AN1451 datasheet(33/43 Pages) STMICROELECTRONICS

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AN1451 APPLICATION NOTE

4.2 EVAL6208N

An evaluation board has been produced to help the evaluation of the device in PowerDIP package. It imple-

ments a typical application with several added components. Figure 37 shows the electrical schematic of the

board; in the table below the part list is reported.

CN1, CN2, CN3, CN4 2-poles connector

100

Ω resistor

CN5

34-poles connector

820

Ω 0.6W resistor

220nF/100V Ceramic or Polyester capacitor R3, R4, R5, R6, R7, R8

10k

Ω resistor

220nF/100V Ceramic or Polyester capacitor R9

4.7k

Ω resistor

100µF/63V capacitor

R10, R21

20k

Ω 1% resistor

10nF/100V Ceramic capacitor

R11, R12

100k

Ω trimmer

10µF/16V Capacitor

R13, R22

2.2k

Ω resistor

100nF Capacitor

R14, R15, R16, R17, R18, R191

Ω 0.4W resistor

C7, C8

68nF Capacitor

R20, R24

Ω trimmer

C9, C10

820pF Capacitor

quad switch

D1, D2

1N4148 Diode

L6208N

BZX79C5V1 5.1V Zener Diode

JP1

3-pin jumper

The Evaluation Board provides external connectors for the supply voltage, an external 5V reference for the logic

inputs, four outputs for the motor and a 34-pin connector to control the main functions of the board through an

external µC board or the PractiSPIN tool.

The PractiSPIN tool is composed of a graphic interface software running on a PC that connects with the hard-

ware based on the ST7 µC, which contains an upgradeable firmware. This tool allows a fast and easy evaluation

of the PowerSPIN family devices, giving the ability of setting the decay mode, the stepping sequence, the output

current; to control the motor speed, acceleration and deceleration and to program a sequence of movements.

The PC-software also provides a Power Dissipation and Thermal Analysis section, intended to help a fast eval-

uation of the device, package and dissipating copper area required by the user’s application, and to be a good

starting point designing an application (from the power dissipation and thermal point of view).

Running the evaluation board in stand-alone mode, instead, four switches (S1) allow enabling the device, set-

ting the direction of the rotation, the type of current decay, the stepping sequence. R20 and R24 set the refer-

ence voltage separately for the two bridges, while R13, C7 and R22, C8 are low-pass filters to provide an

external reference voltage by a PWM output of a µC (see also the Microstepping section). Using external VREF

inputs R10, R20, R21, R24 must be disconnected unless the PractiSPIN ST7 evaluation board is used. This

board, in fact, is provided with an offset cancellation circuitry trimmable through a potentiometer (see PractiSPIN

documentation). R11, C9 and R12, C10 are used to set the off-time of the two channels of the IC.

The 5V voltage for logic inputs and for references (VrefA and VrefB) is obtained from R2, D3. Depending on the

supply voltage, the value of resistor R2 should be changed in order to ensure a correct biasing of D3.

The jumper JP1 allows choosing the 5V voltage from the internal zener diode network or pin 11 of CN5 (for ex-

ample an external µC board can provide 5V to the evaluation board). Also CN2 connector can be used to pro-

vide an external 5V voltage to the board (in that case R2, D3 should be disconnected). CN2, or pin 1 of CN5,

can also be used to provide a 5V voltage to external circuits (as, for example, the PractiSPIN ST7 board). In this

case the current that can be drawn form the board depends on the supply voltage and on R2 value.

Figure 38, Figure 39, Figure 40 show the component placement and the two layers layout of the L6208N Eval-

uation Board. A large GND area has been used, to guarantee minimal noise and good power dissipation for the

device.

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