RGB LED: 11.5V se 12.5V Supply, Resistor Value aur White
Sir ke points:
- Supply 12V fixed nahi, 11.5V se 12.5V (1V ka farq) tak badal sakti hai.
- Resistor value absolute max IF aur datasheet limits ko dekh kar.
- Red, Green, Blue equal-looking brightness, teeno saath on hon to white.
- Agar mumkin ho to ek hi resistor value.
| 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 |
- Ye numbers andaze hain (datasheet mein chromaticity nahi hai).
| 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):
| Case | Red : Green : Blue | Rang |
|---|---|---|
| 12V, typical LED | ~0.55 : 1 : 0.15 | White ke qareeb |
| 12.5V, min Vf LED | ~0.3 : 1 : 0.16 | Greenish/cyan |
| 11.5V, typical LED | Red zyada, G/B kam | Pinkish/orange |
- 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):
- G/B ko 3 series karna (board change)
- Controller se PWM / color calibration
- Constant current driver
- Suggestion (abhi design mein nahi): 12V se 16V boost converter
- 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.