Diodes – AH1902 and AH1903: Micropower Hall Switches from Diodes Raise Detection Circuit Performance



Diodes has extended its family of Hall effect switches with the introduction of a pair of high sensitivity, micropower devices. Bringing greater design flexibility and savings in both power and space, the AH1902 and AH1903 help raise the performance bar of a wide range of contact-less switch applications in consumer, domestic, office and industrial products.

The AH1902 is an omnipolar device, detecting both north and south pole magnets. In default mode, the programmable AH1903 operates as a unipolar device, detecting a south pole at the part marked package surface. The device also offers an omnipolar mode, enabling it to meet the needs of multiple applications and to be changed ‘on the fly’ in the event of a field direction issue. The AH1903 function is changed via a simple select pin, driven by an external logic source or microcontroller.

The high sensitivity of both switches means weaker magnets can be employed or detection distances extended; the switches’ typical operating threshold switch point being ±35G.

Designed to be used with a low voltage supply, these latest Hall switches from Diodes will operate over the range 1.6V to 3.6V. This factor, coupled with an integral sleep function and a typical current consumption figure of 4.3µA, make them good performers in battery-powered applications.

To aid product miniaturization, the switches are provided in a choice of space saving low profile surface mount packages. The omnipolar AH1902 comes in the DFN1216-4, ultra thin DFN2015-6 and SOT553 packages. And in the 1.2 x 1.6 x 0.5mm DFN1216-4 package, the AH1903 is the industry’s smallest omnipolar/unipolar programmable Hall switch.

To accommodate a wide range of handheld applications, these high reliability switches have an 8kV electrostatic discharge withstand capability and offer good immunity to RF noise and other circuit stresses. Operating and release points are also highly stable over the temperature range -40ºC to +85ºC, and with a very low temperature coefficient, the switches are immune to early or late switching.


  • Open and close detect for flip/slide cellular phones
  • Smart cover or dock detect for cellular phones, tablet PCs and e-Readers
  • Cover or display switch in portable PCs (e.g. Ultrabook)
  • Digital still, video cameras and handheld gaming consoles
  • Door, lids and tray position switches
  • Level, proximity and position switches
  • Contact-less switches in home appliances and industrial applications


  • Omnipolar operation (north or south pole)
  • Supply voltage of 1.6V to 3.6V
  • High sensitivity
  • Micropower operation
  • Chopper stabilized design provides:
    • Superior temperature stability
    • Minimal switch point drift
    • Enhanced immunity to physical stress
  • No external pull-up resistors required
  • Good RF noise immunity
  • -40°C to +85°C operating temperature
  • High ESD capability of 8kV (human body model)
  • Small low profile X1-DFN1216-4 and X2-DFN2015-6 packages