Usb I/F Control Circuit - Citizen CL-E700 series Technical Manual

Chapter 2 Operating Principles
2-2.
Operation of Control Parts

(5) USB I/F control circuit

The USB (Universal Serial Bus) I/F circuit interfaces with the USB I/F.
The comparator (U15A) and Q12 consist of a USB connection detecting circuit.
When a USB connector is connected to the printer, pin 1 (VBUS) of connector J12 goes to
"High" level. Thus, Q12 turns OFF, pin 176 (USBVBUS0) of the CPU (U1A) goes to "High" level,
and USB connection is detected.
The data transmission is carried out via pins 174 (USBDM0) and 175 (USBDP0) of the CPU.
H: USB connected
L: USB disconnected
U1A
CPU
176
VBUSIN0
USBVBUS0
DTC115TM
174
USBDM0
DM0
175
USBDP0
DP0
CL-E700 series
+5.0V
+5.0V
R108
R110
R109
1
C135
Q12
U15A
BA2903SFVM
+5.0V
+3V
R107
R112
C134
+ 3
2
-
VBUS0
R114 C136
R115
C138
L6
Diode Array
(Transient Voltage Supressor)
2-42
A certain voltage is applied when
a USB connector is connected.
L5
R113
D6
C137
L7
D7
[SA Main PCB]
J12
USB I/F
1
VBUS
2
2
1
D-
3
D+
3 4
4
GND
5
SHLD