TSC2012IST datasheet(42/54 Pages) STMICROELECTRONICS

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5.13

Application examples

5.13.1

Half-bridge motor control

The half-bridge topology is very popular in motor control, DC-DC converters, LED lighting control and other

bidirectional loads from a single supply potential.

The TSC2011 provides a feedback control system about current but also detects overload conditions.

The Figure 79. Half-bridge application describes a typical schematic using the TSC2011 in a motor control

application. A 20 mΩ shunt resistance in series with the motor monitors a measurable voltage drop representing

the load current, and the TSC2011 amplifies the Vsense in order to give some information about the current flowing

into the motor in real time. These information are then digitalizing by the 12-bit ADC (ADC120).

Figure 79. Half-bridge application

General overview:

To make the motor rotation occur, the NMOS H1, H2, L1, L2 are driven by a half-bridge quad power MOSFET

driver. We have to consider that the current flows from the 12 V to the GND, through H1 NMOS and L2 NMOS. A

PWM is applied on the NMOS L2 in order to control the current and thus the speed of the motor.

By PWM, the average voltage applied on the motor is controlled. H1 remains always ON and the PWM is applied

on L2. When L2 is turned off, H2 must be turned ON, for freewheeling, allowing the discharge of the motor

inductance current. This phenomenon generates a fast input common mode voltage transition on the TSC2011,

from 0 V to 12 V.

Thanks to a good recovery time due to fast input common mode change, the TSC2011 follows the current flowing

into the motor as depicted by the scope probe in Figure 80. TSC2011 H Bridge application.

The black curve represents the fast Vicm variation step of 12 V in 500 ns when the freewheeling is activated. The

blue curve represents the current flowing into the motor measured with a current probe.

The red curve represents the output voltage - 1.35 V (Vref voltage) of the TSC2011 probe after the RC filter.

The RC filter, used to drive the ADC120, smooths a bit the output signal and adds a small constant time, in the

range of 1 µs.

TSC2010, TSC2011, TSC2012

Application examples

DS13057 - Rev 4

page 42/54

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