YB1303 Datasheet, PDF (5/8 Pages) YOBON TECHNOLOGIES,INC. – Low Dropout LED Driver

YB1303
Low Dropout LED Driver
Application Information
Analog Dimming Control Table
voltage. The lower the V_LED voltage, the
higher the system efficiency. The system
Table 4
V_EN=3V, V_CONTROL=3V
I_LED (mA)
R_SET (kΩ)
5
75
10
34
15
24
20
17.4
25
13
efficiency can be calculated as follows:
Efficiency = (V_IN-V_CATHODE) / V_IN
Thermal Considerations
At any given ambient temperature, the
maximum package power dissipation can
be determined by the following equation:
Table 5
V_EN=3V, R_SET=17.4k
I_LED (mA) V_CONTROL (V)
5
1.5
10
2.1
15
2.5
20
3
25
3.6
P_D(MAX) = [T_J(MAX)-T_A] / θ_JA
Constraints for the YB1303 are maximum
junction temperature T_J(MAX)=125 ℃ , and
package thermal resistance, θ_JA=300℃/W.
The maximum total LED current for
YB1303 depends on package power
Setting the LED Current
The LED current can be set by the control
voltage and the R_SET resistor from the
following equation.
I_LED=200×(V_CONTROL-V_CTR)/R_SET
dissipation and the LED cathode voltage at
T_J(MAX). At 85℃, P_D(MAX)=133mW. At T_A =
25℃, P_D(MAX)=333mW.
The maximum current is calculated by the
following equation:
I_LED < (P_D(MAX) / V_LED(MAX))
The suggested values and relations
between V_CONTROL and R_SET can also be
found in the diagram of typical
characteristics and table 4 and table5. The
LED brightness can be controlled by either
the above equation or applying a PWM
signal to the EN pin. The driving signal
For example, if I_LED = 60mA, and T_A = 85℃,
V_LED(MAX) = 2.2V.
If the ambient temperature were to
increase, the internal die temperature
would increase, and the device would be
damaged.
frequency should be greater than 100Hz to
avoid flickering, and increased to more
than 1MHz if necessary.
Efficiency Considerations
Application Examples
The ultra-low voltage drop across the
YB1303 allows the devices to drive white,
blue and any color LEDs in a wide range of
The YB1303 featured low drop out can input voltages. The driver can be used in
achieve excellent efficiency performance. many applications presented in this
The efficiency is mainly dominated by V_LED document, due to their similar operation.
YB1303 Rev.1.0
www.yobon.com.tw
5