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Elmos: Stepper Motor Driver for Automatic Headlight Adjustment

Elmos » E523.30, E523.32, E523.38

E523.32: Position Recognition with no Sensor – LIN Interface

With the E523.32, Elmos is presenting a bipolar stepper motor driver IC with sinusoidal motor current modulation. The component is addressed via the LIN1.3 or LIN2.x interface. Its LIN address in the network can be permanently assigned or automatically defined using auto-addressing according to the SNPD LIN specification. This IC does not have to be programmed and, as a plug & play solution, features a wide variety of configuration options. An integrated E2PROM stores these application-specific configurations.

Elmos - E523.32

The IC was developed especially for use in vehicles. Possible applications include headlight adjustment, adaptive headlights, radiator grille flap control and the operation of water valves. It can also be used in engine compartment actuating drives thanks to the large temperature range from –40 °C to +165 °C. The voltage range is 5.5 V to 42 V.

The IC can record the end position of the stepper motor without a sensor. This function known as “stall detection” has been proven millions of times in the field for years. It detects the mechanical end position of the motor and stops it in order to minimise noise development during initialisation, and in case of mechanical defects in order to diagnose them and prevent further overloading. Errors occurring in the position information in case of blocking are reduced to a minimum by a special correction algorithm.

The IC generates a sinusoidal motor current with a programmable peak value of up to 800 mA per phase. This current control generates a constant motor torque regardless of the actual supply voltage value. It allows highly reliable torque control even with very low-ohm stepper motors.

With the 3 different current ranges of 300 mA, 600 mA and 800 mA, each of which can be generated with 8-bit resolution, exact sinusoidal current profiles can be generated even with lower motor currents. This leads to very low-noise and soft motor operation under all conditions.

Configuration options in the area of decay control, edge steepness etc. support the optimisation of system performance along with extensive diagnosis possibilities.

Next to the E523.32, the IC is also available as the E523.30 with freely programmable microcontroller and flash memory or, for large volumes, as the E523.38 with mask-programmable ROM. These versions enable software adaptations for various LIN protocols, non-sinusoidal current modulations and special application behaviour. Control via a PWM interface is possible as well. Alternative DC motors can also be controlled, and up to 3 external sensors can be supplied and evaluated.

The chip is supplied in the QFN32L6 housing.

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