高侧电流检测的测量：集成电路和原则-High-Side

• Voltage Loss: High RSENSE values cause the power-source voltage to degrade through IR loss. The lowest RSENSE value gives the least voltage loss.
• Accuracy: High RSENSE values let you measure low-level currents more accurately, because the voltage offset and input bias-current offsets are less significant with respect to the sense voltage.
• Efficiency and Power Dissipation: At high current levels, the I2R loss in RSENSE can be substantial, so take that into consideration when choosing the resistor value and power-dissipation rating (wattage). Excessive heat in the sense resistor can also cause its value to drift.
• Inductance: If ISENSE has a large high-frequency component, RSENSE must have low inductance. Wire-wound resistors have the highest inductance. Metal-film resistors are somewhat better, but low-inductance metal-film resistors (available in values under 1 1/2 Ω) are recommended. Unlike the metal-film and wire-wound types (spiral-wrapped around a core), low-inductance metal-film resistors consist of a straight band of metal.
• Cost: Using a PC-board trace as a sense resistor (Figure 10) is an alternative method for applications where the cost of RSENSE is an issue. You will need to adjust the full-scale current value with a potentiometer because of inaccuracy in the copper resistance. The resistance temperature coefficient of copper is fairly high (approximately 0.4%/°C) in systems that undergo wide temperature variations.

High-Side-Monitor Applications