KA8328 Просмотр технического описания (PDF) - Fairchild Semiconductor

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производитель

KA8328

2-PHASE DRUM MOTOR DRIVER

Fairchild Semiconductor 

VCR PRODUCTS

KA8328D

3.The whole system concept explained above can be expressed in a more detailed block diagram as follows.

Hall input

8

IN

I1

AMP

I2

+

−

I4

7

I3

9

GM

ICTL

2

−

+

IO

OUT

13 17

IO

13 17

Motor

3

Converter

R1

TSD

VREG

R2

10

<Whole system concept diagram>

AMP, GM (Feedback), and OUT (Driver) are blocks which determine, the gain (AT). The hall input functions as an

ON-OFF switch which is drived by the hall signal. Amp is an amplifier which amplifies the input current 4 times. GM

is a feedback circuit which returns the feedback of the output current (IO), and OUT (Driver) is the power switch

part which drives the motor.

VREG is a constant voltage source which supply stabilized voltage to each block.

TSD is the overheat protective circuit which protect IC from the overheat, that is, in the event of overheat it protect

IC through grounding the input part and OUT (Driver) part.

As for the input-output characteristic, if the input current ICTL=100µA is applied, then I1=100µA → I2 - I3 = 400µA

(=100µA × 4) → IO=490mA, so the current gain become 4900 times.

The output current is detected through the output current detecting resistance (R2), and transferred to the

feedback circuit (GM), and then again returned to OUT (Driver) as feedback, so the output current is kept constant

at a desired value.

As a result the motor speed is also kept constant.

MIC-99D001

7

January 1999

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