Datasheet
Table Of Contents
- FEATURES
- APPLICATIONS
- DESCRIPTION
- ABSOLUTE MAXIMUM RATINGS
- ELECTRICAL CHARACTERISTICS
- DIGITAL CHARACTERISTICS
- FUNCTIONAL BLOCK DIAGRAM
- PIN CONFIGURATION
- TIMING CHARACTERISTICS
- LVDS OUTPUT TIMING CHARACTERISTICS
- LVDS OUTPUT TIMING CHARACTERISTICS
- TYPICAL CHARACTERISTICS
- SERIAL INTERFACE
- SERIAL REGISTER MAP
- SUMMARY OF FEATURES
- DESCRIPTION OF SERIAL REGISTERS
- THEORY OF OPERATION
- APPLICATION INFORMATION
- REVISION HISTORY
AFE5805
www.ti.com
SBOS421D –MARCH 2008–REVISED MARCH 2010
LOW-FREQUENCY NOISE SUPPRESSION MODE
ADDRESS
IN HEX D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 NAME
X X X X LFNS_CH<1:4>
14
X X X X LFNS_CH<8:5>
The low-frequency noise suppression mode is especially useful in applications where good noise performance is
desired in the frequency band of 0MHz to 1MHz (around dc). Setting this mode shifts the low-frequency noise of
the AFE5805 to approximately f
S
/2, thereby moving the noise floor around dc to a much lower value.
LFNS_CH<8:1> enables this mode individually for each channel.
LVDS TEST PATTERNS
ADDRESS
IN HEX D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 NAME
X 0 0 EN_RAMP
0 X 0 DUALCUSTOM_PAT
25 0 0 X SINGLE_CUSTOM_PAT
X X BITS_CUSTOM1<11:10>
X X BITS_CUSTOM2<11:10>
26 X X X X X X X X X X BITS_CUSTOM1<9:0>
27 X X X X X X X X X X BITS_CUSTOM2<9:0>
0 X PAT_DESKEW
45
X 0 PAT_SYNC
The AFE5805 can output a variety of test patterns on the LVDS outputs. These test patterns replace the normal
ADC data output. Setting EN_RAMP to '1' causes all the channels to output a repeating full-scale ramp pattern.
The ramp increments from zero code to full-scale code in steps of 1LSB every clock cycle. After hitting the
full-scale code, it returns back to zero code and ramps again.
The device can also be programmed to output a constant code by setting SINGLE_CUSTOM_PAT to '1', and
programming the desired code in BITS_CUSTOM1<11:0>. In this mode, BITS_CUSTOM<11:0> take the place of
the 12-bit ADC data at the output, and are controlled by LSB-first and MSB-first modes in the same way as
normal ADC data are.
The device may also be made to toggle between two consecutive codes by programming DUAL_CUSTOM_PAT
to '1'. The two codes are represented by the contents of BITS_CUSTOM1<11:0> and BITS_CUSTOM2<11:0>.
In addition to custom patterns, the device may also be made to output two preset patterns:
1. Deskew patten: Set using PAT_DESKEW, this mode replaces the 12-bit ADC output D<11:0> with the
010101010101 word.
2. Sync pattern: Set using PAT_SYNC, the normal ADC word is replaced by a fixed 111111000000 word.
Note that only one of the above patterns can be active at any given instant.
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