L9800 datasheet(13/55 Pages) STMICROELECTRONICS

13 / 55 page

Power supply

The L9800 is fed by two supply voltages:

•

VBATT (general supply for analog and digital part)

•

VDDIO (supply for digital output buffers)

The VBATT supply line is connected to a battery feed and used for the driving circuitry of the power stages.

VBATT and VDDIO supply voltages have an undervoltage detection circuit, which prevents the activation of the

associated function in case the measured voltage is below the undervoltage threshold.

An undervoltage on the VBATT supply voltage prevents the activation of the power stages. All channels are

disabled, and are enabled again as soon as VBATT exits from the undervoltage condition.

An undervoltage on the VDDIO supply prevents any SPI communication. SPI read/write registers are reset to

default values.

The device drains all the needed current from the highest supply among the two.

Table 9. Supply ranges

Condition

VDDIO ≤ VDDIO(UV)

VDDIO > VDDIO(UV)

VBATT ≤ VBATT(UV)

Channels cannot be controlled

Channels can be controlled only if the VS_UV_MASK

bit is set to 1

SPI registers reset

SPI registers available

SPI communication not available

SPI communication available

Limp-home mode not available

Limp-home mode available (channels are off)

VBATT > VBATT(UV)

Channels cannot be controlled by SPI

Channels can be switched on and off

SPI registers reset

SPI registers available

SPI communication not available

SPI communication available

6.1

Operating modes

The L9800 has four operative states:

•

Sleep mode

•

Idle mode

•

Active mode

•

Limp-home mode

The transition between operation modes is determined according to the following levels and states:

•

Logic level at IDLE pin

•

Logic level at INn pins

•

PWM_SPI.OUTn bits state

•

CFG_1.ACT bit state

•

MAP_PWM.OUTn and PWM_SEL.OUTn bits state

The state diagram including the possible transitions is shown in the Figure 4. The behavior of the device as well

as some parameters may change depending on its operation mode. Furthermore, due to the undervoltage

detection circuitry, which monitors VBATT and VDDIO supply voltages, some changes within the same operation

mode can be seen accordingly.

In the case of VBATT < VBATT(UV_L) and IDLE = IN0 = IN1 = high channel outputs are disabled.

The operation mode of the device can be observed by:

•

Status of output channels

•

Status of SPI registers

•

Current consumption at VBATT pin (IVBATT)

L9800

Power supply

DS14041 - Rev 2

page 13/55

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