Rainbow Electronics AT89C5122 User Manual
Page 16
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AT8xC5122/23
4202E–SCR–06/06
PSEN
15
-
24
-
15
-
VCC
O
Program Strobe Enable: The read strobe to external program
memory. When executing code from the external program memory,
PSEN is activated twice each machine cycle, except that two PSEN
activations are skipped during each access to external data memory.
PSEN is not activated during fetches from internal program memory.
PLLF
54
26
67
27
54
26
AVCC
O
PLL Low Pass Filter input
Receives the RC network of the PLL low pass filter.
AVCC
55
27
68
28
55
27
PWR
Analog Supply Voltage
AVCC is used to supply the internal 3.3V analog regulator which
supplies the internal USB driver
VCC
20
12
31
15
20
12
PWR
Supply Voltage
VCC is used to supply the internal 3.3V digital regulator which
supplies the PLL, CPU core and internal I/O’s
LI
18
10
29
13
18
10
PWR
DC/DC Input
LI supplies the current for the charge pump of the DC/DC converter.
- LI tied directly to VCC : the DC/DC converter must be configured in
regulator mode.
- LI tied to VCC through an external 10µH coil : the DC/DC converter
can be configured either in regulator or in pump mode.
CVCC
17
9
28
12
17
9
PWR
Card Supply Voltage
CVCC is the ouput of internal DC/DC converter which supplies the
Smart Card Interface. It must be connected to an external decoupling
capacitor of 10 µF with the lowest ESR as this parameter influences
on the CVCC noise
DVCC
1
1
10
5
1
1
PWR
Digital Supply Voltage
DVCC is the output of the internal analog 3.3V regulator which
supplies the USB driver. This pin must be connected to an external
680nF decoupling capacitor if the USB interface is used.
This output can be used by the application with a maximum of 10 mA.
CVSS
19
11
30
14
19
11
GND
DC/DC Ground
CVSS is used to sink high shunt currents from the external coil
VSS
16
8
25
11
16
8
GND
Digital Ground
VSS is used to supply the PLL, buffer ring and the digital core
AVSS
53
25
66
26
53
25
GND
Analog Ground
AVSS is used to supply the USB driver.
Table 2. Pin Description (Continued)
Port
VQ
FP
6
4
VQ
FP
3
2
P
L
CC6
8
P
L
CC2
8
QF
N
6
4
QF
N
3
2
Internal
Power
Supply
ESD
I/O
Reset
Level
Alt
Reset
Config
Conf 1
Conf 2
Conf 3
Led