NS7520B-1-I46 Digi International, NS7520B-1-I46 Datasheet - Page 61

• 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

External oscillator vs. internal PLL circuit
System clock generation (NS7520 clock module)
controller,
mode hardware configuration," beginning on page 50.
The NS7520 clock module creates the BCLK and FXTAL signals. Both signals are used
internally, but BCLK can also be accessed at ball A6 by setting the BCLKD field in the
System Control register to 0 (see "System Control register," beginning on page 63).
The clock module uses either an external oscillator or the internal PLL circuit to
produce the BCLK and FXTAL signals. When using an external oscillator, the minimum
high/low time on XTALA1 is 4.5ns.
The PLLTST, BISTEN, and SCANEN signals work together to choose between using the
external oscillator or the internal PLL circuit in the boundary scan or JTAG debugger
modes, as shown:
0
0
0
0
1
1
1
1
PLLTST
BCLK functions as the system clock and provides the majority of the
NS7520’s timing.
FXTAL provides the timing for the DRAM refresh counter, can be selected
instead of BCLK to provide timing for the watchdog timer, the two internal
timers, and the Serial module.
{PLLTST_, BISTEN_,
0
0
1
1
0
0
1
1
BISTEN
0
1
0
1
0
1
0
1
SCANEN
and
SCANEN_}
N/A
N/A
N/A
External oscillator, boundary scan
NA (See Figure 5.)
N/A
PLL, JTAG debugger
External oscillator, JTAG debugger
FUNCTION
must be set as shown in "External oscillator
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