Datasheet MAX4073T, MAX4073F, MAX4073H (Maxim) - 8
| Hersteller | Maxim |
| Beschreibung | Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier |
| Seiten / Seite | 12 / 8 — MAX4073T/F/H. Low-Cost, SC70, Voltage-Output, High-Side Current-Sense … |
| Revision | 1 |
| Dateiformat / Größe | PDF / 370 Kb |
| Dokumentensprache | Englisch |
MAX4073T/F/H. Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier. Using a PCB Trace as RSENSE
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MAX4073T/F/H Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier
somewhat better, and low-inductance metal-film resis- tors are best suited for these applications. INPUT LOAD/BATTERY RSENSE For VSENSE = 100mV, full-scale output voltage can be 0.3in COPPER 0.1in COPPER 0.3in COPPER _ 2V, 5V, or 10V depending on the gain. For proper oper- + VSENSE ation, ensure VCC exceeds the full-scale output voltage by 1.2V (see Output High Voltage (VCC - VOH) vs. RS+ RS- +3V TO +28V Temperature in the Typical Operating Characteristics). VCC 0.1µF
Using a PCB Trace as RSENSE
MAX4073T If the cost of RSENSE is an issue and accuracy is not critical, use the alternative solution shown in Figure 2. OUT This solution uses copper PC board traces to create a sense resistor. The resistivity of a 0.1-inch-wide trace of GND 2-ounce copper is approximately 30mΩ/ft. The resis- tance-temperature coefficient of copper is fairly high (approximately 0.4%/°C), so systems that experience a Figure 2. MAX4073T Connections Showing Use of PC Board wide temperature variance must compensate for this effect. In addition, do not exceed the maximum power dissipation of the copper trace. For example, the MAX4073T (with a maximum load cur- rent of 10A and an RSENSE of 5mΩ) creates a full-scale ILOAD VSENSE VIN LOW-COST +2V TO +28V VSENSE of 50mV that yields a maximum VOUT of 1V. SWITCHING RSENSE in this case requires about 2 inches of 0.1 inch- REGULATOR RSENSE wide copper trace. +3V TO +28V RS+ RS-
Output Impedance
VCC 0.1µF The output of the MAX4073 is a current source driving a MAX4073T/F/H 12kΩ resistance. Resistive loading added to OUT reduces the output gain of the MAX4073. To minimize output errors for most applications, connect OUT to a LOAD/ OUT BATTERY high-impedance input stage. When output buffering is GND required, choose an op amp with a common-mode input range and an output voltage swing that includes ground when operating with a single supply. The op amp’s supply voltage range should be at least as high Figure 3. Current Source as any voltage the system may encounter. The percent error introduced by output loading is deter- mined with the following formula: ⎛ R ⎞ % = 100 LOAD − 1 ERROR ⎜ ⎟ ⎝ 12k Ω + RLOAD ⎠ where RLOAD is the external load applied to OUT.
Current Source Circuit
Figure 3 shows a block diagram using the MAX4073 with a switching regulator to make a current source.
8
Maxim Integrated
somewhat better, and low-inductance metal-film resis- tors are best suited for these applications. INPUT LOAD/BATTERY RSENSE For VSENSE = 100mV, full-scale output voltage can be 0.3in COPPER 0.1in COPPER 0.3in COPPER _ 2V, 5V, or 10V depending on the gain. For proper oper- + VSENSE ation, ensure VCC exceeds the full-scale output voltage by 1.2V (see Output High Voltage (VCC - VOH) vs. RS+ RS- +3V TO +28V Temperature in the Typical Operating Characteristics). VCC 0.1µF
Using a PCB Trace as RSENSE
MAX4073T If the cost of RSENSE is an issue and accuracy is not critical, use the alternative solution shown in Figure 2. OUT This solution uses copper PC board traces to create a sense resistor. The resistivity of a 0.1-inch-wide trace of GND 2-ounce copper is approximately 30mΩ/ft. The resis- tance-temperature coefficient of copper is fairly high (approximately 0.4%/°C), so systems that experience a Figure 2. MAX4073T Connections Showing Use of PC Board wide temperature variance must compensate for this effect. In addition, do not exceed the maximum power dissipation of the copper trace. For example, the MAX4073T (with a maximum load cur- rent of 10A and an RSENSE of 5mΩ) creates a full-scale ILOAD VSENSE VIN LOW-COST +2V TO +28V VSENSE of 50mV that yields a maximum VOUT of 1V. SWITCHING RSENSE in this case requires about 2 inches of 0.1 inch- REGULATOR RSENSE wide copper trace. +3V TO +28V RS+ RS-
Output Impedance
VCC 0.1µF The output of the MAX4073 is a current source driving a MAX4073T/F/H 12kΩ resistance. Resistive loading added to OUT reduces the output gain of the MAX4073. To minimize output errors for most applications, connect OUT to a LOAD/ OUT BATTERY high-impedance input stage. When output buffering is GND required, choose an op amp with a common-mode input range and an output voltage swing that includes ground when operating with a single supply. The op amp’s supply voltage range should be at least as high Figure 3. Current Source as any voltage the system may encounter. The percent error introduced by output loading is deter- mined with the following formula: ⎛ R ⎞ % = 100 LOAD − 1 ERROR ⎜ ⎟ ⎝ 12k Ω + RLOAD ⎠ where RLOAD is the external load applied to OUT.
Current Source Circuit
Figure 3 shows a block diagram using the MAX4073 with a switching regulator to make a current source.
8
Maxim Integrated