ALLEGRO micro Systems CT425-50AC Xtreme Sense Isolated Current Sensor
DESCRIPTION
The Allegro MicroSystems CTD425-50AC evaluation board contains the CT425—XtremeSense™ tunnel magnetoresistance (TMR) integrated circuit (IC). This user guide describes the operation and use of the evaluation board as an engineering tool for evaluating the CT425 IC performance in application.
FEATURES
- Integrated current-carrying conductor (CCC)
- Linear analog output voltage
- Total error output ≤ ±1.0% FS
- 1 MHz bandwidth
- Response time: 300 ns
- Low noise: 9 to 13.5 mA rms at fBW = 100 kHz
- Supply voltage: 4.75 to 5.5 V
- Filter function to reduce noise on output pin
- Immunity to common mode fields: –54 dB
EVALUATION BOARD CONTENTS
- CT425-50AC evaluation board
Figure 1: CT425-50AC Evaluation Board
Table 1: CT425-50AC Evaluation Board Configurations
| Configuration Name | Part Number | Sensitivity | Bandwidth |
| CT425-50AC Evaluation Board | CTD425-HSN850MR | 50 mV/V | 1 MHz |
Table 2: General Specifications
| Specification | Min | Nom | Max | Units |
| Input Operating Temperature | –40 | – | 125 | ºC |
| Input Operating Current | –50 | – | 50 | A |
USING THE EVALUATION BOARD
Introduction
The CT425 is a high-bandwidth and ultra-low-noise integrated contact current sensor that uses Allegro-patented XtremeSense™ TMR technology to enable high-accuracy current measurements for many industrial, consumer, and automotive applications. The device supports eight current ranges where the integrated current-carrying conductor (CCC) handles up to 65 A of current and generates a current measurement as a linear analog output voltage. The device achieves a total output error of less than ±1% full-scale (FS).The device has a 300 ns output response time when the current consumption is ~6 mA, and it is immune to common-mode fields. The CT425 has a filter function to reduce the noise on the output pin. The CT425 is offered in an industry-standard 8-lead small-outline integrated circuit (SOIC) package that is green and Restriction of Hazardous Substances (RoHS) compliant.
This section provides an overview of the connections and configuration options of the CT425 evaluation board. The proper configuration is highlighted and detailed in Figure 2. The CT425 datasheet contains detailed information about the use and functionality of each pin and detailed specifications about the sensor. For more detailed information, refer to the product datasheet.
- Figure 2: CT425-50AC Evaluation Board
Power Input
The two large connectors (with screws) are used to connect and drive the external current to be measured. Due to the PCB trace thermal limitation of the CT425 evaluation board, do not exceed 50 APK.
Board Configuration
A fully assembled evaluation board is illustrated in Figure 1 and Figure 2. The current to be measured is connected to the screw connectors located on the right side of the PCB. These connectors are galvanically isolated from the rest of the PCB. The CT425 can be biased by applying a 5 V bias voltage between the VDD and GND pins on the PCB and its output can be measured either from the VOUT SMA connector or the VOUT header pin on the PCB. In addition, if C2 is populated with a 100 pF capacitor, the FILTER SMA connector provides a filtered output of the CT425 with a 3 dB cutoff frequency of approximately 100 kHz; otherwise, the 3 dB cutoff frequency is 1 MHz. Refer to Figure 3.
- Figure 3: CFILTER (pF) vs. 3 dB Cutoff Frequency (kHz)
SCHEMATIC
The schematic of the CT425-50AC evaluation board is shown in Figure 4.
- Figure 4: CT425-50AC Evaluation Board Schematic
LAYOUT
The top and bottom layers of the CT425-50AC evaluation board are shown in Figure 5 and Figure 6, respectively.
- Figure 5: Top Layer
- Figure 6: Bottom Layer
BILL OF MATERIALS
| Designator | Quantity | Description | Manufacturer | Manufacturer Part Number |
| PCB | 1 | CTD425-50AC Evaluation Board | Allegro MicroSystems | – |
| U1 | 1 | CT425 Sensor | Allegro MicroSystems | – |
| J1, J2 | 2 | Screw Connectors | Keystone, Blockmaster | 534-7701 |
| VOUT, FILT | 2 | SMA Connectors | Clinch Connectivity | 142-0701-201 |
| C1 | 1 | 1.0 µF, X5R or Better SMD Capacitor (Bypass Capacitor) 0603 | TDK | CGA3E1X7R1E105K080AC |
| R1, R2 | 2 | 10 kΩ, ±10% or Better SMD Resistor 0603 | Panasonic, AVX, Yageo | ERJ-3GEYJ103V |
| C FILT | 1 | 100 pF, X5R or Better SMD Capacitor 0603 (Optional— See Figure 3) | KEMET | C0603C101K4HACAUTO |
| GND, VDD, P2, P1 | 4 | Male Header Connectors—Single pin | Wurth Elektronik | 732-5334-ND |
| J2 | 1 | M3 Terminal Screw Red | Keystone | 36-7701-2 |
| J1 | 1 | M3 Terminal Screw Black | Keystone | 36-7701-3 |
CT425 product page:
https://www.allegromicro.com/en/products/sense/current-sensor-ics/zero-to-fifty-amp-integrated-conductor-sensor-ics/ct425-6-7-8
For samples or applications support contact, visit https://www.allegromicro.com/en/about-allegro/contact us/technical-assistance and navigate to the appropriate region.
Revision History
| Number | Date | Description |
| – | August 8, 2024 | Initial release |
Copyright 2024, Allegro MicroSystems.
Allegro MicroSystems reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current.
Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use.
Copies of this document are considered uncontrolled documents.
Customer Support
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Documents / Resources
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ALLEGRO micro Systems CT425-50AC Xtreme Sense Isolated Current Sensor [pdf] User Guide CT425-50AC, CTD425-HSN850MR, CT425-50AC Xtreme Sense Isolated Current Sensor, CT425-50AC, Xtreme Sense Isolated Current Sensor, Isolated Current Sensor, Current Sensor, Sensor |
