13 Power supply fail)

•

Overcurrent (only the impacted high-side)

•

Overtemperature (TSD1)

•

Fail-Safe event

•

Loss of ground at SGND pin

In the case of overcurrent or overtemperature (TSD1 (SR1)) condition, the drivers will switch off. The related

status bit is latched and can be read and optionally cleared by SPI. The drivers remain off until the status is

cleared.

In case of overvoltage and undervoltage conditions, the drivers are switched off. The relative status bit is latched

and can be read and optionally cleared by SPI. If the VS_LOCK_EN bit is set to ‘1’, the drivers remain off

until the status is cleared. If the VS_LOCK_EN bit is set to ‘0’, the drivers switch on automatically if the error

condition disappears. Under-voltage and over-voltage shutdown can be disabled by setting < VS_UV_SD_EN >

respectively < VS_OV_SD_EN > to ‘0’. In case of open load condition, the appropriate status register (in SR4) is

set. The status can be read and optionally cleared by SPI. The high side outputs are not switched off in case of

open load condition.

Note:

The maximum voltage and current applied to the high-side outputs are specified in the ‘absolute maximum

ratings’. Appropriate external protection may be required in order to respect these limits under application

conditions.

Each of the standalone high-side driver outputs OUT1..4 can be also driven either with an internal generated

PWM signal or with an internal timer. OUT1..4 can be also directly driven with DIR/WU2 pin.

3.16

Open-load detection

The open-load detection monitors the load current in each activated output stage. If the load current is below

the open- load detection threshold (IOLDx) for at least tFOL the corresponding open-load bit is set in the status

3.17

Overcurrent detection

In the case of an overcurrent condition, a status flag is set in the corresponding status register. If the overcurrent

signal is valid for at least tBLK, the overcurrent flag is set and the corresponding driver switches off to reduce the

power dissipation and to protect the integrated circuit. If the overcurrent recovery bit of the output is cleared, the

microcontroller has to clear the status bits to reactivate the corresponding driver.

3.18

Current monitor

The current monitor sources a current image of the power stage output current at the current monitor pin, which

has fixed ratio (ICMr see Table 34. Watchdog) of the instantaneous current of the selected high-side driver. The

signal at output CM is blanked after switching on the driver until correct settlement of the circuitry. The bits

CM_SEL_x (CR6) define which of the outputs is multiplexed to the current monitor output CM. The current

monitor output allows a more precise analysis of the actual state of the load rather than the detection of an open

or overload condition. The current monitor output is enabled after the current-monitor blanking time, when the

selected output is switched on. If this output is off, the current monitor output is in high-impedance mode. The

current monitor can be turned on or off by selecting the corresponding setting for the CM on / off bit.

3.19

Constant current mode

For the OUT1, OUT2, OUT3, and OUT4 high-side drivers, it is available the CCM (constant current mode)

feature, which is conceived to provide a constant current to the related output. The CCM feature is configurable

via SPI, by setting the OUTx_CCM_EN bit (x = 1, 2, 3,4) in CR20; these bits can be set only if the related driver

is in OFF state and when the CCM is enabled, the overcurrent and short circuit detection of the related output is

switched OFF while its open load detection is always ON.

The CCM is automatically disabled after an expiration time tCCMtimeout.

The allowed sequences are:

•

Set OUTx_CCM_EN bit, then turn ON the related driver by SPI (the other configurations of the OUTx_y in

CR5 are ignored): driver starts in CCM for tCCMtimeout, then it switches to ON mode and the OUTx_CCM_EN

bit is automatically cleared;

SPSB081

Open-load detection

DS14048 - Rev 1

page 37/135

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