Instrument Cluster Stepper Motor for Automobile Speedometer

1. Product Description
MDR29 series stepper motor is specially designed for indicator components (such as pointer) used to drive vehicle instrumentation and other precision indicator devices that directly accept the digital signal of the system, drive the pointer to a location to indicate the required parameters, without Digital-to-Analog Converter.


2. Main Features
1) Compact appearance: Ф30mm x 26.8mm. 
2) Low consumption: operation current less than 18mA. 
3) Low noise: lower than 40dB(A), durable and acoustic material for gear. 
4) Wide operation temperature range: -40 to 105°C. 
5) High precision: 1/3° step angle in partial-step mode, 1/12° step angle at micro-step mode.
6) High reliability and long service life: comply with automotive industrial standards.


3. Typical Application
The typical application of MDR29 series stepper motor is used for automobile instrument cluster, motorcycle dashboard.


4. Operating Pinciple
Through the built-in 4-gear transmission system with 1/180 deceleration ratio, the pointer shaft will rotate 1° while the rotor rotates 180° driven by a full-step driving signal.
And in partial-step mode, the pointer shaft will rotate 1/3° while the rotor rotates 60°.
In order to make motor run more stably and decrease the noise especially when pointer loaded on pointer shaft, micro-step mode is recommended. The micro pulse sequence, which is more precise and near to sine wave, could drive pointer shaft to rotate 1/12º at each micro step.

5. Parameter
Note: fz = testing frequency, JL = testing pointer inertia, Ub = operating voltage
Ta=25ºC, Ub=5V, useless unless specified.

6. Installation
MDR29 series stepper motor can be easily installed on PCB, the welding spots of 4 pins are well protected to ensure reliable connection even under extremely strong vibration operating condition, as it supports mounting by screw.
In general, screws are not necessary for cost and process considerations and should be avoided as much as possible. In the absence of screws, although the motor has a sturdy design, it should be taken care to prevent excessive force, avoid damage to the motor casing and other parts inside. Especially during the assembly of the pointer, we strongly recommend adding a support at the bottom of the motor to counteract the force exerted on the pointer shaft to prevent it from damaging the motor.