MP6517 – SINGLE-PHASE, BLDC, MOTOR DRIVER WITH INTEGRATED HALL SENSOR

MP6517 Rev.1.01

www.MonolithicPower.com

16

4/9/2018

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APPLICATION INFORMATION

Selecting the Input Capacitor

Place an input capacitor (C1) near VCC to keep

the input voltage stable and to reduce input

switching voltage noise and ripple. The input

capacitor impedance must be low at the

switching frequency. Ceramic capacitors with

X7R dielectrics are recommended for their low

ESR characteristics. Ensure that the ceramic

capacitance is dependent on the voltage rating.

The DC bias voltage and value can lose as

much as 50% of its capacitance at its rated

voltage rating. Leave enough voltage rating

margin when selecting the component. For

most applications, a 1μF to 10μF ceramic

capacitor is sufficient. In some applications, add

an additional, large, electrolytic capacitor to

absorb armature inductor energy if needed.

Selecting the PWM Input Resistor

When the input PWM signal rating is >6.5V,

which exceeds the PWM voltage rating, a

resistor (R2) is needed. The recommended

value is 499Ω.

Hall Sensor Position

The Hall sensor cell is located in the lower left

corner of the package (see Figure 7).

(X, Y, Z) = (540µm, 508µm, 80µm)

Figure 7: Hall Sensor Position

Input Clamping Zener Diode

To avoid voltage spikes caused by the energy

stored in the motor charges back to the input

capacitor side, add a voltage-clamping Zener

diode. For a 12V case, a 15V/SOD-323

package Zener diode is sufficient. If input

connection reserve protection is needed, a

diode in series with a Zener diode is

recommended (see Section 1 in Figure 8).

Input Snubber

Due

to

the

input

capacitor

energy

charge/discharge during the phase transition

soft switching, the input current has switching

cycle ringing. If needed, add a 2Ω resistor in

series with a 1µF capacitor as an R-C snubber

in parallel with an input capacitor. This prevents

switching cycle ringing efficiently (see Section 2

in Figure 8).