AS8410 datasheet(10/19 Pages) AMSCO

10 / 19 page

PWM DC Motor Regulator – Data Sheet

AS8410

Rev. 1.0, December 2000

page 10 of 19

4 Functional Description and Electrical

P a rameters

The main functions of this PWM-Switch-Regulator are summarised in section 1.3.

The normal regulation loop is build by an analogue difference-integrator, both the input set

value at pin IN and the measured motor current (at pins CMp and CMn) are transformed to the

chip internal control signals. The difference signal is integrated on the capacitor connected to

the pin Cint1 and the voltage at this pin is controlling the PWM generator and closes so the

regulation loop. So the regulation time constant can be determined in width range by the exter-

nal capacitor at the pin Cint1.

The AS8410 can be used in two different modes controlled by the pin MODE :

Operating Mode 1 (OM1: VMODE = high):

The set value must be given at pin IN as the duty ration of a low frequency digital

signal (fIN > 10 Hz).

The Over Temperature reaction: 100 % duty ratio of the FET-driver output (perma-

nent switch on the motor) as long as the temperature is higher than the predefined

threshold value (typical automotive application, the heating source is not the electri-

cal system but the combustion engine).

Operating Mode 2 (OM2: VMODE = low):

The set value must be given at pin IN as analogue voltage in the range

VIN = 0 … 5 V

The Over Temperature reaction: The motor is regulated down to not cross the pre-

defined temperature threshold (like a thermostat if the heating source is the electrical

system itself).

The adaptation of the AS8410 to the DC motor (nominal motor current and power FET) will be

realised by the value of the motor current measurement resistor Rmeas and by the slew rate con-

trolling currents into the pins SRC1 and SRC2 as described in section 3.4.1.

The detection of the different kinds of motor failures is realised by comparing the actual meas-

ured motor working point and the normal motor characteristic. Each motor failure is then treated

by the AS8410 with an adapted failure handling procedure described in section 3.4.2.

A failure report signal is generated and sent to the pin IN by pull down this pin.

Also the over temperature and the over / under voltage failure are treated by the AS8410 itself.

AS8410 Datasheet(PDF) 10 Page - ams AG