L6258 datasheet(13/18 Pages) STMICROELECTRONICS

13 / 18 page

ACloaddB

= 20 ⋅ log







− Bemf

⋅

+ RS







we can see that the Bemf influences only the gain

of the load block and does not introduce any

other additional pole or zero, so from the stability

point of view the effect of the Bemf of the motor is

not critical because the phase margin remains the

same.

Practically the only effect of the Bemf is to limit

the gain of the total Aloop with a consequent vari-

ation of the bandwidth of the system.

APPLICATION INFORMATION

A typical application circuit is shown in Fig.4.

Note: For avoid current spikes on falling edge of

DISABLE a "DC reaction" would be added

to the ERROR Amplifier. (R1-R2 on Fig. 4).

Interference

Due to the fact that the circuit operates with

switch mode current regulation, to reduce the ef-

fect 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 re-

quired in addition to an electrolytic capacitor, that

has poor performance at the high frequencies, al-

ways 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 induc-

tance and load current amplitude.

A decoupling capacitor of 100nF is suggested

also between the logic supply and ground.

A non inductive resistor is the best way to imple-

ment 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 mo-

tor current (SENSE_A & SENSE_B) should be

connected directly on the sensing resistor Rs ter-

minals, and the path lead between the Rs and the

two sensing inputs should be as short as possi-

ble.

STEPPER

MOTOR

12mH 10

Ω

0.33

OUT2B

SENSE2

OUT2A

SENSE1

OUT1B

OUT1A

PH1

I0_1

I1_1

I2_1

I3_1

PH2

I0_2

I1_2

I2_2

I3_2

DISABLE

10nF

100nF

1nF

TRI_CAP

GND

VBOOT

VCP2

VCP1

13,31

1,36

18,19

PWR_GND

SIG_GND

D97IN626D

VREF1

VREF2

EA_IN1

EA_OUT1

820pF

EA_IN2

EA_OUT2

820pF

VREF

VDD

VDD(5V)

L6258

SOP36

PACKAGE

R2 1M

R1 1M

Figure 4: Typical Application Circuit.

L6258

13/18

L6258 数据表(PDF) 13 Page - STMicroelectronics

L6258 数据表(HTML) 13 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

数据表下载