Datasheet ACS37002 (Allegro) - 36

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400 kHz, High Accuracy Current Sensor ACS37002 with Pin-Selectable Gains and Adjustable Overcurrent Fast Fault in SOICW-16 Package THERMAL PERFORMANCE Thermal Rise vs. Primary Current
The thermal capacity of the ACS37002 should be verified by the end user in the application’s specific conditions. The maximum Self-heating due to the flow of current should be considered dur- junction temperature, T ing the design of any current sensing system. The sensor, printed J(MAX) (165℃), should not be exceeded. Further information on this application testing is available in circuit board (PCB), and contacts to the PCB will generate heat the DC and Transient Current Capability application note on the as current moves through the system. Allegro website. The thermal response is highly dependent on PCB layout, copper thickness, cooling techniques, and the profile of the injected cur-
Evaluation Board Layout
rent. The current profile includes peak current, current “on-time”, Thermal data shown in Figure 23 and Figure 24 was collected and duty cycle. While the data presented in this section was using the ASEK37002 Evaluation Board (TED-0002825). This collected with direct current (DC), these numbers may be used board includes 750 mm2 of 4 oz. copper (0.1388 mm) connected to approximate thermal response for both AC signals and current to pins 1 through 4, and to pins 5 through 8, with thermal vias pulses. connecting the layers. Top and bottom layers of the PCB are The plot in Figure 23 shows the measured rise in steady-state die shown below in Figure 25. temperature of the ACS37002 versus continuous current at an ambient temperature, TA, of 25 °C. The thermal offset curves may be directly applied to other values of TA. Conversely, Figure 24 shows the maximum continuous current at a given TA. Surges beyond the maximum current listed in Figure 25 are allowed given the maximum junction temperature, TJ(MAX) (165℃), is not exceeded.
Figure 23: Self heating in the MA and LA package due to current flow Figure 25: Top and Bottom Layers for ASEK37002 Evaluation Board
Gerber files for the ASEK37002 evaluation board are available
Figure 24: Maximum Continuous Current
for download from the Allegro website. See the technical docu-
at a Given TA
ments section of the ACS37002 webpage. 36 Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com Document Outline Features and Benefits Description Packages Selection guide Absolute Maximum Ratings Isolation Characteristics MA Package Specific Performance LA Package Specific Performance Pinout Diagram and Terminal List Functional Block Diagram Common Electrical Characteristics Performance Characteristics Functional Description Power-On Reset Operation Power-On Power-Off Power-On Timing Power-On Reset (POR) Overvoltage and Undervoltage Detection Undervoltage Detection Voltage Thresholds (VUVD(H/L)) Overvoltage Detection Voltage Thresholds (VOVD(H/L)) Overvoltage/Undervoltage Detection Hysteresis (VOVDHys, VUVDHys) Overvoltage and Undervoltage Enable and Disable Time (tOVD(E/D), tUVD(E/D)) Supply Zener Clamp Voltages Absolute Maximum Ratings Forward and Reverse Supply Voltage Forward and Reverse Output Voltage Forward and Reverse Reference/Fault Voltage Output Source and Sink Current Definitions of Operating and PErformance Characteristics Zero Current Voltage Output (VIOUT(Q), QVO) QVO Temperature Drift (VQE) Reference Voltage (VREF) Reference Voltage Temperature Drift (VRE) Offset Voltage (VOE) Output Saturation Voltage (VSAT(HIGH/LOW)) Sensitivity (Sens) Sensitivity Error (Esens) Gain Selection Pins Full Scale (FS) Nonlinearity (ELIN) Total Output Error (ETOT) Power Supply Offset Error (VPS) Offset Power Supply Rejection Ratio (PSRRO) Power Supply Sensitivity Error (EPS) Sensitivity Power Supply Rejection Ratio (PSRRS) Fault Behavior Overcurrent Fault (OCF) Overcurrent Fault Operating Range/Point (IOCF-OR, IOCF-OP) Overcurrent Fault Hysteresis (IOCF-Hyst) Voltage Overcurrent Pin (VOC) OverCurrent Fault Error (EOCF) OverCurrent Fault Response Time (tOCF) OverCurrent Fault Reaction Time (tOCF-R) OverCurrent Fault Mask Time (tOCF-MASK) OverCurrent Fault Hold Time (tOCF-HOLD) OverCurrent Fault Persist OCF Disable Dynamic Response Parameters Propagation Time (tpd) Rise Time (tR) Response Time (tRESPONSE) Overshoot Settling Time Temperature Compensation Temperature Compensation Update Rate Application and Theory Application Circuits Theory and Functionality – VOC and OCF VOC Driven by Non-Inverting Buffered VREF Power Supply Decoupling Capacitor and Output Capacitive Loads Dynamically Change Gain in a System Thermal Performance Thermal Rise vs. Primary Current Evaluation Board Layout Package Outline Drawings MA Package LA Package