Electronic Components Datasheet Search |
|
BA6486FS Datasheet(PDF) 4 Page - Rohm |
|
BA6486FS Datasheet(HTML) 4 Page - Rohm |
4 / 11 page 547 Motor driver ICs BA6486FS FCircuit operation (1) Motor drive circuit The motor driver is based on a 3-phase, full-wave soft switching, current drive system in which the position of rotor is sensed by Hall elements. The total drive current of motor is sensed by a small resistor (RNF) and regulated through a voltage comparison. The IC consists of Hall amplifiers, an amplitude control circuit, a driver, an error amplifier, and current feedback ampifier (Fig. 1). The waveforms of different steps along the signal path from the Hall elements to the motor driver output are shown in Fig. 2. The Hall amplifiers receive the Hall ele- ments voltage signals as differential signals. Next, by de- ducting the voltage signal of Hall elements 2 from the voltage signal of Hall elements 1, current signal H1, which has a phase 30 degrees ahead of Hall element 1, is created. Current signals H2 and H3 are created like- wise. The amplitude control circuit then amplifies the H1, H2, and H3 signal according to the current feedback am- plifier signal. Then, drive current signals are produced at A1, A2, and A3 by applying a constant magnification fac- tor. Because a soft switching system is employed, the drive current has low noise and a low total current ripple. The total drive current is controlled by the error amplifier input voltage. The error amplifier has a voltage gain of about –11dB (a factor of 0.28). The current feedback am plifier regulates the total drive current, so that the error amplifier output voltage (V1) is equal to the VRNF voltage, which has been voltage-converted from the total drive current through the RNF pin. If V1 exceeds the current lim- iter voltage (Vcl), the constant voltage Vcl takes prece- dence, and a current limit is applied at the level of Vcl /RNF. The current feedback amplifier tends to oscillate be- cause it receives all the feedback with a gain of 0dB. To prevent this oscillation, connect an external capacitor to the CNF pin for phase compensation and for reducing the high frequency gain. (2) Speed control circuit The speed control circuit is a non-adjustable digital servo system that uses a frequency locked loop (FLL). The cir- cuit consists of an 1 / 2 frequency divider, an FG amplifier, and a speed discriminator (Fig. 14). An internal reference is generated from an external clock signal input. The 1 / 2 frequency divider reduces the fre- quency of the OSC signal. The FG amplifier amplifies the minute voltage generated by the motor FG pattern and produces a rectangular-shaped speed signal. The FG amplifier gain (GFG = 42dB, typical) is determined by the internal resistance ratio. |
Similar Part No. - BA6486FS |
|
Similar Description - BA6486FS |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |