BD9202EFS 데이터 시트보기 (PDF) - ROHM Semiconductor

부품명

상세내역

제조사

BD9202EFS

White backlight LED drivers

ROHM Semiconductor 

BD9202EFS

Technical Note

●Functional explanation

○ VREG

The fixed voltage of 5V is generated from VCC. It starts when it becomes EN=H.

UVLO (Under Voltage LOCK Out) is built in by VREG, When it is below 2.9V (typ)，the internal circuit stops.

When it is above 3.0V (typ), the internal circuit operation starts.

Please connect Creg=2.2 μ F to the VREG terminal, as a capacity for phase compensation.

In order to make IC heat generation decrease, impressing voltage into the VREG terminal from outside, it is possible

to decrease the loss with the regulator inside IC.

In this case, as for the impressing voltage, please impress that of above output voltage (5.25V5.5V) of the internal

regulator.

○ UVLO (Under Voltage Lock Out)

There are UVLO (REG) which detects VREG voltage① and UVLO (VCC) ② which detects VCC voltage in UVLO.

When each UVLO is below specified value, the internal circuit is made to stop. (The logic section is reset.)

Detecting circuit

Detection object

Detection

Cancellation

UVLO (VREG)

VREG

Below2.9V(typ) Above 3.0V(typ)

UVLO (VCC) VCC partial pressure input Below1.9V(typ) Above 2.0V(typ)

Please do not connect VCC terminal (> 5.25V) to the UVLO terminal (for VCC detection) directly. Because there is a

possibility of destruction, please be sure to input with partial pressure.

○ Fixed electric current driver

Fixed current value of the fixed electric current driver can be got by constant doubling the standard electric current

which is decided by the resistance (RSET) of being connected to ISET and the voltage which are input into the VSET

terminal. In addition continual electric current variable (analog modulated light) is possible by changing VSET voltage

from outside.

In addition, it is possible to do PWM modulated light by the fact that the data is input to the internal register from the

serial interface section. It is possible to set the Duty value of PWM for each channel.

・Setting of fixed current value

Fixed current value (DC value) of the LED driver is a relational expression below.

ILED=｛VSET/(RSET[kΩ]+20[kΩ]) ｝×7980－8 [mA]

However, when VSET voltage is above 2V, it reaches the point where it is clamped with 2V inside IC, fixed

current value above that does not increase.

In addition, please input VSET in the range of 0.6V-2.4V.

R SE T- ILE DC特h性aracteristic

160

140

120

100

80

Calculated value

Soli計d lin算e 値

(実線）

60

Surv実ey v測alu値e

40

(M( マarkーer)カ ー ）

20

0

0

100

200

300

400

500

600

700

800

R S E T[kΩ ]

・ VREF normal output

In VREG block, VREF (1.6V (typ.)of reference voltage output is provided.

The necessity of doing the voltage impression from outside by the fact that this terminal is connected to the VSET terminal is gone.

However, because the voltage variation of VREF is to be reflected on the variation of LED fixed electric current directly, so that

please pay attention to it.

www.rohm.com

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

6/19

2009.04 - Rev.A

Share Link: