SS351AT Omnipolar Digital Hall-Effect Sensor IC Datasheet Summary

1. General Overview

The SS351AT is a compact, versatile omnipolar digital Hall-effect sensor IC manufactured by Honeywell Sensing and Productivity Solutions. Designed to respond to both North and South magnetic poles, it eliminates the need for magnet polarity identification during installation, simplifying integration and reducing system costs. With a typical operating point of 85 Gauss at 25°C, the sensor offers high sensitivity and reliability across a wide temperature range, making it suitable for commercial, industrial, and medical applications. It is packaged in a subminiature SOT-23 surface-mount form factor, supplied on tape and reel for automated component placement, enabling compact PCB designs. The device complies with RoHS Directive 2002/95/EC and features built-in reverse polarity protection for enhanced durability.

2. Key Specifications

2.1 Electrical Characteristics (Vs = 3.0–24.0 Vdc, 20 mA load, TA = -40°C to 150°C unless otherwise specified)

表格

2.2 Magnetic Characteristics (TA = 25°C)

表格

2.3 Absolute Maximum Ratings

表格

3. Package & Mechanical Details

3.1 Package Specifications

• Package Type: SOT-23 (subminiature surface-mount)
• Packaging: Tape and reel (3000 units per reel)
• Pin Configuration (Top View):
• Key Dimensions (mm/[in]):
• Soldering Conditions: Infrared reflow process – peak temperature 245°C [473°F] for maximum 10 seconds.

3.2 Reel & Tape Dimensions (For Automated Assembly)

• Reel Outer Diameter: 178 mm [7.01 in] max.
• Reel Arbor Hole Diameter: 20.2 mm [0.795 in] min.
• Tape Width: 8.0 mm [0.314 in]
• Tape Thickness: 0.20 mm [0.008 in]
• Tape Start Slot: 4.00 mm [0.157 in] width, depth >10 mm [0.394 in]

4. Functional Features

4.1 Core Capabilities

• Omnipolar Operation: Activates with either North or South magnetic pole, simplifying installation and magnet orientation.
• Low Voltage Compatibility: Operates from 3.0 Vdc to 24.0 Vdc, compatible with low-voltage systems and industrial power supplies.
• Fast Switching Speed: 1.5 μs rise/fall time enables high-speed sensing applications (e.g., RPM measurement).
• Thermally Balanced Design: Maintains stable performance across the full operating temperature range (-40°C to 150°C).
• Reverse Polarity Protection: Built-in circuitry prevents damage from incorrect power supply wiring.
• Current Sinking Output: Configurable for direct connection to loads, transistors, or logic gates (see Figure 2 for block diagram).

4.2 Output Behavior

• The sensor’s output toggles between ON and OFF states based on magnetic field strength relative to Bop (operate) and Brp (release) points.
• If powered up with a magnetic field in the differential zone (Brp < field < Bop), the initial output may be either ON or OFF. Honeywell recommends a 10 μs stabilization delay after Vs reaches 5 Vdc before reading the output.
• Magnetic switch points (Bop/Brp) exhibit minimal temperature drift, ensuring consistent performance in harsh environments (see Figure 1 for temperature vs. magnetic performance curve).

5. Application Information

5.1 Target Applications

Commercial

• Speed/RPM sensing in fitness equipment
• Magnetic encoders for building access control
• Damper/valve position control in HVAC systems
• Flow-rate sensing in appliances and water softeners
• Printer head position detection

Industrial

• Flow meters
• Robotic cylinder position monitoring
• Float-based fluid level sensing
• Motion control and proximity sensing
• Instrumentation and metering

Medical

• Position sensing in hospital beds and medical equipment
• Medication bin monitoring on portable drug carts

5.2 Recommended Wiring Configurations

The SS351AT supports multiple wiring schemes for flexibility in system integration (see Figure 4 for detailed diagrams):

• Direct connection to TTL/DTL gates (with current-limiting resistor)
• LED drive circuits (50 mA max load)
• Relay control via PNP/NPN transistors (supports up to 150 mA load)
• AC load control with TRIAC/SCR (external driver required)
• Typical pull-up resistor values: 10 kΩ–47 kΩ (depending on supply voltage and load type)

6. Ordering & Compliance

• Part Number: SS351AT
• Ordering Information: SOT-23 package, tape and reel (3000 units per reel)
• Compliance: RoHS Directive 2002/95/EC (Pb-free, halogen-free)
• ESD Sensitivity: Class 2 – handle only at static-free workstations
• Product Family: Part of Honeywell’s Omnipolar Digital Hall-effect Sensor lineup (includes SS451A, SS551AT, SL353HT, SL353LT)