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L9346

QUAD INTELLIGENT POWER LOW SIDE SWITCH

STMicroelectronics 

L9346

CIRCUIT DESCRIPTION

The L9346 is a quad low side driver for inductive

loads like valves in automotive environment. The

internal pull down current sources at the EN-

ABLE and INPUT pins assure in case of open in-

put conditions that the device is switched off. An

output voltage slope limitation for du/dt is imple-

mented to reduce the EMI. An integrated active

flyback voltage limitation clamps the output volt-

age 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 reseted if the junction

temperature decreases about 20°C below the dis-

able threshold temperature.

The overtemperatureinformation is stored until IN = L.

For the real time error diagnosis the voltage and

the current of the outputs are compared with in-

ternal fixed values VOUV for OFF and IOUC for ON

conditions to recognize open load (RL ≥ 20 KΩ,

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

Figure 3. Diagnostic Overload Delay Time

V IN

5V

offset of ∆VOUV to recognize load bypasses. To

suppress the ∆VOUV diagnoses during the flyback

phases of the compared output, the ∆VOUV diag-

nostic includes a latch function.

Reaching the flyback clamping voltage VOCL the

diagnostic signal is reseted by a latch. To activate

again this kind of diagnostic a low signal at the

correspondent INPUT or the ENABLE pin must

be applied (see also Fig.3). The outputs 1 and 4

are compared for ∆VOUV and also outputs 2 and 3

are compared.

The diagnostic output level in connection with dif-

ferent ENABLE and INPUT conditions allows to

recognize different fail states, like overtemp, short

to VSS, short to GND, bypass to GND and dis-

connected load (see diagnostic table).

The diagnostic output is protected against short

circuit. Exceeding the over load current threshold

IOOC, the output 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 fail-

ures of the functionality.

t

IO

I OOL

5A

3A

I OUC

t

t DOL

VD

5V

t

8/13

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