L9733

Functional description

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4

Functional description

L9733 integrates 8 self-configuring outputs (OUT1-8) which are able to drive either

incandescent lamps, inductive loads (non-pwm'd, in pwm is necessary an external diode to

reduce flyback power dissipation), or resistive loads biased to Vbat ( low side configuration)

or to GND (high side configuration). These outputs can be enabled and disabled via the SPI

bus. Each of these outputs has a short circuit protection (with 0.8-2.4 Amps threshold)

selectable via SPI bus between a filtered switching OFF overcurrent protection or a linear

current limitation (default condition after power ON is switching OFF protection enabled).

An over-temperature protection as described in Section 2.1 is available for each outputs.

When a high side configured output is commanded OFF after having been commanded ON,

the source voltage will go to (VGND - 15V). This is due to the design of the circuitry and the

transconductance of the MOSFET. When a low side configured output is commanded OFF

after having been commanded ON, the output voltage will rise to the internal zener clamp

voltage (50 VDC minimum) due to the flyback of the inductive load.

Outputs 1-8 are able to drive any combination of inductive loads or lamps at one time.

Inductive loads for the L9733 can range from 35mH to a maximum of 325mH. The

recommended worst-case solenoid loads (at -40°C) are calculated using a minimum

resistance of 40

Ω for each output. The maximum single pulse inductive load energy the

L9733 outputs is able to be safely handle is 20mJ at -40°C to 125°C (Worst-case load of

325mH & 40

Ω).

4.1

Configurations for Outputs 1-8

The drain and source pins for each Output must be connected in one of the two following

configurations (see Figure 6).

4.1.1

Low Side Drivers

When any combination of Outputs 1-8 are connected in a low side drive configuration the

source of the applicable Output (Src1-8) shall be connected to ground. The drain of the

applicable Output (Drn1-8) shall be connected to the low side of the load.

4.1.2

High Side Drivers

When any combination of Outputs 1-8 are connected in a high side drive configuration the

Drain of the applicable Output (Drn1-8) shall be connected to Vbat. The source of the

applicable Output (Src1-8) shall be connected to the high side of the load.

4.2

Outputs 1-5

These five outputs can be used as either high or low side drives. The room temperature

Rdson of these outputs is 0.7

Ω. A current limited (100µA max) voltage generator is

connected to Src 1-5 for open load and short to GND detection when a low side configured

output is commanded OFF. Another current limited (100µA max if VDrn 1-5 > 60%Vbat,

280µA max if VDrn 1-5 < 60%Vbat) voltage generator is connected to Drn 1-5 for open load

and short to Vbat detection when a high side configured output is commanded OFF.

Drain pins of Outputs 1-5 (Drn1-5) are connected to the drains of the N channel MOSFET