NS7520B-1-I46 Digi International, NS7520B-1-I46 Datasheet - Page 62

• 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

NS7520 clock module block diagram
External oscillator mode hardware configuration
5 0
U s i n g t h e e x t e r n a l o s c i l l a t o r
Using the external oscillator
This diagram provides an overview of the clock module.
The NS7520 can use an external oscillator to generate the BCLK and FXTAL signals. In
this type of configuration, the BCLK frequency is equal to the oscillator input
frequency. The FXTAL frequency is equal to the oscillator input frequency divided by
five. For example, with a 55MHz oscillator, BCLK would be 55 MHZ and FXTAL would
be 11MHz.
Note:
The external oscillator’s output is connected to the XTALA1 input through a 100
resistor. XTALA2 is an output and is left open.
FXTAL
BCLK
SCANEN
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
Using an external oscillator with PLL enabled is not advantageous, due to
the PLL input limitation of 10MHz to 20MHz. The oscillator needs to be the
same frequency as the crystal. Using a clock source greater than 20MHz
would result in the PLL running outside its operating range.
/5
PLLTST
oscillator
External
BISTEN
External
crystal
circuit
PLL
PLL Settings reg
PLL Control reg
A[8:0]