BD9206EFV データシートの表示（PDF） - ROHM Semiconductor

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BD9206EFV

LED Driver Series for LCD Backlight Simple Structure Constant Current Backlight Driver for LCD panels (Non-step type)

ROHM Semiconductor 

BD9206EFV

Technical Note

● Rise time and Fall time of LED Driver’s constant current

In the state of STBY=H, the rise time of constant current at the time of EN=L→H and the fall time at the time of EN=H→L

are as shown in the following table.

As shown in Fig.5, the constant current driver is formed in such a way that the NMOS of the driver output is made to be

operated or stopped by the EN signal.

Therefore, the rise time for the second time or later is shorter than the one for the first time because the electrical charge

of the capacitor for phase compensation is reopened from the charged state.

First time

Second time or later

Remarks

Rise time

2.9μs ± 7%

2.6μs ± 7%

The time interval between the

moment of EN=L→H and the

moment at which the ILED

reaches 90% of the set value

Fall time

0.7μs ± 11%

0.7μs ± 11%

The time interval between the

moment of EN=H→L and the

moment at which the ILED

reaches 10% of the set value

On the condition that VCC=Vo=24V, VF（LED）=3.2V 5-stage connection, RL=15Ω

■STBY, EN

At the time of STBY=L, it becomes the OFF mode, then only a portion of the circuit inside the IC is operating, so the circuit

current is restricted to 17μA (typ).

At the time of STBY=H, it becomes the Standby mode, then 5VREG is started and UVLO is released before the LED driver

gets into the state of Ready.

After that, if EN=L→H, then the current flows into the LED driver and the LED is lighted up.

Note: If STBY and EN are simultaneously made to be L→H, then the rising edge of the LED driver gets late because the

starting time of 5VREG is necessary.

If it is used after PWM dimming, then please let STBY=H beforehand and input the CLK to EN before using.

●Operation logic of LED driver

EN

STBY

L

H

L

Stop

Stop

H

Stop

Operation

STBY

EN

UVLO

TSD

LED

Driver

active : High

●Logic of LED driver protection circuit

Function

Stop

Operation

UVLO

VREG < 2.9V(typ)

VREG > 3.0V(typ)

TSD

Ta > 175℃

Ta < 155℃

■TEST terminal

TEST terminal is only used in ROHM’s testing process before delivery, so please use the IC with the terminal fixed at Low in

normal times.

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© 2009 ROHM Co., Ltd. All rights reserved.

6/12

2009.07 - Rev.A

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