Demonstration board description AN2757
6/10
The input lines CW/CCW, CONTROL, HALF / FULL, EN and RESET are connected to
ground through a pull-down resistor which sets the low logic level as default. An external
signal can be applied to change each input status.
D1, C1 and C4 constitute a charge pump circuit, which generates the supply voltage for the
high-side integrated MOSFETs. Due to voltage and current switching at relatively high
frequency, these components are connected through short paths in order to minimize
induced noise on other circuitries.
R1 and C5 are used by the overcurrent protection integrated circuitry (disable time t
DISABLE
is about 200 µs and delay time t
DELAY
about 1 µs using the values in Table 3.).
R6, C6 and R7, C7 are used to set the off-time t
OFF
of the two PWM channels to about
50 µs. The off-time should be adjusted according to the motor electrical characteristics and
supply voltage by changing the R6, C6 and R7, C7 values.
R11, R12, C8 and R13, R14, C9 are low-pass filters which provide an external reference
voltage through a PWM output of a microcontroller.
Figure 4, Figure 5 and Figure 6 show the placement of the components and the layout of the
two layers of the EVAL6228QR reference design board. A GND area has been used to
improve the IC power dissipation.
Table 3. EVAL6228QR part list
Part reference Part value Part description
C1 220 nF / 25 V Capacitor
C2 220 nF / 63 V Capacitor
C3 100 µF / 63 V Capacitor
C4 10 nF / 25 V Capacitor
C5 5.6 nF Capacitor
C6, C7 820 pF Capacitor
C8, C9 220 nF Capacitor
D1 BAT46SW Diode
R1, R2, R3, R4, R5, R8 100 kΩ 5% 0.25 W Resistor
R6, R7 100 kΩ 1% 0.25 W Resistor
R9, R10 0.4 Ω 1 W Resistor
R11, R13 20 kΩ 1% 0.25 W Resistor
R12, R14 2 kΩ 1% 0.25 W Resistor
U1 L6228Q Stepper motor driver in VFQFPN5x5
