cs5954am Cypress Semiconductor Corporation., cs5954am Datasheet - Page 9

• Manufacturer Part Number: cs5954am
• Description: Usb Controller For Nand Flash
• Manufacturer: Cypress Semiconductor Corporation.

4.4
The CS5954AM has an option to use either a 48-MHz or 12-MHz external crystal or oscillator as its clock source. CS5954AM
includes an internal PLL that can be configured by software. At power-up, the CS5954AM BIOS default configuration sets the
processor clock to run at 2/3 of XIN (of the external provided clock).
Example 1 Changing CS5954AM CPU Speed
Document #: 38-08025 Rev. **
The default of the CS5954AM BIOS assumes a 48-MHz input clock, so the CS5954AM processor clock is (2/3)*48 MHz = 32
MHz. See example below.
If the XIN input clock is 48 MHz, then the maximum speed of the CS5954AM processor can be set as follows:
If the XIN input clock is 12 MHz, then the maximum speed of the CS5954AM processor can be set to:
Clock Generator
mov
mov
mov
mov
mov
mov
[0xC006],0x10
[0xC008],0
[0xC006],0
[0xC008],0
[0xC006],0x40
[0xC008],0
XIN
Cbk
0.01 F
Lin
2.2 - 3.3 H
;clock = 2/3*XIN
;CPU clock at 32 MHz
;clock = set up at XIN clock input
;CPU clock at 48 MHz
;clock = 4*XIN
;CPU clock at 48 MHz
48 MHz, series, 20-pF load
Figure 4-1. 48-MHz Crystal Circuit
ADVANCE
INFORMATION
Rf
1M
X1
XOUT
Rs
100
Cout
22 pF
CS5954AM
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