AN2836 datasheet(41/57 Pages) STMICROELECTRONICS

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AN2836

Demonstration boards

Doc ID 15084 Rev 1

41/57

The demonstration 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 PractiSPINTM tool. The

board also accommodates the L6506 PWM current controller. R23 sets the PWM operating

frequency. If the L6506 does not need to be used, simply connect the two VREF inputs to a

voltage high enough to keep current control inactive.

The PractiSPINTM tool is composed of a graphic interface software running on a PC that

connects with the hardware based on the ST7 µC, which contains upgradable firmware. This

tool allows a fast and easy evaluation of the powerSPINTM family of devices, allowing to

drive DC, BLDC and stepper motors, depending on the target device. The practiSPIN

connected to the EVAL6225PD can drive DC motors and inductive loads, allowing output

voltage and current settings.

The PC software also provides a power dissipation and thermal analysis section, intended

to help give a fast evaluation of the device, package and dissipating copper area required by

the user’s application, and to be a good starting point for designing an application (from the

power dissipation and thermal point of view).

Running the demonstration board in standalone mode, instead, R17 and R21 set the

reference voltage separately for the two bridges, while R16, C9 and R20, C12 are low-pass

filters which provide an external reference voltage by a PWM output of a

µC (see also the

microstepping section in the AN2839). Using external VREF inputs, R15, R17, R19, R21 can

be disconnected through JP4 and JP5, unless the PractiSPINTM ST7 demonstration board

is used. This board, in fact, is provided with an offset cancellation circuitry trimmable

through a potentiometer (see PractiSPINTM documentation). Closing JP2 and JP3 is

recommended for safe overcurrent protection.

The 5 V 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 5 V voltage from the internal Zener diode network or

pin 11 of CN5 (for example an external µC board can provide 5 V to the demonstration

board). Also a CN2 connector can be used to provide an external 5 V 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 5 V voltage to external circuits (as, for example, the PractiSPINTM ST7 board). In

R7, R9, R10, R12

Ω 0.4 Ω

Resistor

R18, R14

1 k

Resistor

R15, R19

20 k

Resistor

R16, R20

2.2 k

Resistor

R17, R21

5 k

Trimmer

R22

12 k

Resistor

R23

50 k

Trimmer

L6225PD

L6506D

JP2, JP3, JP4, JP5, JP6

2-pole

Jumper

Table 4.

EVAL6225PD part list (continued)

Part reference

Value

Description

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