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

Preliminary data sheet

Rev. 01 — 19 July 2004

11 of 24

Philips Semiconductors

SA56202

One-chip motor driver

for easy interfacing to 3 V and 5 V logic.

7.7 Sled motor driver

Two current-steering PWM channels are available to drive a stepper motor. Per channel

control loop is implemented that modulates the duty cycle of the PWM signal. See

Figure 9.

Input-to-output transconductance gain can be scaled down by connecting an external

Transconductance gain,

Limit current,

Fig 9.

Peak-current control architecture of stepper motor driver.

Fig 10. Transfer function of stepper motor driver.

Σ

001aaa435

M

R

S

Q

CLOCK

70 kHz

LOGIC

DRIVE

DRIVER

A

VINSLD

Rsense

IO

Rext

47 k

Ω

+

−

47 k

Ω

input amplifier

001aaa436

−1 A

+1 A/V

+1 A/V

1 A

dead zone

30 mV

−30 mV

I

o

V

in

--------

1

2R

sense

×

------------------------

=

I

LIM

1V

2R

sense

×

------------------------

=