BD9394FP Datasheet, PDF (9/31 Pages) Rohm – White LED Driver for large LCD Panels (DCDC Converter type)

BD9394FP, BD9394EFV
Datasheet
●Pin Function
○AUTO (HSOP20:1pin / HTSSOP-B24：1pin)
This sets up time till auto-restart time from the point of abnormal detection. Having 1uA constant current charge at
external capacitor connected to AUTO pin, it will start again when it becomes over 4.0V (The auto pin is shorted to GND,
this IC’s protection function operates latched off mode).
○Auto-restart period vs. AUTO capacitance (Ideal)
T _AUTO
=
4.0[V ] × C _AUTO
1.0 × 10 ^−6 [ A]
= 4.0 × 10 ⁶ × C _AUTO [sec]
○REG58 (HSOP20:2pin / HTSSOP-B24：2pin)
The REG58 pin is used in the DC/DC converter driver block to output 5.8V power. The maximum operating current is
15mA. Using the REG58 pin at a current higher than 15mA 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.
Please place the ceramic capacitor connected to REG58 pin (2.2uF～10uF) closest to REG58-GND pin.
○CS (HSOP20:3pin / HTSSOP-B24：3pin)
The CS pin has the following two functions:
1. DC/DC current mode current feedback function
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.
2. Inductor current limit function
The CS pin also incorporates the over current protection (OCP) function. If the CS pin voltage reaches 0.45V (Typ.) or
more, switching operation will be forcedly stopped.
○N (HSOP20:4pin / HTSSOP-B24：4pin)
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 REG58. ON resistances is 4.0Ω(typ.) in sorrce (H side), 3.0Ω(typ.) in sink (L side).
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.
○DCDC_GND (HSOP20:5pin / HTSSOP-B24：5pin)
The PGND pin is a power ground pin for the driver block of the output pin N.
○AGND (HSOP20:FIN1, FIN2 / HTSSOP-B24：19pin)
The GND pin is an internal analog circuit ground of the IC.
○LSP (HSOP20:6pin / HTSSOP-B24：6pin)
Terminal which sets LED SHORT detection voltage; the SHORT detection voltage is in a proportional relationship to LSP
set voltage and is set by the following equation:
LED
= 5 × VLSP [V ]
SHORT
LED_SHORT：LED detection voltage、VLSP：LSP setting voltage
LSP setting voltage should be made in the range of 0.8 to 3.0V. Set at 5 V (typ.) when LSP = OPEN.
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TSZ02201-0F1F0C100180-1-2
09.Nov.2012 Rev.002