LED7707 STMicroelectronics, LED7707 Datasheet - Page 22

• 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

Operation description
5.3.1
5.3.2
5.3.3
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FAULT pin
The FAULT pin is an open-collector output, (with 4 mA current capability) active low, which
gives information regarding faulty conditions eventually detected. This pin can be used
either to drive a status LED or to warn the host system.
The FAULT pin status is strictly related to the MODE pin setting (see
MODE pin
The MODE pin is a digital input and can be connected to AVCC or SGND in order to choose
the desired fault detection and management. The LED7707 can manage a faulty condition
in two different ways, according to the application needs.
device detects and handles the internal protections related to the boost section (over-
current, over-temperature and over-voltage) and to the current generators section (open and
shorted LEDs).
Table 6.
Open LED fault
In case a row is not connected or a LED fails open, the device has two different behaviors
according to the MODE pin status. If the MODE pin is high (i.e. connected to AVCC), the
FAULT pin is set high as soon as the device recognizes the event; the open row is excluded
from the control loop and the device continues to work properly with the remaining rows.
Thus, if less than six rows are used in the application, the MODE pin must be set high.
Connecting the MODE pin to SGND, the LED7707 behaves in a different manner: as soon
as an open row is detected the FAULT pin is tied low and the device is turned off. The
internal logic latches this status: to restore the normal operation, the device must be
restarted by toggling the EN pin or performing a power-on reset (POR occurs when the
voltage at the LDO5 pin falls below the lower UVLO threshold and subsequently rises above
the upper one).
Output over-voltage
Thermal shutdown
Internal MOSFET
LED short circuit
over-current
Open row(s)
FAULT
Faults management summary
FAULT pin LOW, device turned
latched condition (Vth = 4.0 V)
occurrence, latched condition
OFF (100s masking time),
Device turned OFF at first
FAULT pin LOW
MODE to GND
Automatic restart after 30 C temperature drop.
Device turned OFF, latched condition
FAULT pin LOW. device turned OFF.
Power MOS turned OFF
FAULT pin HIGH
FAULT pin LOW
Table 6
FAULT pin HIGH faulty row(s)
summarizes how the
MODE to VCC
disconnected.
Table 6
-
for details).
LED7707