FAH4820 Ver la hoja de datos (PDF) - Fairchild Semiconductor

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FAH4820

Direct Driver for DC Motors (ERMs)

Fairchild Semiconductor 

Applications Information

Many of the FAH4820 functions can be controlled

through the I2C interface, but this application

demonstrates the device in default state when powered

up. In the default state; the device is enabled, overdrive

is disabled, input resistance is 10 kΩ, and the

differential drive voltage is set to 3.0 V. The device

design allows the user to leave the SCL and SDA line

floating. The differential outputs are held at ground until

the HEN pin is pulled HIGH, which causes the ERM to

rotate until the HEN signal is pulled LOW or a timer

circuit pulls the HEN signal LOW. Figure 9 shows an

example using a 555 timer to control a single vibration

from an ERM. The length of time the ERM is rotating is

determined by the RC time constant of R3 and C3. In

this case, the motor rotate for 1.1 second every time the

button is pressed. Electromagnetic Interference (EMI) is

the radiation of electromagnetic noise. This noise can

affect control signals and other electronics, which can

produce errors and reduce performance. The DC

motors used in ERMs are a common source of EMI due

to commutator arcing. It is recommended that a 100 pF

capacitor be placed across the MDP and MPN pins. In

this case, this is C2, which greatly reduces EMI

produced by the ERM.

VCC_3V3

C1

100n

C2

100pF

ERM

U5

FAH4820

1

VDD

2

GND

3

MDP

4

MDN

5

GAIN

10

SCL

9

SDA

8

HEN

7

GND

6

NC

R2 100K

LM555

5

3

6 C VOL

OUT 7

THRES

DIS

4

2 RST

TRIG

8

VCC

R3

10K

Momentary

S1

C3

100uF

Figure 9. 555 Timer Control of Single Vibration from ERM

© 2013 Fairchild Semiconductor Corporation

FAH4820 • 1.0.0

10

www.fairchildsemi.com

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