BD9422EFV_15 Datasheet, PDF (13/30 Pages) Rohm – White LED Driver for large LCD panel

BD9422EFV
Datasheet
●3.2 Protection Operation at FAIL Latch output (FAILMODE=L)
●3.2.1 List of the Threshold Function terminal（typ. condition）
Please decide the resistance divider of the various protection detection using the following table.
Protection
name
Detection
Pin name
Detection condition
PWM
Release condition
Protection type
LED Open
LEDx
LEDx < 0.2V(4clk)
SS>3V
High
LEDx > 0.2V(*1)
Stop the CH latch after the CP
charge is completed.
LED short
LEDx
LEDx > 5×VLSP(4clk)
SS>3V
High
LEDx < 5×VLSP(3clk)
Stop the CH latch after the CP
charge is completed.
UVLO
UVLO
UVLO < 2.3V
―
UVLO > 2.5V
Stop the system
OVP
SCP
OVP
OVP
OVP > 2.43V
―
OVP < 0.2V
―
OCP
CS
CS > 0.45V
―
It is possible to reset with the FAIL_RST terminal to release the latch stop.
OVP < 2.4V
OVP > 0.2V
CS < 0.45V
Stop the N output
Stop the N output.
Stop the system after the CP
charge is completed.
Stop the N output under the
detection.（Pulse by Pulse）
(*1) The release condition of OPEN protection is depend on its release timing.
No.
The timing of release of LEDx voltage (LEDx
0.2V)
The release condition
1
LED pin voltage is released during PWM=H.
LED pin voltage is normal range during 3clk(3 positive edge)
As PWM=L, LED pin voltage do not exceed Short
2
LED pin voltage is released during PWM=L.
protection voltage (VLSP) during more than 3clk. or
PWM positive edge is input when LED pin voltage do not
exceed VLSP for more than 3clk.
●3.2.2 List of Protection function
Protection function
STB
LED Open
LED short
UVLO
DC/DC converter
Stop
Normal operation
(Stop when all LED
CH stop)
Normal operation
*1
Stop
Action when protection function is detected
LED driver
Soft-start
FAIL terminal
Stop
Stop after CP charge
(Latch operation)
Stop after CP charge
(Latch operation)
Stop
Discharge
Normal operation
Normal operation
Discharge
OPEN
DRAIN after the CP
charge is completed.
(Latch operation)
DRAIN after the CP
charge is completed.
(Latch operation)
GND
OVP
Stop N output
Normal operation
Normal operation
SCP
Stop N output
Stop after CP charge
(Latch operation)
Discharge after latch
OCP
Stop the N output
(Pulse by Pulse)
Normal operation
Normal operation
（*1）Short protection doesn't hang when becoming remainder 1ch. DCDC output falls as LED short.
OPEN
DRAIN after the CP
charge is completed.
(Latch operation)
OPEN
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TSZ22111・15・001
13/26
TSZ02201-0F1F0C100210-1-2
1.Sep.2015 Rev.006