Application Notice

Title

Size

Document Number

Rev

Date:

Sheet

of

11

Friday, May 19, 2006

Megawin MA100 Application Circuit

1.1

Megawin Technology Inc.

A

V3.3

1

D-

2

Vss

3

XTAL1

4

XTAL2

5

NC

6

TX

7

RX

8

LBRS

9

P0

10

EE_A0

11

EE_A1

12

EE_SCL

13

EE_SDA

14

NC

15

NC

16

TO0

17

TO1

18

NC

19

BS0

20

BS1

21

BS2

22

-RST

23

TX_LED

24

RX_LED

25

USB_LED

26

Vcc

27

D+

28

U1

MA100L

D1

LED

D2

LED

D3

LED

USB_LED

TX_LED

XTAL1

VDD

6MHZ

XTAL2

XTAL2

VCC_UART

VCC_UART

If the power of device A is more than 4.0V,

Otherwise, VCC_UART should be 3.3V applied by MA100.

R1 and R2 must be connected to VCC_UART which is the power of device A.

VDD

R3

30

R4

30

VBus

D-

D+

VDD

GND

U2

A0

1

A1

2

A2

3

GND

4

VCC

5

WP

6

SCL

7

SDA

8

U3

AT24C08

EE_A0

EE_A1

GND

GND

VDD

GND

EE_SCL

EE_SDA

D-

D+

RX_LED

TX_LED

RX

USB_LED

TX

XTAL1

Optional

RX

TX

Device A

D-

TX

R1

4.7k

D+

R2

4.7k

RX

V3.3

C4

15P

Megawin MA100 Application Circuit

C5

1u

C2

0.1u

C1

10u

C3

15P

RX_LED

C6

30P

C8

0.1u

C7

30P

1. Time-out between RX and USB:

Time-out = 1/baud rate x 2

n

, where n=0 for TO1=1 and TO0=1, n=1 for TO1=1 and TO0=0;

n=2 for TO1=0 and TO0=1, n=3 for TO1=0 and TO0=0.

2. TX/RX-pin is an open-drain pin:

The TX/RX is an open-drain circuit, So, It decide that how much the suspend current, That is,

If the power of device A is more than 4.0V, The VCC_UART’s power must be connect to the power

of device A, Otherwise, The VCC_UART’s power should be connect to V3.3 pin of the MA100

3. UART’s TX data delay

There is a time gap between the bytes transmitted via MA100’s TX-pin. When the frequency of

oscillator is 6 MHz, the minimum time gap is 10 microseconds. Users need to make sure the UART

receiver device could move the data from the receiving buffer during the time gap, 10 us, to avoid it

being overwritten by the following byte of data. The signal timing is shown in the following.

4

MA100 Data Sheet

MEGAWIN