L9377 Ver la hoja de datos (PDF) - STMicroelectronics

Número de pieza

componentes Descripción

Fabricante

L9377

DUAL INTELLIGENT POWER LOW SIDE SWITCH

STMicroelectronics 

L9377

CIRCUIT DESCRIPTION

The L9377 is a dual low side driver for inductive

loads like valves in automotive environment. The

device is enabled by a common CMOS compat-

ible 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°C of

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

> 38Ω) in ON and OFF conditions. The diagnostic

Figure 5: Application circuit diagram.

operates also in the extended supply voltage

range 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.

+5V

µP

Controller

IN1

DIAG1

EN

IN2

DIAG2

Channel 1

Z VALVE

OUT1

Output

Control

R

QS

Overtemp

Delay

Timer

Overload

Diagnostic

Control

Channel 2

Openload

VS

RO

OUT2

Z VALVE

V Batt

GND

8/9

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