Diodes Incorporated AH277AZ4-AG1

Overview

AH277AZ4-AG1 from BCD Semiconductor Manufacturing Limited is a complementary-output Hall-effect latch IC designed for electronic commutation in brushless DC motors. It integrates a Hall sensor, amplifier, Schmitt trigger with hysteresis, temperature compensation, band-gap regulator, and dual open-collector drivers-supporting 3.5–16 V supply, ±50 G operating point (Grade A), and 400 mA average sink current per output in TO-94 (SIP-4L) package.

For engineers reviewing the AH277AZ4-AG1 datasheet, AH277AZ4-AG1 pinout, AH277AZ4-AG1 application, or AH277AZ4-AG1 equivalent, key selection considerations include magnetic switching thresholds (BOP/BRP), complementary output timing symmetry, reverse supply protection, thermal derating at 85°C ambient, and compatibility with dual-coil motor phase sequencing.

Technical Context

The AH277AZ4-AG1 implements a bipolar latching Hall sensor architecture with built-in hysteresis (60 G typical) to reject noise during magnetic transitions. Its dual open-collector outputs (DO and DOB) provide complementary logic states-DO low / DOB high when B ≥ +30 G, and DO high / DOB low when B ≤ −30 G-enabling direct drive of external pull-up loads in motor phase control.

Internal temperature compensation maintains stable BOP/BRP across −20°C to +85°C, while the band-gap regulator ensures consistent biasing of analog blocks. The device features reversed supply voltage protection (−20 V absolute max), ESD robustness (300 V MM), and operates with 12–16 mA supply current at full VCC.

Key Specifications

Pinout & Package

Package: TO-94 (SIP-4L), 4-pin single-inline package with 2.54 mm pitch, low-profile construction (max height 5.28 mm), lead-free and RoHS-compliant (G1 suffix).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Hall-effect latch applications.

Compared with A3291LUA-T and US5881KSE-ABA-000-RE, AH277AZ4-AG1 uniquely delivers matched complementary open-collector outputs with tight magnetic hysteresis and reverse-supply tolerance-making it optimal for cost-sensitive, space-constrained BLDC fan and motor commutation where external logic inversion is undesirable.

Availability

AH277AZ4-AG1 is available at Aetrix Electronics and suitable for brushless DC motor commutation, dual-coil fan control, revolution counting, and speed measurement requiring stable component supply across industrial temperature ranges and long-lifecycle production programs.

Supply support for AH277AZ4-AG1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

BCD Semiconductor Manufacturing Limited is a Shanghai-based analog and mixed-signal IC designer specializing in power management, motor control, and sensor interface solutions for industrial and consumer applications.

The AH277A product line targets cost-effective, robust Hall-effect sensing for brushless motor commutation-emphasizing integration, thermal stability, and package compatibility with high-volume motor module assembly.

FAQ

What is the magnetic hysteresis value of AH277AZ4-AG1, and how does it affect noise immunity?

The AH277AZ4-AG1 has a typical magnetic hysteresis (BHYS) of 60 Gauss, defined as the difference between operate point (BOP) and release point (BRP). This hysteresis prevents false triggering during slow or noisy magnetic field transitions-such as those caused by mechanical vibration or EMI near motor windings-ensuring clean, bounce-free output edges critical for reliable commutation timing.

Can AH277AZ4-AG1 drive MOSFET gates directly without external buffers?

AH277AZ4-AG1's 400 mA average sink current and 0.35 V saturation voltage at 400 mA allow direct drive of small-signal MOSFET gates (e.g., 2N7002-level) with 10 kΩ pull-up resistors. However, for power MOSFETs requiring >1 nC gate charge, an external buffer stage is recommended to ensure sub-microsecond turn-on and prevent shoot-through in half-bridge configurations.

Does AH277AZ4-AG1 require external decoupling capacitors, and what values are recommended?

Yes-per the datasheet's Figure 13, a 2.2 µF ceramic capacitor between VCC and GND is recommended adjacent to the device. This stabilizes the internal band-gap regulator under dynamic load transients and suppresses supply ripple induced by switching motor coils. Additional 0.1 µF local bypass is advised if routing inductance exceeds 5 nH.

How does the reversed supply voltage protection work, and what are its limitations?

AH277AZ4-AG1 incorporates an internal series diode that blocks reverse current flow into VCC, protecting the chip up to −20 V. However, this protection applies only on the IC side-not the motor coil side. As noted in datasheet Note 2, an external blocking diode (e.g., 1N4007) must be added in series with the coil supply to prevent reverse current from damaging external components during polarity reversal testing.