L7203

The L7203 SPINDLE MOTOR IC includes a three phase brushless spindle motor controller and the power stage in switching mode. The L7203 is designed for both 5V and 12V OPTICAL DRIVE application requiring up to 1.8A peak of current.

The L7203 is realized in BCD5, a 0.7 mm Mixed technology.

The spindle motor position detection is carried out by means of a single comparator with hysteresis. In the start-up phase the "inductive sense start up method" is used to detect the rotor position, determining the direction of starting rotation.

L7203 procedure is implemented by a logic circuit on chip.

The L7203 applies three sinusoidal voltages to the motor coils.

L7203 is obtained through the application of the SMOOTH DRIVING concept.

L7203 is based on the idea of driving the motor winding through 3 sinusoidal voltages dephased of 120 degrees. The motor is controlled in voltage mode, so no current control compensation network is required.

Each profile is digitally described by 36 bytes stored in a ROM memory.

These sinusoidal signals are modulated by multiplying each sample by a value stored in the KVAL register. Using this kind of profiles it is possible to obtain great advantages such as torque ripple and acoustic noise reduction and lower EMI. An easier track following is ensured, since vibration are reduced.

The clock signal on the chip can be synchronized to the external application clock signal.

An internal circuit can limit the current. The threshold is fixed with a internal 0.2 V reference.

The L7203 generates:
- a current generator to define output voltage slew rate
- a 3.3 V reference to bias hall sensor.
- the HFG open drain output signal for speed regulation.

The L7203 includes :
- a circuit for thermal shutdown with hysteresis.
- a low voltage detector

In the STANDBY state the main functions of the device are turned off, in order to minimize the power consumption.

The STANDBY state of the L7203 is imposed by:
- Thermal shutdown
- stand by signal from mP