5140 Datasheet, PDF(4/8 Page) Allegro MicroSystems – PROTECTED POWERHALL SENSOR LAMP/SOLENOID DRIVER

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5140 Datasheet, PDF (4/8 Pages) Allegro MicroSystems – PROTECTED POWERHALL SENSOR LAMP/SOLENOID DRIVER

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5140

PROTECTED POWERHALLÂ®

SENSOR:

LAMP/SOLENOID DRIVER

TYPICAL TRANSFER CHARACTERISTICS

at TA = +25Â°C

VBB

9.0

B OP

6.0

3.0

I OUT= 300 mA

B RP

V OUT(SAT)

100 125 150

MAGNETIC FLUX DENSITY IN GAUSS

175 200

Dwg. GH-007

CIRCUIT DESCRIPTION AND OP-

ERATION

The UGQ5140K merges state-of-the-art

Hall effect sensing and power driving tech-

nologies to allow precision non-contact

actuation of incandescent lamps or inductive

loads. It is rated for operation over an

extended temperature range as typically

required in automotive applications.

MAGNETIC OPERATION

As shown in the Transfer Characteristics

graph, the output of the device (pin 2)

switches low when the magnetic field at the

Hall sensor exceeds the operate point

threshold (BOP). At this point, the output

voltage is VOUT(SAT). When the magnetic field

is reduced to below the release point thresh-

old (BRP), the device output goes high. The

difference in the magnetic operate and

release points is called the hysteresis (BH) of

the part. This built-in hysteresis allows clean

switching of the output even in the presence

of external mechanical vibration and electri-

cal noise.

CURRENT AND THERMAL

LIMITING

Output short circuits may be caused by

faulty connectors, crimped wiring harnesses,

or blown loads. In such cases, current and

thermal limit circuitry will protect the output

transistor against destruction.

Current through the output transistor is

sensed with a low-value on-chip aluminum

resistor. The voltage drop across this

resistor is fed back to control the base drive

of the output stage. This feedback prevents

the output transistor from exceeding its

maximum current density rating by limiting

the output current to approximately 900 mA.

It may also cause the output voltage to

increase (VOUT = VBB - [ILIMIT x RL]). In this

mode, the device will dissipate an increased

amount of power (PD = VOUT x ILIMIT) and the

output transistor will be thermally stressed.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

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