GM9130HV Datasheet, PDF (6/9 Pages) Gamma Microelectronics Inc. – 3A LED Driver with Dimming Control

GM9130HV
3A LED Driver with Dimming Control
Application Notes
Output Current (ILED) Design, refer to Figure 1
The current through the LED’s can be set by the formula below.
I_LED = V_FB/R_LOAD
For example, if 2Ω R_LOAD is selected, with V_FB = 200mV typical, then
I_LED = 200 / 2 = 100mA
Power / Heat Consideration
Various I_LED could be obtained by different resistor values as mentioned above. However, taking the
TO263-5 as an example, the maximum power rating must be followed.
T_J = P_IC × θ_JA + T_A
where P_IC is the power of the IC itself, and θ_JA is the thermal resistance (junction to ambient). For
TO263-5, the θ_JA is 50°C/W, the safe power will be
P_{IC =} T_J –T_A /θ_JA = (150 – 25)/50 = 2.5W, and
P_IC = P_IN – P_LED, Where
P_IN = V_IN × I_IN, and
P_LED = V_OUT × I_LED (V_OUT = V_F × number of LED)
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