NS7520B-1-I46 Digi International, NS7520B-1-I46 Datasheet - Page 70

• Manufacturer Part Number: NS7520B-1-I46
• Description: IC ARM MICROPROCESSOR 177BGA
• Manufacturer: Digi International
• Series: NET+ARM®r

Specifications of NS7520B-1-I46

• Applications: Network Processor
• Core Processor: ARM7
• Program Memory Type: External Program Memory
• Controller Series: -
• Ram Size: External
• Interface: EBI/EMI, Ethernet, DMA, SPI, UART
• Number Of I /o: 16
• Voltage - Supply: 1.4 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 177-LFBGA
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

5 8
S e t t i n g t h e P L L f r e q u e n c y
PLL frequency. The NS7520 resets whenever the PLLCNT field is changed, then starts
running at the new frequency dictated by the PLLCNT value. The readback value is
not valid until software has performed a write to this register.
When using a 18.432MHz crystal, the 4-bit value in the PLLCNT field produces
frequencies of 23MHz to 92.2MHz, in increments of 4.6MHz, by changing the IS and ND
fields in the PLL Settings register.
Notes:
The FS field remains the same as configured on bootup.
The IS field is ‘b10 for all standard frequencies from 36.9MHz to 55.3MHz.
The ND field can be changed to 16 different values based on the PLLCNT.
The next table shows the 16 frequencies that can be produced by changing
the PLLCNT field in the PLL Control register.
23.0
27.6
32.3
36.9
41.5
46.1
50.7
55.3
59.9
64.5
69.1
73.7
78.3
82.9
87.6
92.2
MHz
N S 7 5 2 0 H a r d w a r e R e f e r e n c e , R e v G 9 / 2 0 0 7
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
PLLCNT
01
01
01
10
10
10
10
10
10
10
10
11
11
11
11
11
IS
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
ND+1
0x00000084
0x00000085
0x00000086
0x00000087
0x00000108
0x00000109
0x0000010A
0x0000010B
0x0000010C
0x0000010D
0x0000010E
0x0000010F
0x00000110
0x00000111
0x00000112
0x00000113
PLL Settings register
1
2
3
Notes