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What is the diffrance between a Brushed ESC (electronic speed controller) and a Brushed DC Motor Driver (controller)? they both do the same job, yet at different prices and look diffrent.

Example:

Motor driver datasheet: http://nvhs.files.wordpress.com/2013/02/datasheet-l9110.pdf

ESC datasheet: http://www.hobbywing.com/uploadfiles/sx/file/manual/HW-05.pdf

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  • \$\begingroup\$ Depends on what you think a "ESC" is. \$\endgroup\$ Aug 10, 2013 at 11:27
  • \$\begingroup\$ @OlinLathrop Electronic speed controller, for example this is an esc: ebay.com/itm/… and this is a motor controller: dx.com/p/… \$\endgroup\$ Aug 10, 2013 at 11:28
  • \$\begingroup\$ @DanBarzilay, after a quick look one is rated at 800mA and only a chip whereas the other is a complete module rated at 20A. So they don't really do the same job and I'd expect the latter to be significantly more expensive. \$\endgroup\$
    – PeterJ
    Aug 10, 2013 at 12:00
  • \$\begingroup\$ It's like trying to compare a basic gearbox with a motor car (which of course also has a gearbox, but in addition it has an engine, a steering wheel suspension, doors, a roof and a radio). \$\endgroup\$
    – Andy aka
    Aug 10, 2013 at 14:47

3 Answers 3

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The main difference is that ESC you linked is a complete module meant to be used by the end user. On the other hand, the motor controller you linked is just a bare component which is meant to be integrated in a module. So the target audience is different. Motor controller is expected to be used by an engineer (or at least experienced hobbyist) who has necessary electronics knowledge to make it work, while use of ESC often requires drastically lower level of electronics knowledge since often only thing that needs to be known is to follow assembly diagram.

Motor controller is the main part of the ESC, but there (usually) are other components as well which are used on an ESC to provide complete module. For example, the ESC is supposed to be connected to a radio which will output some type of signal. That signal is not necessarily what motor controller expects, so there may be need for a conversion stage.

Also ESC will often have a protection mechanism which will turn off motor when battery voltage is too low, while motor controllers often do not have that protection.

Depending on the power ratings, ESC could use a motor controller made from discrete components instead of an IC motor controller.

The exact difference is a bit fuzzy, since there is a tendency of integrating as many features as possible on a single IC, so some features which ESC module would provide using components other than the motor controller would find themselves integrated onto the motor controller.

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  • \$\begingroup\$ Thanks, good answer, just one more question, so why aren't there ESCs for less than 1A? \$\endgroup\$ Aug 10, 2013 at 12:13
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    \$\begingroup\$ Because there's basically no market for them. Even the smallest common hobby-grade R/C craft draw a fair fraction of an amp at full throttle. \$\endgroup\$ Aug 10, 2013 at 12:31
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The so-called brushed DC motor controller in the question is merely a dual half H-bridge IC with some inductive load protection. In other words, it is similar to the well-known L293 and L293D dual half H-bridge devices. The pin-out is simpler, providing just the pins required to drive the H-bridge and thus an attached DC motor forwards or backwards. There is no speed control, no internal PWM clock, and no logic built-in for modifying motor speed.

A brushed DC ESC on the other hand consists of not only H-bridge functionality, but also a PWM clock and PWM drive capability at the output. Thus the motor can be directly speed controlled by an ESC, without providing any external clock source or control logic.

The ESC in the question incorporates a Battery Elimination Circuit (BEC), a standard Radio Control (RC) throttle-signal input from an external RC receiver, speed control through a 2 KHz PWM, an alarm function with integrated speaker for indicating error conditions, overheating fold-back, and logic via its on-board microcontroller to gracefully handle loss of control signal in a pre-programmed manner - by throttling down the motor(s) if signal is lost for 1 second or longer.

Also, the current ratings for the specific ESC series mentioned are 20-50 Amperes, way higher than the pretty anemic L9110 H-bridge IC rated at just 800 mA.

There is no reason to expect the two devices, with their vastly different functional descriptions, to be even somewhat similar.

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  • \$\begingroup\$ But the motor controller is a speed controller, the input is PWM signal which controls the speed of the motor, isn't it? \$\endgroup\$ Aug 10, 2013 at 12:50
  • \$\begingroup\$ The motor controller is purely a H-bridge, not a speed controller. You can always take any switch or H-bridge and feed it PWM as a control signal, and if it is designed to handle the PWM frequency, it will work in PWM mode. That does not make it a speed controller. The ESC actually generates PWM signals as per received throttle signal, that is a speed controller. \$\endgroup\$ Aug 10, 2013 at 12:58
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In general, an ESC provides an interface between an RC receiver and a motor. In addition, some ESCs can also use the back EMF of the motor to provide closed-loop control. An ESC also converts a servo control signals (~1to2ms pulses @ 60 Hz) to something more appropriate to motor speed control.

A motor driver such as an H-bridge simply provides a way to connect/disconnect each motor connection to a power supply rail through transistors. By doing so, you can operate the motor in forward, reverse or braking modes with a microcontroller. There is no control loop although som circuitry for implementing that may be provided. It will respond to PWM signal duty cycle, so the motor speed can be controlled.

If you are using a standard RC transmitter/receiver pair, you want to use an ESC unless you are up for quite a bit of circuit building. If you just want to use a microcontroller to drive a motor with PWM, then the motor driver is all you need.

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