स्टैक साइज़ कैलकुलेटर — सूत्र
## I2C Pull-Up Resistor Sizing
I2C uses open-drain outputs with pull-up resistors. Too small a resistor exceeds sink current; too large slows the rise time.
### Formulas
**R_min = (VCC - V_OL) / I_OL** (current limit)
**R_max = t_rise / (0.8473 x C_bus)** (rise time limit)
The 0.8473 factor comes from the RC time constant to reach 0.7 x VCC.
Choose a standard value between R_min and R_max. Closer to R_min for faster speeds, closer to R_max for lower power.
I2C uses open-drain outputs with pull-up resistors. Too small a resistor exceeds sink current; too large slows the rise time.
### Formulas
**R_min = (VCC - V_OL) / I_OL** (current limit)
**R_max = t_rise / (0.8473 x C_bus)** (rise time limit)
The 0.8473 factor comes from the RC time constant to reach 0.7 x VCC.
Choose a standard value between R_min and R_max. Closer to R_min for faster speeds, closer to R_max for lower power.
हल किया गया उदाहरण
3.3 V supply, standard I2C (3 mA sink, 300 ns rise time), 200 pF bus.
- R_min: (3.3 - 0.4) / 0.003 = 967 ohms
- R_max: 300e-9 / (0.8473 x 200e-12) = 1770 ohms
- Recommended: (967 + 1770) / 2 = 1369 ohms
- Use nearest standard value: 1.2k or 1.5k ohms