LED7707 STMicroelectronics, LED7707 Datasheet - Page 23

• Manufacturer Part Number: LED7707
• Description: LED Drivers 6-ROW 85mA LED DRIV BOOST REG LCD PANEL
• Manufacturer: STMicroelectronics

Specifications of LED7707

• High Level Output Current: 85 mA
• Operating Supply Voltage: 4.5 V to 36 V
• Maximum Supply Current: 1 mA
• Maximum Power Dissipation: 2.3 W
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Package / Case: VFQFPN-24
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LED7707
5.3.4
Figure 16
AVCC.
At the point marked as “1” in
point on the output voltage is increased as long as the output voltage reaches the floating
row detection threshold (see
faulty row is disconnected and the device keeps on working only with the remaining rows.
Figure 16. Open channel detection (MODE to AVCC)
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.
A 100 µs masking time is introduced to support ESD capacitors eventually connected
across the LEDs strings.
If the MODE pin is low, the fault threshold is V
row is higher than this threshold for more than 100 μs, 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 LED short-circuit protection is disabled.
The LED7707 simply keeps on regulating the set current without affecting the FAULT pin.
Despite the higher power dissipation, this option is useful to avoid undesired triggering of
the shorted-LED protection simply due to the high voltage drop spread across the LEDs.
Figure 17
shows an example of open channel detection in case of MODE connected to
shows an example of shorted LED detection in case MODE is connected to GND.
Figure 16
Section 5.1.3 on page 13
, the row opens (row current drops to zero). From this
TH,FAULT
2
2 2
). Then (point marked as “2”) the
= 4.0 V. When the voltage across a
1
1 1
Operation description
TH,FAULT
, the device
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