RGB LED: 11.5V se 12.5V Supply, Resistor Value aur White

Sir ke points:

Item	Detail
LED	NH-Z2727RGBA-SG (Foshan Nationstar)
Design	4 LEDs series, 1 resistor per string
Supply	11.5V se 12.5V
Use	Outdoor, USA, 70C ambient stress check

Item	Red	Green	Blue
Absolute max current (25C)	25mA	25mA	~20mA (curve)
Max current at 70C (curve, andaze)	~12.4mA	~11.6mA	~9.0mA
Design current (datasheet test current ke qareeb)	12mA	8mA	5mA
Vf min / typ / max	1.8 / 2.1 / 2.5V	2.4 / 2.9 / 3.4V	2.4 / 2.9 / 3.4V
Wavelength (typ)	622nm	530nm	472nm

Vf sirf test current pr diya gaya hai (15 / 8 / 5mA).
Sabse zyada current wala case: 12.5V supply + min Vf. Resistor isi case ke hisab se chuna.

Bacha hua voltage = Supply - (4 x Vf). Minus matlab LED on nahi hogi.

Color	Supply	Min Vf	Typ Vf	Max Vf
Red	11.5V	+4.3V	+3.1V	+1.5V
Red	12.5V	+5.3V	+4.1V	+2.5V
Green/Blue	11.5V	+1.9V	-0.1V	-2.1V
Green/Blue	12.5V	+2.9V	+0.9V	-1.1V

Red pr range ka asar kam hai.
Green/Blue: 11.5V pr typical LED bhi on nahi hoti (4 x 2.9V = 11.6V). 1V ka farq inke liye bohat bara hai.

Color	Resistor	12.5V, min Vf (sabse zyada)	12V, typ Vf	11.5V, typ Vf	11.5V, max Vf
Red	442 ohm	12.0mA	8.1mA	7.0mA	3.4mA
Green	365 ohm	7.9mA	~1.1mA	on nahi	on nahi
Blue	576 ohm	5.0mA	~0.7mA	on nahi	on nahi

Teeno colors 12.5V + min Vf pr bhi absolute max (25mA, Blue ~20mA) aur 70C limit (12.4 / 11.6 / 9mA) ke andar hain.
Typ wale currents fixed Vf se nikale hain. Asli LED mein current kam hone pr Vf girta hai, to G/B kuch mA zyada deti hain. Phir bhi dim hain aur 11.5V pr band ho sakti hain.
Resistor: 1206, 0.25W.

12.5V, min Vf (sabse zyada) / 12V, typ Vf:

Common value	Red	Green	Blue	Verdict
330 ohm	16.1 / 10.9mA	8.8 / 1.2mA	8.8 / 1.2mA	Red 70C limit (12.4mA) se upar, unsafe
442 ohm	12.0 / 8.1mA	6.6 / 0.9mA	6.6 / 0.9mA	Safe, lekin Red ~8mA aur G/B ~1mA, rang red/orange, white nahi

Jawab: ek hi value nahi chalegi. Red ko G/B se alag current chahiye, aur G/B ko 12V pr bohat kam voltage milta hai.

Equal mcd white nahi dega. Aankh Green ko zyada, Blue ko kam dekhti hai, aur teeno ki wavelength alag hai.
Datasheet test currents (15 / 8 / 5mA) pr brightness 450 / 680 / 110 mcd hai. Ye ratio thora pinkish white deta hai.
Neutral white (~5000K) ke liye andaze:

Item	Red	Green	Blue
Current ratio	~11.4mA	~8mA	~3.6mA
Brightness (mcd)	~360	~680	~87
Brightness ratio (G = 1)	~0.5	1	~0.13

Color	Resistor	12.5V min Vf	12V typ (curve se)	11.5V typ
Red	680 ohm	7.8mA	~5 se 6mA	~5mA
Green	301 ohm	9.6mA	~3.9mA	~1 se 2mA
Blue	487 ohm	6.0mA	~2.3mA	~1mA

Brightness ratio (G = 1, andaze):

Red ko jaan boojh kar kam kiya hai (680 ohm), taake dim G/B ke saath balance rahe.
Teeno colors absolute max aur 70C limit ke andar hain.
Rang voltage aur LED ke Vf ke saath badlega, kyunke G/B ka current Vf aur voltage pr bohat depend karta hai.

Sawal	Jawab
Absolute max ke andar safe resistor?	Haan: Red 442, Green 365, Blue 576 ohm (section 3)
Ek hi value teeno ke liye?	Nahi
Fixed resistor se stable white (11.5V se 12.5V)?	Nahi. Sirf approximate white (section 6), rang badlega

Stable white ke liye kuch badalna padega (koi ek):

Sab brightness aur color numbers andaze hain, final prototype pr naapna hoga.
Garmi mein Vf kitna girta hai, datasheet mein nahi, isliye 70C ka guaranteed current nahi nikal sakte.
Dense array mein LED surface 55C se neeche rakhna hai.
Segment aur 9/10 ke LEDs same reel/bin se lo. 9/10 ki values abhi pending hain.