BD9421F_15 Datasheet, PDF (9/31 Pages) Rohm – White LED Driver for large LCD Panels (DCDC Converter Type)

BD9421F
Datasheet
 Pin 21: RT
RT sets charge/discharge current determining frequency inside IC.
Only a resistor connected to RT determines saw-tooth wave frequency inside IC.
When RT=100kΩ,Frequency=150kHz(typ.).
For calculation example, please refer to section in “P15 – DC/DC drive frequency setting”.
When it reaches under VRT×0.90V(typ), DCDC operation will be stopped in order to prevent from high speed oscillation
when the RT resistance is shorted to GND. And when RT pin returns to normal state, DCDC also returns to operation.
 Pin 22: AGND
GND pin for analog system inside IC.
 Pin 23: STB
ON/OFF setting pin and allowed for use to reset the IC from shutdown.
※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).
 Pin 24: VCC
Power source pin of IC, which should be input in the range of 9 – 35 V.
Operation starts when VCC is 7.5V (TYP.) or higher and shuts down when VCC is 7.2 V (TYP.).
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25.Sep.2015 Rev.003