6/13

Axelite Confidential Materials, do not copy or distribute without written consent.

Rev.1.4 Sep.27, 2019

AX2012



APPLICATION INFORMATION

Setting the ILED Current

Application circuit item shows the basic application circuit with AX2012 adjustable

output version. The external resistor sets the LED output current according to the following

equation:

)

R3

300mV

(

=

I

LED

ILED

R3

20mA

15

Ω

6mW

350mA

0.857Ω

105mW

Over Voltage Protection

OV measure the output voltage for open circuit protection. Connect OV pin to the

output at the top of the LED string. If VOUT above 29V, the OVP protection is happened that

stops the internal driver until VOUT below 29V.

Under Voltage Lockout (UVLO)

To avoid mis-operation of the device at low input voltages an under voltage lockout is

included that disables the device, if the input voltage falls below (2.25V-100mV).

Input Capacitor Selection

The input capacitor reduces the surge current drawn from the input and switching

noise from the device. The input capacitor impedance at the switching frequency shall be

less than input source impedance to prevent high frequency switching current passing to the

input. A low ESR input capacitor sized for maximum RMS current must be used. Ceramic

capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR

and small temperature coefficients. A 4.7µF ceramic capacitor for most applications is

sufficient. For a lower output power requirement application, this value can be decreased.

Output Capacitor Selection

The output capacitor is required to keep the output voltage ripple small and to ensure

regulation loop stability. The output capacitor must have low impedance at the switching

frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their

low ESR and high ripple current. A 1uF ceramic capacitors works for most of the

applications. Higher capacitor values can be used to improve the load transient response.