MC3PHAC Motorola, MC3PHAC Datasheet - Page 39

• Manufacturer Part Number: MC3PHAC
• Description: 3-Phase AC Motor Controller
• Manufacturer: Motorola

Optoisolated RS232 Interface Application Example
MOTOROLA
CON/CANNON9
FEMALE
J1
5
9
4
8
3
7
2
6
1
GND
DTR
TxD
RTS
RxD
~+12 V
1N4148
Some motor control systems have the control electronics operating at the same
potential as the high voltage bus. Connecting a PC to that system could present
safety issues, due to the high voltage potential between the motor control
system and the PC.
used with the MC3PHAC to isolate the serial port of the PC from the motor
control system.
The circuit in
interface. This isolated terminal interface provides a margin of safety between
the motor control system and a personal computer. The EIA RS232
specification states the signal levels can range from ±3 to ±25 volts. A Mark is
defined by the EIA RS232 specification as a signal that ranges from –3 to –25
volts. A Space is defined as a signal that ranges from +3 to +25 volts.
Therefore, to meet the RS232 specification, signals to and from a terminal must
transition through 0 volts as it changes from a Mark to a Space. Breaking the
circuit down into an input and output section simplifies the explanation of the
circuit.
D3
Freescale Semiconductor, Inc.
ISOLATION BARRIER
For More Information On This Product,
Figure 19. Optoisolated RS232 Circuit
D2
1N4148
R3
4.7 k
1N4148
3-Phase AC Motor Controller
Figure 19
Go to: www.freescale.com
D1
HALF-DUPLEX, MAXIMUM 9600 BAUD
+
C1
2.2 F/50 V
1 k
Figure 19
R1
RS232 ISOLATED
4
5
is the schematic of a half-duplex optoisolated RS232
1
2
4N35
4N35
is an example of a simple circuit that can be
U1
U2
1
2
Optoisolated RS232 Interface Application Example
4
5
330
R4
+5 V
R2
1 k
+5 V
TO MC3PHAC PIN 16
TO MC3PHAC PIN 17
MC3PHAC/D
39