Diodes Incorporated AH1898-CA4-7

Overview

AH1898-CA4-7 from Diodes Incorporated is a programmable micropower omnipolar Hall-effect switch IC with dual magnetic sensitivity bands (Bop/Brp), internal pull-up/pull-down, and hibernating clocking architecture. It operates from 1.6V to 3.6V, draws only 4.3µA typical average supply current at 1.8V, features 8kV HBM ESD rating on VDD/GND/OUTPUT pins, and is housed in a 0.81mm × 0.81mm U-WLB0808-4 (Type A1) CSP package. It enables proximity detection in battery-powered portable electronics such as smartphone flip covers and tablet holsters.

For engineers reviewing the AH1898-CA4-7 datasheet, AH1898-CA4-7 pinout, AH1898-CA4-7 application, or AH1898-CA4-7 equivalent, key selection considerations include its programmable BSEL-driven band switching (low/high sensitivity), chopper-stabilized temperature stability (±0.5G/°C typical drift), ultra-low sleep current (2.5µA), and guaranteed output validity after second awake phase following BSEL transition.

Technical Context

The AH1898 implements a chopper-stabilized Hall plate with offset cancellation and a sleep/awake logic controller that cycles between 100ms periods (50–100ms awake time, >99.9% duty cycle in sleep). Its band-select architecture uses the BSEL pin to configure two discrete magnetic operating windows: low-band Bop = ±18–55G and high-band Bop = ±43–80G, with hysteresis ≥10G in both modes.

Output is open-drain, actively pulled low when |B| exceeds Bop and held until |B| falls below Brp; no external pull-up is required due to integrated pull-down capability. The device maintains stable switching points across –40°C to +85°C and exhibits enhanced immunity to mechanical stress and RF noise via its chopper stabilization and internal filtering.

Key Specifications

Pinout & Package

Package: U-WLB0808-4 (Type A1), 0.81mm × 0.81mm CSP with bottom-side solder balls; moisture sensitivity level 1 per J-STD-020; RoHS-compliant, halogen- and antimony-free "Green" construction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AL33201EUA-7 and TMAG5170AHQDBVR, the AH1898-CA4-7 uniquely delivers firmware-controllable magnetic thresholds in an ultra-low-power switch form factor, enabling one hardware design to support multiple mechanical variants while maintaining µA-level system standby consumption.

Availability

AH1898-CA4-7 is available at Aetrix Electronics and suitable for smartphone cover detection, tablet holster sensing, and portable PC lid switch applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant miniature packaging.

Supply support for AH1898-CA4-7 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability, low-power, and miniaturized solutions for consumer, industrial, and computing markets.

The AH1898 belongs to Diodes' programmable Hall-effect switch product line, engineered specifically for battery-constrained portable electronics where magnetic detection must coexist with multi-year battery life and sub-millimeter PCB real estate constraints.

FAQ

What is the minimum magnetic field strength required to activate the AH1898-CA4-7 in low-band mode?

In low-band mode (BSEL ≤ 0.5V), the typical operate point (Bop) is ±35 Gauss for both north and south poles, with a minimum guaranteed value of ±18 Gauss at 25°C and VDD = 1.8V. At –40°C, Bop shifts by ≤±3G; at +85°C, shift is ≤±5G. Designers should allow ≥20% margin above minimum Bop to ensure robust operation across temperature and mechanical tolerance variations.

Can the BSEL pin be toggled dynamically during normal operation?

Yes - the BSEL pin can be driven by a microcontroller GPIO to switch between low- and high-band sensitivity on-the-fly. However, after each BSEL transition, the output remains invalid for up to 200.1ms (typical 100ms) until the second complete awake phase completes. During this transition window, the output reflects the prior band's state and must not be sampled for system decisions.

Does the AH1898-CA4-7 require an external decoupling capacitor?

Yes - a 100nF ceramic capacitor is recommended between VDD and GND, placed as close as possible to the device's VDD and GND pins. This stabilizes the internal regulator during wake-up events and improves immunity to RF noise and supply transients, especially critical in noisy portable environments with shared power rails.

How does the AH1898-CA4-7 achieve ultra-low average current consumption?

The device uses a hibernating clocking system that places the Hall sensor, amplifier, and logic into deep sleep between sampling intervals. It wakes every 50–100ms for ~100µs to sample magnetic field and update output, resulting in 99.9% sleep duty cycle. Combined with optimized analog front-end biasing, this achieves 4.3µA average current at 1.8V - verified across full temperature and voltage range.