Figure 10. Open load off-state

LOADX

VCC

PGND

IPU

SUPPLY RAIL

GROUND PLANE

APPLICATION BOARD

IPS4260L

.

.

.

.

.

.

LOAD

RPD

Open load

detection signal

+

-

VOL

-OFF

VCC

VZ

The voltage on LOADx pin (VLOADx) is internally compared with the VOLOFF threshold: if the related INx pin is

LOW and the VLOADX goes lower than VOLOFF then the open load condition is triggered. The fault condition is

reported on the OL pin and the fault reset occurs when load is reconnected. If the channel is switched ON by the

related INx pin, the fault condition is no longer detected.

In OFF state, the IPS4260L achieves the open load detection feature by forcing the internally generated current

IPU (= 20 μA) on the external pull-down resistor RPD. The following design rule has to be followed in order to set

the proper value of RPD:

Equation 3:

RPD<VOLOFFmin

IPU = VCC−4.5

IPU

(3)

Note:

When the load is connected the open load detection threshold must not be triggered:

Equation 4:

VLOADX=VCC * RPD

RPD+ RLOAD >VOLOFF max

(4)

Therefore:

Equation 5:

RPD>RLOAD* VOLOFFmax

VCC−VOLOFFmax

(5)

Note:

if two or more channels are parallelized then RPD must be calculated according to the n*Ipu (e.g. in case of 4

channels in parallel the total Ipu becomes 80uA).

6.5

GND wire break protection

GND wire break is intended as the disconnection event of the application board ground (where both SGND and

PGND signals are connected) from the system ground of the external supply rail (see fig 11 GND wire break,

where the shape between VZ and supply rail represents one of the application configurations: open circuit, short

circuit or an external TVS).

When this event happens, the supply voltage at Vcc pin decreases until Vuvoff is triggered and then all power

stages are turned off independently of the input status.

In case of inductive load, if the ground disconnection event happens while one or more channels are active:

IPS4260L

GND wire break protection

DS12305 - Rev 5

page 15/29