MA100 Datasheet, PDF (4/9 Pages) Extech Instruments Corporation. – 200A AC Mini Clamp Meter/Voltage Detector

Application Notice
Megawin MA100 Application Circuit
U2
VBus
D-
D+
GND
VDD
R3 30
D-
D+
R4 30
C5
1u
C6
30P
C7
30P
XTAL1
6MHZ
XTAL2
VCC_UART VCC_UART
RX
Device A
TX
R1
4.7k
R2
4.7k
TX
RX
C4
VDD
15P
U1
VDD
V3.3 1
D- 2 ^V3.3
28 D+
D+ ₂₇
3 ^D-
Vcc _{26 USB_LED}
C2
C1
USB_LED
LED D1
C3
15P
XTAL1
XTAL2
4
5
6
Vss USB_LED
XTAL1 RX_LED
XTAL2 TX_LED
25
24
23
RX_LED
TX_LED
0.1u
10u
RX_LED
LED D2
TX
RX
7 ^NC
8 ^TX
9 ^RX
-RST ₂₂
BS2
BS1
21
20
C8
0.1u
TX_LED
LED D3
10 ^LBRS
BS0 ₁₉
11 ^P0
NC ₁₈
12
13
EE_A0
EE_A1
TO1
TO0
17
16
14
EE_SCL
EE_SDA
NC
NC
15
MA100L
Optional
U3
EE_A0 1
EE_A1 2
GND 3
GND 4
A0 VCC
A1 WP
A2 SCL
GND SDA
5
6
7
8
AT24C08
VDD
GND
EE_SCL
EE_SDA
If the power of device A is more than 4.0V,
R1 and R2 must be connected to VCC_UART which is the power of device A.
Otherwise, VCC_UART should be 3.3V applied by MA100.
Title
Megawin Technology Inc.
Size
Document Number
A _{Megawin MA100 Application Circuit}
Date:
Friday, May 19, 2006
Sheet
1
Rev
1.1
of
1
1. Time-out between RX and USB:
Time-out = 1/baud rate x 2ⁿ, 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