AN3981 datasheet(29/54 Pages) STMICROELECTRONICS

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AN3981

STP24DP05

Doc ID 022217 Rev 1

29/54

as an “Error status code” coming out of the SDO pin (see Figure 32), with “0” logic level

indicating a faulty channel, whereas a “1” logic level indicates a “good” channel.

Figure 32.

Error status code

The device can enter error detection mode in two ways:

setting low the DM pin

providing a logic sequence on the

and LE pins.

4.6.1

Error detection through the DM pin

As shown in Figure 33, the device enters error detection mode when the DM pin is set low.

The error detection is performed correctly when the

pin is set low for at least 1 µs.

When the DM and

pins are set high again, the error status code is available at the

SDO pin. 24 CLK cycles are necessary to make the device shift out of the complete error

status code.

Table 4.

Detection conditions

Detection result

IODEC

(1) = 0.4·I

(2)

IODEC is the detected output current in detection mode.

IO is the programmed output current.

Open channel or output short to GND detected

IODEC = 0.4·IO

No error detected

VO = 2.6 V

Short on LED or short to LED supply voltage

VO = 2.4 V

No error detected

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AN3981 Datasheet(PDF) 29 Page - STMicroelectronics