Application information

L6258EX

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4

Application information

A typical application circuit is shown in Figure 11.

Note:

For avoid current spikes on falling edge of DISABLE a "DC feedback" would be added to the

ERROR Amplifier. (R1-R2 on Figure 11).

4.1

Interference

Due to the fact that the circuit operates with switch mode current regulation, to reduce the

effect of the wiring inductance a good capacitor (100nF) can be placed on the board near

the package, between the power supply line (pin 13,31) and the power ground (pin

1,36,18,19) to absorb the small amount of inductive energy.

It should be noted that this capacitor is usually required in addition to an electrolytic

capacitor, that has poor performance at the high frequencies, always located near the

package, between power supply voltage (pin 13,31) and power ground (pin 1,36,18,19), just

to have a current recirculation path during the fast current decay or during the phase

change.

The range value of this capacitor is between few µF and 100µF, and it must be chosen

depending on application parameters like the motor inductance and load current amplitude.

A decoupling capacitor of 100nF is suggested also between the logic supply and ground.

The EA_IN1 and EA_IN2 pins carry out high impedance lines and care must be taken to

avoid coupled noise on this signals. The suggestion is to put the components connected to

this pins close to the L6258EX, to surround them with ground tracks and to keep as far as

possible fast switching outputs of the device. Remember also an 1 Mohm resistor between

EA_INx and EA_OUTx to avoid output current spike during supply startup/shutdown.

A non inductive resistor is the best way to implement the sensing. Whether this is not

possible, some metal film resistor of the same value can be paralleled.

The two inputs for the sensing of the winding motor current (SENSE_A & SENSE_B) should

be connected directly on the sensing resistor Rs terminals, and the path lead between the

Rs and the two sensing inputs should be as short as possible.

Note:

Connect the DISABLE pin to a low impedance (< 300

minimum the interference on the output current due to capacitive coupling of OUT1A (pin5)

and DISABLE (pin 6).