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AH1894

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

Pin Assignments

(Top View)

X1-DFN1216-4

NEW PRODUCT

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

until B is lower than release point (Brp).

SOT553

(Top View)

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

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

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

DD

, GND

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)

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.

Notes:

Typical Applications Circuit

Note:

4. C

IN

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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AH1894

Pin Descriptions

Package: X1-DFN1216-4

Pin Number

1

2

3

4

Pin Name

OUTPUT

V

DD

BSEL

GND

Function

Output Pin

Power Supply Input

Band Select

Ground Pin

Package: SOT553

NEW PRODUCT

Pin Number

1

2

3

4

5

Note:

Pin Name

V

DD

NC

BSEL

GND

OUTPUT

Power Supply Input

Function

No Connection (Note 5)

Band Select

Ground

Output

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

Functional Block Diagram

AH1894

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AH1894

Absolute Maximum Ratings

(Note 6) (@T

A

= +25°C, unless otherwise specified.)

Symbol

V

DD

V

DD_REV

I

OUTPUT

B

P

D

Ts

T

J

Supply Voltage (Note 7)

Reverse Supply Voltage

Output current (source and sink)

Magnetic Flux Density

Package Power Dissipation

Storage Temperature Range

Maximum Junction Temperature

Human Body Model (HMB) ESD capability

VDD, GND and OUTPUT pins

BSEL pin

X1-DFN1216-4

SOT553

Parameter

Rating

6

-0.3

3.5

Unlimited

230

-65 to +150

150

8

6

mW

°C

kV

Unit

V

mA

NEW PRODUCT

ESD HBM

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

DD

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

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

Recommended Operating Conditions

(@T

A

= +25°C, unless otherwise specified.)

Symbol

V

DD

T

A

Parameter

Supply Voltage

Operating Temperature Range

Operating

Conditions

Rating

1.6V to 3.6V

-40 to +85

Unit

V

°C

Electrical Characteristics

(@T

A

= +25°C, V

DD

= 1.85V, unless otherwise specified.)

Symbol

V

OL

V

OH

Ioff

V

SEL_LB

V

SEL_HB

R

PD_BSEL

I

DD

(awake)

Supply Current

I

DD

(sleep)

I

DD

(avg)

Tawake

Tperiod

D.C.

Notes:

Parameter

Output Low Voltage (on)

Output High Voltage (off)

Output Leakage Current

BSEL pin input voltage – Low Band

BSEL pin input voltage – High Band

BSEL pin internal pull-down resistor

Conditions

I

OUT

= 1mA

I

OUT

= -1mA

V

OUT

= 3.6V, Output off

Min

—

V

DD

-0.2

-

0

1.4

—

Typ

0.1

V

DD

-0.1

<

0.1

—

50

2.1

2.5

4.3

7.2

50

0.1

Max

0.2

—

1

0.5

3.6

—

8

13

100

—

Unit

V

µA

V

kΩ

mA

µA

µs

ms

%

(Note 8)

During ‘awake’ period,

T

A

= +25°C, V

DD

= 3V

During ‘sleep’ period,

T

A

= +25°C, V

DD

= 3V

T

A

= +25°C, V

DD

= 1.85V

T

A

= +25°C, V

DD

= 3.6V

(Note 9)

(Note 10)

Average Supply Current

Awake Time

Period

Duty Cycle

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

9. When power is initially on, the operating V

DD

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

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.

AH1894

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AH1894

Electrical Characteristics

(cont.)

NEW PRODUCT

Magnetic Characteristics

(Note 11 &12) (T

A

= -40°C to +85°C, V

DD

= 1.85V, unless otherwise specified)

BSEL

Low

High

—

Notes:

Symbol

Bops

LB

(South pole to part marking side)

Bopn

LB

(North pole to part marking side)

Brps

LB

(South pole to part marking side)

Brpn

LB

(North pole to part marking side)

Bops

HB

(South pole to part marking side)

Bopn

HB

(North pole to part marking side)

Brps

HB

(South pole to part marking side)

Brpn

HB

(North pole to part marking side)

Bhy (|Bopx|-|Brpx|)

Characteristics

Low Band - Operation Point

Low Band - Release Point

High Band - Operation Point

High Band - Release Point

Hysteresis

Min

15

-45

10

-35

25

-55

20

-45

—

Typ

30

-30

20

-20

40

-40

30

-30

10

(1mT=10 Gauss)

Max

Unit

45

-15

35

-10

55

-25

45

-20

—

Gauss

11. Typical data is at T

A

= +25C, V

DD

= 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 application 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

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July 2013

AH1894

Application Notes

Applications Circuit 1 – Low Band

Leaving the BSEL pin unconnected or connecting the BSEL pin to ground permanently configures the AH1894 into its high sensitivity mode

(lower switching thresholds), requiring a reduced magnetic flux density to activate its output (Low Band).

NEW PRODUCT

Applications Circuit 2 – High Band

Connecting the BSEL pin to V

DD

or applying a voltage greater than 1.4V configures the AH1894 into its low sensitivity mode (higher switching

threshold), requiring a higher magnetic flux density to activate its output (High Band).

Applications Circuit 3 – Adjustable Sensitivity

To enhance the flexibility within the application the sensitivity can be adjusted with a standard logic signal allowing it to be controlled by a micro-

controller or a logic source. This allows the sensitivity to be changed within the application without a hardware change. Whenever the sensitivity

band selection is changed, allow for band selection changeover to complete and output to be valid.

AH1894

Document number: DS35741 Rev. 1 - 2

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July 2013

AH1894

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