L9386MD datasheet(8/10 Pages) STMICROELECTRONICS

8 / 10 page

CIRCUIT DESCRIPTION

The L9386MD is a dual low side driver for induc-

tive loads like valves in automotive environment.

The device is enabled by a common CMOS com-

patible ENABLE high signal. The internal pull

down current sources at the ENABLE and INPUT

pins protect the device in open input conditions

against malfunctions. An output slope limitation

for du/dt is implemented to reduce the EMI. An in-

tegrated active flyback voltage limitation clamps

the output voltage during the flyback phase to

50V.

Each driver is protected against short circuit and

thermal overload. In short circuit condition the

output will be disabled after a short delay time

tDOL to suppress spikes. This disable is latched

until a negative slope occure at the correspondent

input pin. The thermal disable for TJ > 175

°Cof

the output will be reseted if the junction tempera-

ture decreases about 20

°C below the disable

threshold temperature.

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

≥ 20KΩ,RL

>38

Ω) in ON and OFF conditions. The diagnostic

operates also in the extended supply voltage rang

of 4.5V

≤ VS ≤ 32V.

Also the output voltages VO1,2 are compared

against each other in OFF condition with a fixed

offset of

∆VOUV 1,2 to recognize GND bypasses.

To suppress mail

∆VO diagnoses during the fly-

back phases of the compared output, the

∆VO di-

agnostic includes a latch function. Reaching the

flyback clamping voltage VOC the diagnostic sig-

nal is reseted by a latch. To activate again this

kind of diagnostic a low signal at the correspon-

dent INPUT or the ENABLE pin must occur (see

also Fig.3).

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 also page 7 diagnostic ta-

ble).

The diagnostic output is also protected against

short to UDmax. Oversteping the over load current

threshold IOo, the output current will be limited in-

ternally during the diagnostic overload delay

switch-off time tDOL.

OUT1

OUT2

Z VALVE

V Batt

Channel 1

Channel 2

Output

Control

Overtemp

Delay

Timer

Overload

Openload

GND

DIAG2

IN2

DIAG1

IN1

Controller

+5V

R O

Diagnostic

Control

µ P

Figure 5: Application circuit diagram.

L9386MD

8/10

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