BD9479FV ROHM [Rohm], BD9479FV Datasheet - Page 9

• Manufacturer Part Number: BD9479FV
• Description: White LED Driver for large LCD Panels (DCDC Converter type)
• Manufacturer: ROHM [Rohm]

●Pin Function
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TSZ22111・15・001
BD9479FV
○ ○ ○ ○ Pin 2:N
○ ○ ○ ○ Pin 3: PGND
○ ○ ○ ○ Pin 4: CS
Pin 25-32 : CL8 – CL1
○ ○ ○ ○ Pin 1: REG50
Pin 5: OVP
Pin 6: CP
Pin 7: LSP
Pin 8 :STB
Pin 9-16 :BS1-BS8
Pin 17-24 :PWM1 – PWM8
ON/OFF setting pin and allowed for use to reset the IC from shutdown.
High/Low level of PWM terminal is shown as follows:
ON/OFF terminal of LED driver pin.It inputs PWM dimming signal directly to adjust output DUTY dimming.
The N pin is used to output power to the external NMOS gate driver for the DC/DC converter in the amplitude range of
approx. 0 to 5V. Frequency setting can be made with a resistor connected to the RT pin. For details of frequency setting,
refer to the description of the ＜RT pin＞.
The PGND pin is a power ground pin for the driver block of the N output pin.
CS pin is current detect for DC/DC current mode inductor current control pin.
Current flowing through the inductor is converted into voltage by the current sensing resistor RCS connected to the CS
pin and this voltage is compared with voltage set with the error amplifier to control the DC/DC output voltage.
The CS pin also incorporates the overcurrent protection (OCP) function. If the CS pin voltage reaches 0.4V (Typ.) or
more, switching operation will be forcedly stopped.
In order to prevent the malfunction while OCP occurred in BD9479FV,it equipped with mask function.It mask OCP signal
within 200ns interval after N driver is outputted.
The OVP pin is an input pin for overvoltage protection and short circuit protection of DC/DC output voltage.When voltage
of it over 2.25V or higher,CP pin start to charge.When it over 2.5V(typ),it will control FB pin.When OVP pin voltage is
near 2.5V,DCDC output feedback will controlled by OVP pin voltage.
When OVP pin voltage<0.2V (typ.) or lower,short circuit protection (SCP) function is activated, and output of Gate driver
will become low immediately.
CP pin which sets the time from detection of abnormality until shutdown (Timer latch).It charges constant current
of 2.0uA to capacitor externally connected with CP pin and shuts down when it exceeds 2.5V(Typ.).
LED Short detect voltage setting pin.When LSP=OPEN, LSP pin voltage is 0.9V( typ), the BSx pin of LED SHORT detect
voltage is set to 9V.
The 10 times of LSP pin voltage is the BSx pin LED SHORT protection detect voltage.
Please set LSP pin input voltage range from 0.3V～3.0V.
※The IC state is switched (i.e., The IC is switched between ON and OFF state) according to voltages input in the STB
pin. Avoid using the STB pin between two states (0.8 to 2.0V).
The REG pin is used in the DC/DC converter driver block to output 5V power. The maximum operating current is 5mA.
Using the REG pin at a current higher than 5mA can affect the N pin output pulse, causing the IC to malfunction and
leading to heat generation of the IC itself. To avoid this problem, it is recommended to make load setting to the minimum
level.
LED DRIVER output pin.Please connect to Base Terminal of external PNP Tr.
LED ON state
LED OFF state
State
PWM= 2.0V~5.0V
PWM= －0.3V～0.8V
PWM Voltage
9/26
TSZ02201-0F1F0C100020-1-2
9.Aug.2012 Rev.001
Datasheet