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STLC5445

Figure 6. Typical Protection Diagram (only channel 0 and 1 shown)

FUNCTIONAL DESCRIPTION

WAn (n=0-3)

Drivers (output pins).

Each WAn output can sink up to 140mA. When the ESn input is High and the activation request

is approved by the internal control circuitry, the respective WAn output is internally connected

to VBAT through a DMOS switch and the low side sensing resistor.

WBn (n=0-3)

Resistor to BGND.

Each WBn output connects the wire B to ground through a 5W resistor used to perform the

longitudinal balance and the high side current sensing function.

WBPn (n=0-3) Protection diodes connection (see the block diagram at page 3).

Each channel of the STLC5445 has two internal, back to back connected diodes, whose clamp-

ing action can be used to protect the WBn outputs during lighting and power crossing events.

The diodes' clamping action is normally disabled and can be activated by connecting the WBPn

pin to BGND. In this case however, if the line current exceeds 57.5mA the forward drop across

the high side sensing resistor (and then across the diodes) reaches the diodes' conduction

threshold, strongly degrading the current limiting action and the longitudinal balance. For line

currents higher than 57.5mA external clamping elements must then be connected in place of

the internal diodes or in series to them in order to increase the clamping voltage value.

BGND

Battery ground.

DGND

Digital ground.

1

µF

1

µF

SM5908

2 x

SM6T68A

SM5908

16

ΩPTC

22

Ω

16

ΩPTC

22

Ω

16

ΩPTC

22

Ω

16

ΩPTC

22

Ω

TIP

RING

TIP

RING

CHANNEL's 1 OUTPUT

DRIVER's STAGE

CHANNEL's 0 OUTPUT

DRIVER's STAGE

D02TL549

Note: The 1

µF capacitors are required for output driver's stability