• 1.

    Operating Temp. Range: The combination of ambient temperature and temperature rise.

  • 2.

    Secondary Inductance: Tested @ 17.5KHz, 1VRMS, Series. CT03-1000-A is tested @ 1KHz, 1VRMS, Series.

  • 3.

    Current Rating: The primary current rating is for reference only and is limited by the current capacity of the customer-supplied primary conductor.

  • 4.

    SRF: Values are for reference only.

  • 5.

    Flammability Standard: Meets UL 94V-0.

  • 6.

    Terminating Resistor (RB): To calculate the value use the formula,
    RB = EOTR/IP

  • 7.

    ET Product: The maximum ET is based upon a flux density of 3700 Gauss at 25°C. Suitable for bipolar applications only.

    ET = EO/2f
    EO = IPRB/TR

    Where as,

    EO = Output voltage (V)   TR = Turns Ratio
    RB = Term. Resistor (Ω)       f = Frequency (Hz)
    IP = Primary Current (A)

     

    P/N Designator Suffix:
    C – Center Tapped Secondary
    N – Non-Center Tapped Secondary

  • 8.

    PACKAGING

    • Pieces/Tray: 270

    • Trays/Box: 5

    • Pieces/Box: 1350

  • 9.

    Compliance & Solutions:

    RoHS Compliant    Custom Solutions

  • 10.

    Specifications subject to change without prior notice.

Frequently Asked Questions (FAQs)

How do I choose the correct turns ratio for CT03?

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Selecting the turns ratio depends on the sense-voltage required at the controller or sensing circuit, the expected primary current range, and the burden resistor value. Lower ratios (e.g. 1:50) yield smaller sense voltages, suitable for high-current applications with modest sense-voltage demands; higher ratios (e.g. 1:200, 1:1000) allow lower primary currents to generate a usable sense signal. Ensure the burden resistor value and waveform remain within the ET-product and voltage limits specified in the datasheet when making the selection.

What burden resistor should be used with CT03?

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A burden resistor should be selected so that the output sense voltage matches the input range of the controller or measurement circuit while staying within transformer limits. Use the datasheet formula (Rb = Eo·TR / Ip) to calculate burden resistance based on your target output voltage, turns ratio, and primary current. Correct sizing ensures accurate sensing while preventing core saturation or excessive heating.

Can CT03 be used for current-mode SMPS controllers or protection circuits?

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Yes. CT03 is suitable for current-mode control, over-current detection, load-drop monitoring, and other protection or feedback functions in AC/DC and DC/DC converters. Its encapsulated design, wide isolation rating, and flexible turns ratios make it applicable in designs where reliable, isolated current sensing is required for mid-to-high current rails.

Does CT03 require special PCB layout practices?

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Because CT03 is a through-hole transformer, the primary path is normally a PCB trace or wire routed directly through the device terminals. For best performance, keep secondary traces short, place the burden resistor close to the transformer pins, and avoid routing high-noise switching nodes near the sense path to maintain clean waveform fidelity.

Is CT03 suitable for pulsed or non-sinusoidal switch-mode currents?

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Yes, CT03 is designed for switch-mode power environments and can measure pulsed inductor currents or other non-sinusoidal waveforms. Designers must ensure that the applied volt-seconds stay within the ET-product limits for the selected part number so that the transformer does not saturate under high-duty or high-amplitude conditions.

How much isolation does CT03 provide, and is it suitable for safety-critical designs?

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CT03 provides 3750 VAC isolation and maintains creepage and clearance distances consistent with UL and EN power supply standards. Its encapsulated construction allows it to be used in applications where safe separation between high-current primary paths and sensitive secondary circuitry is required.

What factors influence CT03’s accuracy at higher switching frequencies?

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Accuracy is affected by leakage inductance, secondary parasitics, the burden resistor value, and PCB layout. Since CT03 operates below the higher frequencies supported by SMT models like CT01 or CT02, maintaining appropriate burden values and minimizing parasitic capacitances is essential for clean current reproduction near its upper operating range.

How should CT03 be installed in the measured current path?

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The conductor carrying the current to be sensed is routed through the transformer’s primary pins, while the secondary winding and burden resistor generate a scaled output voltage proportional to that current. This configuration enables CT03 to be used for inductor-leg monitoring, rail sensing, or protection functions across a variety of power stages.

Can CT03 be used for both AC and DC-linked current measurements?

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Yes, as long as the measurement is effectively AC-coupled. CT03 cannot measure static DC, but it accurately measures AC or pulsed DC waveforms typical of switching supplies. Proper burden selection and waveform filtering help maintain signal accuracy for these non-sinusoidal operating conditions.

Where can I find technical documentation, models, and mechanical drawings for CT03?

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The CT03 product page provides the datasheet, mechanical outlines, layout guidelines, and options to request SPICE or 3D CAD models. These resources make it straightforward to integrate CT03 into simulation workflows and PCB designs.