Digi manual Using the external oscillator, NS7520 clock module block diagram

Models: NS7520

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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

PLLTST

BISTEN

SCANEN

FUNCTION

 

 

 

 

1

0

0

PLL, boundary scan

 

 

 

 

1

0

1

N/A

 

 

 

 

1

1

0

PLL, JTAG debugger

 

 

 

 

1

1

1

External oscillator, JTAG debugger

 

 

 

 

NS7520 clock module block diagram

This diagram provides an overview of the clock module.

FXTAL

BCLK

/5

External oscillator

External

crystal

PLL

circuit

A[8:0]

PLL Settings reg

PLL Control reg

SCANEN

PLLTST

BISTEN

Using the external oscillator

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.

5 0

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 . D 0 3 / 2 0 0 6

Page 64
Image 64
Digi manual Using the external oscillator, NS7520 clock module block diagram