TDA5341 datasheet(8/28 Pages) PHILIPS

8 / 28 page

1997 Jul 10

Philips Semiconductors

Product speciﬁcation

Brushless DC motor and VCM drive circuit

with speed control

TDA5341

Table 2

Summary of uncontrolled modes

FAILURE

MOT1, 2 AND 3

VCM+ AND VCM

−

RESETOUT

EFFECT

Thermal

shut-down

high impedance

→ LOW

VCM

− = 0.65 V;

VCM+ = 0 V

LOW

automatic park and brake

Voltage

shut-down

high impedance

→ LOW

VCM

− = 0.65 V;

VCM+ = 0 V

LOW

automatic park and brake

Controlled modes

SPINDLE DISABLE

The spindle circuitry is switched off when bit 23 (SPINDLE

DISABLE) of the serial port is pulled HIGH. In that mode,

the reference band gap generator is cut off so that all

internal current sources are disabled. Both the spindle and

actuator outputs will be set to the high impedance state

because the upper converter is also turned off.

It should be noted that the uncommitted operational

amplifier is also disabled in that mode.

VCM DISABLE

The actuator will be disabled when bit 22 (VCM DISABLE)

is set to logic 1; the spindle circuitry is not affected in that

mode. The retract circuitry also remains active, so that the

heads can be parked although the VCM is disabled. In that

mode, the current consumption can be reduced by

±4 mA.

SLEEP MODE

The sleep mode is obtained by pulling both the SPINDLE

and VCM DISABLE bits of the serial port HIGH. The power

monitor circuitry only remains active in sleep mode.

RETRACT

Retract is activated by pulling either bit 21 (PARK) HIGH

or RETRACT (pin 30) LOW. When RETRACT is set LOW,

a voltage of 0.65 V is applied to pin VCM

− for parking.

It should be noted that the park voltage can be made

adjustable by changing one of the interconnect masks.

Accordingly, some different voltages, varying from

0.2 to 1.2 V, can quickly be obtained on customer

demand. This mode does not affect the control of the

spindle rotation.

BRAKE MODE

The brake mode is activated by pulling BRAKE (pin 11)

LOW. When a voltage of less than 0.8 V is applied to pin

BRAKE, the 3 motor outputs are short-circuited to ground,

which results in a quick reduction of the speed until the

motor stops completely.

FRICTION REDUCTION

Pulling FREDENA HIGH activates the friction reduction

mode of the TDA5341. In that mode, a clock signal fed via

pin TESTIN will cause the MOT outputs to sequentially

switch-on and switch-off at the same frequency and, as a

result, generate an AC spindle torque high enough to

overcome the head stiction.

Before start-up, the head stiction might be higher than

normal due to condensation between the head(s) and the

disk(s). Normal spin-up is not possible when this friction

torque is higher than the start-up torque of the spindle

motor. Spin-up is then only possible after friction has been

reduced by breaking the head(s) free. Bringing a static

friction system into mechanical resonance is an effective

method to break static friction head(s) free.

The resonance frequency is:

Where:

C = Stiffness of the head-spring(s) in direction of disk(s)

rotation, (N/m)

J = Inertia of the disk(s), (kg/m2).

The external clock input frequency must be:

A burst of n

× 6 clock pulse will bring the system into

resonance and break the heads free (n > 2). Once the

heads have been broken free, the normal spin-up

procedure can be applied.

It should be noted that the clock frequency must be smaller

than 40000/CAPCDM (nF).

res

-------





0.5

----





clk

-------





0.5

----





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