AD5940
Data Sheet
Bits
2
Bit Name
Settings Description
High frequency crystal oscillator enable. This bit is used to enable and disable the
Reset Access
HFXTALEN
HFOSCEN
LFOSCEN
0x0
0x1
0x1
R/W
R/W
R/W
oscillator. The oscillator must be stable before use. This bit must be set before the
SYSRESETREQ system reset can be initiated.
0
1
The high frequency crystal oscillator is disabled and placed in a low power state.
The high frequency crystal oscillator is enabled.
1
0
High frequency internal oscillator enable. This bit is used to enable and disable the
oscillator. The oscillator must be stable before use. This bit must be set before the
SYSRESETREQ system reset can be initiated.
0
1
The high frequency oscillator is disabled and placed in a low power state.
The high frequency oscillator is enabled.
Low frequency internal oscillator enable. This bit is used to enable and disable the
oscillator. The oscillator must be stable before use.
0
1
The low frequency oscillator is disabled and placed in a low power state.
The low frequency oscillator is enabled.
High Power Oscillator Configuration Register—HSOSCCON
Address 0x000020BC, Reset: 0x00000034, Name: HSOSCCON
Table 175. Bit Descriptions for HSOSCCON Register
Bits
Bit Name
Settings Description
Reset Access
[31:3] Reserved
Reserved.
0x3
0x1
R
R/W
2
CLK32MHZEN
16 MHz/32 MHz output selector signal. This bit determines if the output is 32 MHz
or 16 MHz. The ADC can run at 32 MHz, but system clock cannot run at 32 MHz. It
is required to divide the system clock by 2 first before switching the oscillator to
32 MHz. Refer to the SYSCLKDIV bit in the CLKCON0 register.
0
1
Select 32 MHz output.
Select 16 MHz output.
Reserved.
[1:0]
Reserved
0x0
R
Key Protection for RSTCON Register—RSTCONKEY
Address 0x00000A5C, Reset: 0x0000, Name: RSTCONKEY
Table 176. Bit Descriptions for RSTCONKEY Register
Bits
Bit Name Settings Description
Reset Access
[15:0] KEY
Reset control key register. SWRSTCON is key protected with a value of 0x12EA. Write to 0x0
W
the SWRSTCON register after the key is entered. A write to any other register before
writing to SWRSTCON returns the protection to the lock state.
Internal Low Frequency Oscillator Register—LOSCTST
Address 0x00000A6C, Reset: 0x0088, Name: LOSCTST
Table 177. Bit Descriptions for LOSCTST Register
Bits
[15:4]
[3:0]
Bit Name
Reserved
TRIM
Settings Description
Reset Access
Reserved.
0x8
0x8
R/W
R/W
Trim capacitors to adjust frequency. The output frequency can be trimmed by
adjusting the charging capacitors.
Rev. 0 | Page 124 of 130
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