CQ330B Hall Effect Current Sensor - Equivalent & Substitute Parts

Part Overview

The CQ330B is a Hall Effect open-loop current sensor manufactured by Asahi Kasei Microdevices (AKM) designed for AC/DC current measurement applications. It features a 21A sensing range with ratiometric voltage output and bidirectional polarization capability. The device is classified as obsolete, making identification of suitable substitute components essential for ongoing system support and new design implementations. The CQ330B operates from a 4.5V to 5.5V supply and is housed in a 24-LSSOP surface mount package.

Substiute Parts

CQ330B

Asahi Kasei Microdevices/AKMIn Stock: 1183CQ330B Datasheet

Current PartRFQ

CZ3721

Asahi Kasei Microdevices/AKMIn Stock: 1812CZ3721 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The CQ330B can be substituted with the CZ3721 based on the following critical parameters that define functional equivalence:

Substitution Criteria:

• Manufacturer: Both parts are manufactured by Asahi Kasei Microdevices (AKM), ensuring design and quality consistency
• Sensor Technology: Both utilize Hall Effect open-loop architecture for current measurement
• Output Configuration: Both provide ratiometric voltage output suitable for direct microcontroller integration
• Supply Voltage: Identical 4.5V to 5.5V operating range ensures drop-in compatibility with existing power supplies
• Single Channel: Both devices feature one measurement channel
• Surface Mount Technology: Both are surface mount components compatible with standard PCB assembly processes
• Current Sensing Range: CZ3721 (20.6A) is within acceptable tolerance of CQ330B (21A) for most applications
• Compliance: Both meet RoHS requirements for environmental and regulatory compliance

The primary design difference is the package format transition from 24-LSSOP to 16-PowerSOIC, which requires PCB layout modification but maintains electrical compatibility.

Parameter Comparison

Engineering Selection Recommendations

CZ3721 as Primary Substitute:

The CZ3721 is the manufacturer-recommended substitute for the obsolete CQ330B. Selection of this part is justified by:

• Active product status ensures long-term availability and manufacturing support
• Identical supply voltage range (4.5V ~ 5.5V) eliminates power supply modifications
• Equivalent Hall Effect open-loop architecture maintains measurement principle consistency
• RoHS compliance status meets current regulatory requirements
• Extended operating temperature range (-40°C ~ 105°C) provides broader environmental capability compared to the CQ330B (-40°C ~ 90°C)

Design Considerations:

The CZ3721 introduces three functional differences that require evaluation:

1. Polarization Change: CZ3721 is unidirectional versus CQ330B bidirectional. Applications requiring bidirectional current measurement must implement external signal conditioning or select alternative parts.

2. Package Transition: Migration from 24-LSSOP to 16-PowerSOIC requires PCB footprint redesign. The 16-PowerSOIC package is wider (7.70mm vs 5.60mm), necessitating layout modifications.

3. Performance Trade-offs: CZ3721 exhibits slower response time (1µs vs 0.5µs) and higher supply current draw (25mA vs 11mA), which may impact power budget and high-frequency measurement applications.

For applications where bidirectional measurement is mandatory, alternative substitutes from the AKM product line should be evaluated.

Frequently Asked Questions (FAQ)

Q: Can the CZ3721 directly replace the CQ330B without PCB modifications?

A: No. The CZ3721 uses a 16-PowerSOIC package while the CQ330B uses a 24-LSSOP package. Different footprints require PCB layout redesign. However, the electrical interface and pin configuration are compatible after layout adjustment.

Q: What is the impact of the unidirectional polarization in the CZ3721?

A: The CQ330B measures current in both directions (bidirectional), while the CZ3721 measures current in one direction only (unidirectional). Applications requiring bidirectional current sensing must either implement external signal conditioning or select an alternative part that maintains bidirectional capability.

Q: Are there compatibility issues with the sensitivity difference between CQ330B (196mV/A) and CZ3721 (200mV/A)?

A: The 4mV/A difference (approximately 2%) is within typical calibration tolerances for ratiometric voltage output sensors. Firmware calibration adjustments can accommodate this variance. Both parts provide ratiometric output, allowing software-based compensation.

Q: Does the CZ3721 operate at the same supply voltage as the CQ330B?

A: Yes. Both parts operate from 4.5V to 5.5V, eliminating the need for power supply modifications during substitution.

Q: What is the significance of the accuracy difference (CQ330B ±0.5% vs CZ3721 ±1.7%)?

A: The CQ330B provides tighter accuracy specification. Applications with strict measurement accuracy requirements should evaluate whether the CZ3721's ±1.7% accuracy meets system specifications. For general-purpose current sensing, this difference is typically acceptable.

Q: How does the response time difference affect system performance?

A: The CQ330B responds in 0.5µs while the CZ3721 responds in 1µs. For applications operating below 500kHz, this difference is negligible. High-frequency current measurement or fast transient detection may require the faster CQ330B response time.

Q: Is the CZ3721 suitable for high-temperature applications?

A: The CZ3721 operates to 105°C, exceeding the CQ330B's 90°C maximum. For applications requiring extended temperature operation above 90°C, the CZ3721 provides improved thermal capability.

Q: What is the impact of increased supply current (CZ3721 25mA vs CQ330B 11mA)?

A: The CZ3721 draws 14mA additional supply current. For battery-powered or power-constrained applications, this increased draw should be evaluated against system power budgets.