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© Koninklijke Philips Electronics N.V. 2004. All rights reserved.

Preliminary data sheet

Rev. 01 — 19 July 2004

8 of 24

Philips Semiconductors

SA56202

One-chip motor driver

back-EMF voltage is part of these motor voltages.

7.3 Sine generation using True-Silent signals

For the phase relation between the Hall inputs and the spindle outputs in forward rotation,

see Figure 7. These are the signal shapes in sine mode using our True-Silent PWM

technology. The particular shape of the 120

° symmetrical U, V and W steering voltages

are because of improved drive strength and improved power efficiency. The drive strength

is improved because with this signal shape a 15 % larger sine can be fit within the supply

rails compared to direct-written sine signals. Also the power efficiency is improved

because this signal shape has 33 % less switching losses compared to a direct-written

sine.

The result is that the motor currents (and motor torques) are pure sine waves generated in

such a way that the motor is driven optimally silent, optimally power efficient and with

maximum driving strength.

Fig 6.

Motor voltages when accelerating and braking with constant motor current.

001aaa432

accelerating

braking

2

2

2

0

0

ωmax

ωω

0

k