L9800 datasheet(3/55 Pages) STMICROELECTRONICS

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Detailed description

The L9800 is an 8-channel IC, made of low-side drivers. All the outputs have typical RDS(ON) = 0.77 Ω at

TJ = 25 °C. The 16-bit serial peripheral interface (SPI) is used to control and diagnose the device and the loads.

The SPI interface provides daisy chain capability to assemble multiple devices in one SPI chain by using the

same number of microcontroller pins.

This device is designed for low supply voltage operation, it is able to maintain its functionality at low battery

voltage (VBATT ≥ 3 V). The SPI communication, including the ability to program the device, are present only

when the digital power supply is available (VDDIO ≥ 3 V).

The L9800 has two input pins (IN0 and IN1) respectively connected by default to the outputs OUT2 and OUT3,

making them controllable even when the digital supply voltage is not available. Thanks to the input mapping

functionality, it is possible to connect the input pins to different outputs, or to assign more outputs to the same

input pin. In this case, when the device is in fail-safe mode (limp-home), more channels can be controlled with

one signal applied to one input pin.

In limp-home mode the IN0 is mapped on channel 2 and IN1 is mapped on channel 3. When the IDLE pin is “low”,

it is possible to activate the two channels using the input pins independently from the presence of the digital

supply voltage VDDIO.

The device provides diagnosis of the load by detecting the open-load in the off state and the short-circuit. For

diagnosis of the off state (triggered by the SPI request), two current sources (pull-up and pull-down current) are

activated in two separate steps. The device detects an abnormal voltage on the output and, in case of fault

detection, it is able to differentiate open-load from short condition.

Each output stage is able to avoid short circuits. In case of overload, the affected channel is switched off with an

increased slew rate (gate kill) when the overload detection current IL(OVLn) is reached and can be reactivated via

SPI after clearing the register in which the fault is registered.

In limp-home state, the channel linked to an input pin set to 'high' where an OVL fault is detected is automatically

restarted after the restart time of the tRETRY output.

Temperature sensors are available for each channel to protect the device in case of over-temperature in the on

condition.

The power transistors are built by N-channel power MOSFET. The device is integrated in Smart Power

technology.

L9800

Detailed description

DS14041 - Rev 2

page 3/55

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