EVALED7706 STMicroelectronics, EVALED7706 Datasheet - Page 23

• Manufacturer Part Number: EVALED7706
• Description: EVALUATION BOARD FOR LED7706
• Manufacturer: STMicroelectronics

Specifications of EVALED7706

• Current - Output / Channel: 30mA
• Outputs And Type: 6, Non-Isolated
• Voltage - Output: 36 V
• Features: Dimmable, Extra 5V Output
• Voltage - Input: 4.5 ~ 36 V
• Utilized Ic / Part: LED7706
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6445

LED7706
5.3.4
Shorted LED fault
When a LED is shorted, the voltage across the related current generator increases of an
amount equal to the missing voltage drop of the faulty LED. Since the feedback voltage on
each active generator is constantly compared with a fault threshold V
detects the faulty condition and acts according to the MODE pin status.
If the MODE pin is low, the fault threshold is V
row is higher than this threshold, the FAULT pin is set low and the device is turned off. The
internal logic latches this status until the EN pin is toggled or a POR is performed.
In case the MODE pin is connected to AVCC, the fault threshold is set to 6 V. The LED7706
simply disconnects the rows whose voltage is higher than the threshold and the FAULT pin
is forced low. This option is also useful to avoid undesired triggering of the shorted-LED
protection simply due to the high voltage drop spread across the LEDs.
Figure 16
At the point marked as “1” in
across the current generator of the channel where the failed LED is connected increases by
an amount equal to the forward voltage of the faulty LED. Since the voltage across the
current generator is above the threshold (3.4 V in this case), the device is turned off and the
fault pin is set low (point “2”).
Figure 16. Shorted LED detection (MODE to GND)
shows an example of shorted LED detection in case MODE is connected to GND.
Figure 16
one LED fails becoming a short-circuit. The voltage
TH,FAULT
1
1
= 3.4 V. When the voltage across a
2
2
Operation description
TH,FAULT
, the device
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