L9349 datasheet(6/12 Pages) STMICROELECTRONICS

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L9349

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DIAGNOSTIC TABLE

CIRCUIT DESCRIPTION

The L9349 is a quad low side driver for inductive loads like valves in automotive environment. The internal pull

down current sources at the ENable and INput pins assure in case of open input conditions that the device is

switched off. An output voltage slope limitation for du/dt is implemented to reduce the EMI. An integrated active

flyback voltage limitation clamps the output voltage during the flyback phase to 50 V.

Each driver is protected against short circuit at VOUT < 32V and thermal overload. In short circuit condition the

output will be disabled after a short delay time tDOL. The thermal disable for TJ > 180°C of the output will be

reset if the junction temperature decreases about 20°C below the disable threshold temperature.

The overtemperature, overload and groundloss information is stored until IN is low.

For the real time error diagnosis the voltage and the current of the outputs are compared with internal fixed val-

ues VOUV for OFF and IOUC for ON conditions to recognize open load (RL ≥ 20KΩ, RL > 38Ω) in OFF and ON

conditions.

Also the output voltages VO1- 4 are compared to each other output in OFF condition with a fixed offset of ∆VOUV

to recognize load bypasses. The

∆VOUV diagnoses is suppressed during the flyback phases of the compared

output. The outputs 1 and 4 are compared for

∆VOUV and also outputs 2 and 3 are compared.

The diagnostic output level in connection with different ENable and INput conditions allows to recognize differ-

ent fail states, like overtemp, short to VS, short to GND, bypass to GND and disconnected load (see diagnostic

table).

The diagnostic output is protected against short circuit. Exceeding the over load current threshold IOOC, the out-

put current will be limited internally during the diagnostic overload delay switch-off time tDOL.

The device complies the ISO pulses imposed to the supply voltage of the valves without any failures of the func-

tionality. Therefore some diagnostic functions are internal filtered. The following table shows the corresponding

filter time for each detected signal.

Conditions

OUT

DIAG.

Normal Function

off

GND short

VOtyp < 0.55VS

off

Load bypass

∆VO1-4/2-3 ≥ 1.25V

off

Open Load

IO1,2,3,4typ < 320mA

Tjtyp ≥ 190°C Overtemperature

off

Over Load

IOmin 1,2 > 5A

IOmin 3,4 > 3A

off

SGND or PGND loss

channel off

off

SGND or PGND loss

channel on

off

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