Application information L6258EA
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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 L6258, 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
Ω
) voltage source to reduce at
minimum the interference on the output current due to capacitive coupling of OUT1A (pin5)
and DISABLE (pin 6).
