BD9422EFV_15 Datasheet, PDF (10/30 Pages) Rohm – White LED Driver for large LCD panel

BD9422EFV
Datasheet
Rise Time
800
700
600
500
400
300
200
100
0
0
0.5
1
1.5
VREF[V]
MEASURE
IDEAL
2
2.5
Figure 13.
1200
1000
800
600
400
200
0
0
Pulse Response Width
MEASURE
IDEAL
0.5
1
1.5
2
2.5
VREF[V]
Figure 14.
17pin. STB
ON/OFF setting terminal for IC, which can be used perform a reset at shutdown.
* The voltage of STB input in the sequence of VCC → STB.
* Voltage input in STB terminal switches the state of IC (IC ON/OFF). Using the terminal between the 2 states (0.8 to 2.0 V)
needs to be avoided.
18 to 23pin. PWM1 to PWM6
ON/OFF terminal of LED driver: it inputs PWM dimming signal directly to PWM terminal and change of DUTY enables
dimming. High/Low level of PWM terminal is shown as follows:
State
LED ON
LED OFF
PWM voltage
PWM= 2.0 to 20V
PWM= -0.3 to 0.8V
24pin.FAIL_RST
Reset terminal of the protection circuit and FAIL terminal:
Return the latch stopped protection block by setting the FAIL_RST to High. During High state, operation is masked by the
latch system protection.
25 to 30pin. S1 to S6, 35pin. VREF
S terminal is a connecting terminal for LED constant current setting resistor, output current ILED is in an inverse relationship
to the resistance value.
VREF terminal is a terminal for analog dimming; output current ILED is in a proportional relationship to the voltage value to
be input.
VREF terminal is assumed that it is set by dividing the resistance with a high degree of accuracy, VREF terminal inside the
IC is in open state (High Impedance). It is necessary to input voltage to divide the resistance from the output of REG9V or
use external power source. Using the terminal in open state needs to be avoided.
The relationship among output current ILED, VREF input voltage, and RS resistance has the following equation:
ILED  ^{VREF [V]}  0.2[A]　　
RS[Ω]
The voltage of S terminal is following equation:
VS  0.2 VREF [V ]　　
+
-
LED ^↓ILED
S 240mV
RS
VREF=1.2V, RS=2 [Ω]
ILED=120[mA]
Figure 15.
*Attention: Rises LED current accelerate heat generation of IC. Adequate consideration needs to be taken to thermal design
in use.
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TSZ22111・15・001
10/26
TSZ02201-0F1F0C100210-1-2
1.Sep.2015 Rev.006