Motor driver ICs 3-phase motor driver BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS The BA6840BFS, BA6840BFP-Y, BA6840BFP, and BA6842BFS are one-chip ICs designed for driving CD-ROM motors. They are high performance-ICs with a 3-phase, full-wave, pseudo-linear drive system. Applications CD-ROM / RW, DVD-ROM / PLAYER Features 1) 3-phase, full-wave, pseudo-linear drive system. 2) Start / stop pin; power saving during stop mode. 3) Internal current limit circuit. 4) Internal thermal shutdown circuit. 5) Internal hall bias circuit. Block diagram 523 Motor driver ICs BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions 524 Motor driver ICs BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 5V, VM = 12V) 525 Motor driver ICs Electrical characteristic curves 526 BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS Motor driver ICs BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS Circuit operation (1) Hall input output The 3-phase Hall signal is amplified in the hall amplifiers and sent to the matrix section, where the signal is further amplified and combined. After the signal is converted to a current in the amplitude control circuit, the current is supplied to the output driver, which then provides a motor drive current. The phases of the Hall input signal, output voltage, and output current are shown in Fig. 5. (2) Torque control pin The RNF-pin current depends on the torque control input voltage (EC) as shown in Fig. 6. (3) Start / stop pin The motor is in the run mode when the pin input voltage is 3.5V or more, and in the idle mode (all output transistors are off) when the voltage is 1.5V or less. (4) Power ground pin (RNF pin) The RNF pin is the output stage ground pin. Connect a resistor (0.5Ω recommended) between this pin and the ground to monitor the output current. (5) Phase compensation pin (CNF pin) Connect and adjust a capacitor between this pin and the ground if the output tends to oscillate. 527 Motor driver ICs BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS Pin descriptions Input / output circuits (1) Start / stop 528 (2) Reversing pin (3) Hall bias Motor driver ICs BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS (4) Torque control input (6) Hall input (H1), H1*, H2), H2*, H3), H3*) (5) Coil output FOperation notes (1) Start / stop The I / O equivalent circuit of the start / stop pin is shown in Fig. 7. The pin has a temperature dependence of *7mV / _C, and the resistance can vary ±30%. Take the temperature effect into consideration when designing your application. (2) Hall input The Hall input equivalent circuit is shown in Fig. 12. The Hall devices can be connected in either series or parallel. (3) Thermal shutdown circuit (TSD) The circuit puts the coil outputs (A1, A2, and A3) to the open state at the temperature of 175_C (typical). There is a temperature difference of about 15_C between the temperatures at which the circuit is activated and deactivated. 529 Motor driver ICs Application example 530 BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS Motor driver ICs BA6840BFS / BA6840BFP-Y / BA6840BFP / BA6842BFS External dimensions (Units: mm) 531