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Current Sensors

Current Sensors
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Bus BarPCB Trace I I > Tot I > Tot I > Sens I > Sens I > Shunt I > Shunt I I > Sens Sens Tot I > Tot

Figure 3. Simulated Current Density for > 1 / > 3 I > Tot Measurement. Data taken at 45 A I > Tot , with 4-oz copper trace. > 5 mm3 mm8.5 mm18 mm3 mm Sense PathI > Tot AB ACS704PCB Trace Shunt PathI > Tot Figure 2. ACS704 PCB Trace Configurations for > 1 / > 3 I > Tot Measurement. The ACS704 is mounted to the PCB trace, in series along the current sense subpath (corresponding to I > PRIMARY through the current sensor). 2 > Worcester, Massachusetts 01615-0036 (508) 853-5000115 Northeast Cutoff, Box 15036 www.allegromicro.comAllegro MicroSystems, Inc. size="-3">

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I > Sens ֏ > c L > Shunt W > Sens R > Primary W Sens T + O > c ( L > Sens1 + L > Sens2 ) > Table 2: Calculated Effect of PCB Trace Weight on Power Dissipation Through Dual Package Divider Trace Weight (oz copper)Power Dissipation at 30 A (W)Overall Resistance(m 5 mm2.2 mm1.7 mmACS704 Packagewith Die ACS704 Packagewithout Die I TotPCB Trace I Tot 8 mm Primary Conduction Path Hall Element Figure 5. Dual Package Solution. Equally divides I Tot using an active and a dummy ACS704 package.Figure 6. Simulated Current Density for Dual Packages. Data taken at 30 A I Tot , with 4-oz copper trace. 4...

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Tot S ACS7xx(B) VCC 40 k R7-120 k > P VOUTGND (TYP)R7-220 k 80 k 2.5 V80 k 40 k V > S 40 k ResultSignal Add Outputs I 80 k (TYP)R820 k ACS7xx(A) VOUTGNDVCC V 80 k I > P 40 k (TYP)40 k 40 k SubtractOffset andAdjust Gain I Invert Signal A > Worcester, Massachusetts 01615-0036 (508) 853-5000115 Northeast Cutoff, Box 15036 www.allegromicro.comAllegro MicroSystems, Inc. size="-1">

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4321I ACS704 (A)ACS704 (B)Combined (V) OUT V 0051015202530 Tot (A) Figure 9. Simulation of Output. Results using ACS704 sen-sors in suggested circuit for combining outputs (figure 8). > Sensor B (red trace) Sensor A (black trace) Output (blue trace) Figure 10. Application of 30 A Pattern to I > Primary in 6 A Incre-ments. The lowest (blue) trace is the output of the interface circuit for combining the two ACS704 outputs. Note that the signals are dc-offset shifted on the oscilloscope, for viewing. 6 > Worcester, Massachusetts 01615-0036 (508) 853-5000115 Northeast Cutoff, Box 15036...

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12 mm7.5 mm13 mm26.5 mm4.3 mm CopperBus Bar Sense PathI I > Tot AB ACS754 > Tot Shunt Path > Tot using an ACS754 sensor in series on a 1-mm-thick copper bus bar.Figure 12. Simulated Current Density for > 1 / > 2 I > Tot Measure-ment. Data taken at 300 A I > Tot , with 4-oz copper trace. Figure 13. Plan and Cross-Section Views of Multilayer Board. This approach, using ACS754 family devices, divides the current according to layer chracteristics, passing a controlled proportion of I > Tot through sensor A. Figure 11. Higher Current Solution. Equally divides I 7 > Worcester, Massachusetts...

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AB CopperBus Bar I > Tot 25 mm25 mm I > Tot Figure 14. Higher Current Solution. Equally divides I > Tot using an ACS754 sensor in series.Figure 15. Simulated Current Density for > 1 / > 2 I > Tot Measure-ment. Data taken at 300 A I > TOT , with 4-oz copper trace. 8 > Worcester, Massachusetts 01615-0036 (508) 853-5000115 Northeast Cutoff, Box 15036 www.allegromicro.comAllegro MicroSystems, Inc. size="-3">

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