Datasheet

Datasheet

11/28

TSZ02201-0F1F0C100180-1-2

© 2012 ROHM Co., Ltd. All rights reserved.

09.May.2014 Rev.003

www.rohm.com

TSZ22111・15・001

BD9394FP, BD9394EFV

The SS pin is used to make setting of soft start time and duty for soft start. It performs constant current charge of 2.0 uA

to the external capacitor connected with SS terminal, which enables soft-start of DC/DC converter.

Since the LED protection function (OPEN/SHORT detection) works when the SS terminal voltage reaches 3.7 V (typ.) or

higher, it must be set to bring stability to conditions such as DC/DC output voltage and LED constant current drive

operation, etc. before the voltage of 3.7 V is detected.

The FB pin is an output pin used for DC/DC current mode control error amplifier. In other words, the FB pin detects the

voltages of LED pins (1 to 4) and controls inductor current so that the pin voltage of the LED located in the row with the

highest Vf will come to 0.37V (NADIM=(2.62)V, ILED=100mA). As a result, the pin voltages of other LEDs become higher

by Vf variation. After completion of soft start, the FB pin is put into the high-impedance state with the PWM signal being in

the low state, thus maintaining the FB voltage.

The RT pin is used to connect a DC/DC frequency setting resistor. DC/DC drive frequency is determined by connecting

the RT resistor.

Drive frequency vs. RT resistance (Ideal)

When RT is 100kΩ, Fsw is 150kHz(typ.). However, drive frequency setting should be made in the range of 100 kHz to

800 kHz.

NADIM pin is for analog dimming. Output current is proportionality with input voltage (negative). Basically, NADIM pin

assumes the voltage inputted externally using high accuracy of resistive divider and etc., IC internally is in OPEN (High

impedance) condition.

Please be sure to apply externally for Resistive divider and etc. from REG58 output. Cannot use in an OPEN condition.

The VCC pin is used to supply power for the IC in the range of 9 to 35V.

If the VCC pin voltage reaches 7.5V (Typ.) or more, the IC will initiate operation. If it reaches 7.2V (Typ.) or less, the IC

will be shut down.

]

[

]

[

15000





k

kHz

f

R

SW

RT