4.7 kΩ and 750 Ω
- Input
- 24V 4.7k 750
- Expected output
- 3.30V
+0.08%, 4.4 mA, R1 at 91 mW.
Carregando ferramenta… / Loading tool…
24v to 3.3v voltage divider
Industrial 24 V panels and 3.3 V analog inputs meet in sensor and battery voltage readings. The divider is the simplest way to scale down, and with a ratio above six to one, the choice of resistor size matters as much as the ratio. The tool opens with 24 V and 3.3 V, listing the E24 pairs with error, current and grouped by total resistance.
+0.08%, 4.4 mA, R1 at 91 mW.
0.44 mA and 10.6 mW in total.
−0.09%, but 7.7 mA and 184 mW.
5% below target.
+1.3%, 3.04 mA.
The load pulls the output down by 6%.
Vout = Vin × R2 ÷ (R1 + R2), with R1 between the input and the output and R2 between the output and ground. For 5 V with R1 = 1 kΩ and R2 = 2 kΩ, Vout = 5 × 2000 ÷ 3000 = 3.33 V.
R1 ÷ R2 should be 6.27. In E24, 4.7 kΩ and 750 Ω give 3.303 V. To draw less current use 47 kΩ and 7.5 kΩ, with the same ratio and 0.44 mA.
With 4.7 kΩ and 750 Ω at 24 V, R1 dissipates about 91 mW, which fits in a 1/4 W resistor with a small margin. With 47 kΩ and 7.5 kΩ it is 9 mW. The tool shows each resistor's power.
It works for measurement, as long as the converter accepts the impedance and the circuit has surge protection. The voltage can rise well above the resting value; size it for the maximum expected.
Because the 6.27 ratio requires specific values and E12 has few per decade. The best E12 pair sits about 5% below 3.3 V. E24 gets within tenths of a percentage point.
R1 + R2 between 100 Ω and 1 kΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 750 Ω | 120 Ω | 3.31 V | +0.31% | 27.6 mA | |
| 820 Ω | 130 Ω | 3.284 V | −0.48% | 25.3 mA | |
| 620 Ω | 100 Ω | 3.333 V | +1.01% | 33.3 mA |
R1 + R2 between 1 kΩ and 10 kΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 4.7 kΩ | 750 Ω | 3.303 V | +0.08% | 4.4 mA | |
| 2.7 kΩ | 430 Ω | 3.297 V | −0.09% | 7.67 mA | |
| 3.9 kΩ | 620 Ω | 3.292 V | −0.24% | 5.31 mA |
R1 + R2 between 10 kΩ and 100 kΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 47 kΩ | 7.5 kΩ | 3.303 V | +0.08% | 440 µA | |
| 27 kΩ | 4.3 kΩ | 3.297 V | −0.09% | 767 µA | |
| 39 kΩ | 6.2 kΩ | 3.292 V | −0.24% | 531 µA |
R1 + R2 between 100 kΩ and 1 MΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 470 kΩ | 75 kΩ | 3.303 V | +0.08% | 44 µA | |
| 270 kΩ | 43 kΩ | 3.297 V | −0.09% | 76.7 µA | |
| 390 kΩ | 62 kΩ | 3.292 V | −0.24% | 53.1 µA |
R1 + R2 between 1 MΩ and 10 MΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 1 MΩ | 160 kΩ | 3.31 V | +0.31% | 20.7 µA | |
| 910 kΩ | 150 kΩ | 3.396 V | +2.92% | 22.6 µA | |
| 1 MΩ | 150 kΩ | 3.13 V | −5.14% | 20.9 µA |
One group per range of total resistance. A low sum wastes current, a high sum lets the load pull the output down. The error is only series rounding; add the resistor tolerance on top.
The math runs in your browser; no value is sent to a server. A resistive divider is for signals and references, not for powering circuits that draw current.