Diodes AH1894 User Manual

PROGRAMMABLE HIGH SENSITIVITY

MICROPOWER OMNIPOLAR HALL-EFFECT SWITCH

Description

The AH1894 is a high sensitivity micropower magnetic range selectable Omnipolar Hall effect switch IC with internal pull up and pull down capability. Designed for portable and battery powered equipment such as cellular phones and portable PCs to home appliances and industrial applications, the average power consumption is only 8uW at 1.85V. To support portable equipment the AH1894 can operate over the supply range of 1.6V to 3.6V and uses a hibernating clocking system to minimize the power consumption. To minimize PCB space the AH1894 is available in small low profile X1-DFN1216-4 and SOT553 packages.

The output is activated with either a north or south pole of sufficient magnetic field strength. The user can select one of two magnetic sensitivity bands via the BSEL pin without the addition of any external components allowing a flexible but small solution. The band select can be hardwired or be changed on the fly via a logic source such as a micro-controller. When the magnetic flux density (B) is larger than operate point (Bop), the output will be turned on (pulled low) and held

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until B is lower than release point (Brp).

Features

 Omnipolar Operation (North or South pole)  Programmable Operate and Release Points  Supply Voltage of 1.6V to 3.6V  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) on V

and OUTPUT Pins

 Small Low Profile X1-DFN1216-4 and SOT553 Packages  Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)  Halogen and Antimony Free. “Green” Device (Note 3)

Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.

2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free.

3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds.

, GND

Pin Assignments

(Top View)

X1-DFN1216-4

(Top View)

SOT553

Applications

 Open and Close Detect for Cellular Phones  Holster or cover detect for cellular phones and Tablet PCs  Cover or Display Switches in Portable PCs  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

Typical Applications Circuit

H1894

Note: 4. C

is for power stabilization and to strengthen the noise immunity, the recommended capacitance is 100nF typical.

AH1894

Document number: DS35741 Rev. 1 - 2

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Pin Descriptions

Package: X1-DFN1216-4

Pin Number Pin Name Function

1 OUTPUT Output Pin 2 3 BSEL Band Select 4 GND Ground Pin

Package: SOT553

Pin Number Pin Name Function

1 2 NC No Connection (Note 5) 3 BSEL Band Select 4 GND Ground 5 OUTPUT Output

Note: 5. NC is “No Connection” pin and is not connected internally. This pin can be left open or tied to ground.

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Power Supply Input

Functional Block Diagram

H1894

AH1894

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H1894

Absolute Maximum Ratings (Note 6) (@T

= +25°C, unless otherwise specified.)

Symbol Parameter Rating Unit

VDD

DD_REV

OUTPUT

Supply Voltage (Note 7) 6 V Reverse Supply Voltage -0.3 V Output current (source and sink) 3.5 mA

B Magnetic Flux Density Unlimited

Package Power Dissipation

X1-DFN1216-4 230 mW SOT553 230 mW

Ts Storage Temperature Range -65 to +150 °C

ESD HBM Human Body Model (HMB) ESD capability

Notes: 6. Stresses greater than the 'Absolute Maximum Ratings' specified above may cause permanent damage to the device. These are stress ratings only; functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability may be affected by exposure to absolute maximum rating conditions for extended periods of time.

7. The absolute maximum V operate the device at the absolute maximum rated conditions for any period of time.

Maximum Junction Temperature 150 °C

VDD, GND and OUTPUT pins 8 kV BSEL pin 6 kV

of 6V is a transient stress rating and is not meant as a functional operating condition. It is not recommended to

Recommended Operating Conditions (@T

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= +25°C, unless otherwise specified.)

Symbol Parameter Conditions Rating Unit

VDD

Supply Voltage Operating 1.6V to 3.6V V Operating Temperature Range Operating -40 to +85 °C

Electrical Characteristics (@T

= +25°C, VDD = 1.85V, unless otherwise specified.)

Symbol Parameter Conditions Min Typ Max Unit

VOL Output Lo w Voltage (on) I VOH Output High Voltage (off) I Ioff Output Leakage Current V

BSEL pin input voltage – Low Band 0 — 0.5 V

SEL_LB

BSEL pin input voltage – High Band 1.4 — 3.6 V

SEL_HB

BSEL pin internal pull-down resistor (Note 8) — 50 — kΩ

PD_BSEL

IDD(awake)

Supply Current

IDD(sleep)

IDD(avg)

Average Supply Current

= 1mA — 0.1 0.2 V

OUT

= -1mA V

OUT

= 3.6V, Output off - < 0.1 1 µA

OUT

During ‘awake’ period, T

= +25°C, VDD = 3V

During ‘sleep’ period,

= +25°C, VDD = 3V

= +25°C, VDD = 1.85V

TA = +25°C, VDD = 3.6V

-0.2 V

—

2.1 — mA

—

2.5 — mA

-0.1 — V

— 4.3 8 µA — 7.2 13 µA

Tawake Awake Time (Note 9) — 50 100 µs

Tperiod Period (Note 9) — 50 100 ms

D.C. Duty Cycle (Note 10) — 0.1 — %

Notes: 8. BSEL pin internal pull-down resistor is only active during AWAKE time

AH1894

Document number: DS35741 Rev. 1 - 2

9. When power is initially on, the operating V The output state is valid after the second operating phase (typical 100ms).

10. Transition time varies dependant on the timing of BSEL activation during the sleep and awake phases.

(1.6V to 3.6V) must be applied to guarantee the output sampling.

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Electrical Characteristics (cont.)

H1894

Magnetic Characteristics (Note 11 &12) (T

BSEL Symbol Characteristics Min Typ Max Unit

Low Bops Low BopnLB (North pole to part marking side) -45 -30 -15

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Low BrpsLB (South pole to part marking side)

Low BrpnLB (North pole to part marking side) -35 -20 -10 High Bops High BopnHB (North pole to part marking side) -55 -40 -25 High BrpsHB (South pole to part marking side) High BrpnHB (North pole to part marking side) -45 -30 -20

— Bhy (|Bopx|-|Brpx|) Hysteresis — 10 —

Notes: 11. Typical data is at TA = +25C, VDD = 1.85V.

12. Maximum and minimum parameters values over the operating temperature range are not tested in production, they are guaranteed by design, process control and characterization. The magnetic characteristics may vary with supply voltage, operating temperature and after soldering.

The AH1894 includes a band select pin (BSEL) so that the operate (Bops and Bopn) and release (Brps and Brpn) points can be adjusted between two pre-defined ranges. The BSEL can be hard wired within the application circuit or the band can be selected on the fly by using the BSEL pin as a logic input. This feature allows the AH1894 sensitivity to be changed by firmware within the a pplication without the addition of any external components. If the BSEL pin is left open circuit the AH1894 defaults to low band.

AH1894

Document number: DS35741 Rev. 1 - 2

(South pole to part marking side)

= -40°C to +85°C, VDD = 1.85V, unless otherwise specified)

Low Band - Operation Point

Low Band - Release Point

High Band - Operation Point

High Band - Release Point

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15 30 45

10 20 35

25 40 55

20 30 45

(1mT=10 Gauss)

Gauss

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