SLOS738E September   2012  – August 2015 AFE5809

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics
    6. 7.6  Digital Demodulator Electrical Characteristics
    7. 7.7  Digital Characteristics
    8. 7.8  Switching Characteristics
    9. 7.9  SPI Switching Characteristics
    10. 7.10 Output Interface Timing Requirements (14-bit)
    11. 7.11 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 LNA
      2. 8.3.2 Voltage-Controlled Attenuator
      3. 8.3.3 PGA
      4. 8.3.4 ADC
      5. 8.3.5 Continuous-Wave (CW) Beamformer
        1. 8.3.5.1 16 × ƒcw Mode
        2. 8.3.5.2 8 × ƒcw and 4 × ƒcw Modes
        3. 8.3.5.3 1 × ƒcw Mode
      6. 8.3.6 Digital I/Q Demodulator
      7. 8.3.7 Equivalent Circuits
      8. 8.3.8 LVDS Output Interface Description
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
      1. 8.5.1 Serial Peripheral Interface (SPI) Operation
        1. 8.5.1.1 ADC/VCA Serial Register Write Description
        2. 8.5.1.2 ADC/VCA Serial Register Readout Description
        3. 8.5.1.3 Digital Demodulator SPI Description
    6. 8.6 Register Maps
      1. 8.6.1 ADC and VCA Register Description
        1. 8.6.1.1 ADC Register Map
        2. 8.6.1.2 AFE5809 ADC Register/Digital Processing Description
          1. 8.6.1.2.1  AVERAGING_ENABLE: Address: 2[11]
          2. 8.6.1.2.2  ADC_OUTPUT_FORMAT: Address: 4[3]
          3. 8.6.1.2.3  ADC Reference Mode: Address 1[13] and 3[15]
          4. 8.6.1.2.4  DIGITAL_GAIN_ENABLE: Address: 3[12]
          5. 8.6.1.2.5  DIGITAL_HPF_ENABLE
          6. 8.6.1.2.6  DIGITAL_HPF_FILTER_K_CHX
          7. 8.6.1.2.7  LOW_FREQUENCY_NOISE_SUPPRESSION: Address: 1[11]
          8. 8.6.1.2.8  LVDS_OUTPUT_RATE_2X: Address: 1[14]
          9. 8.6.1.2.9  CHANNEL_OFFSET_SUBSTRACTION_ENABLE: Address: 3[8]
          10. 8.6.1.2.10 SERIALIZED_DATA_RATE: Address: 3[14:13]
          11. 8.6.1.2.11 TEST_PATTERN_MODES: Address: 2[15:13]
          12. 8.6.1.2.12 SYNC_PATTERN: Address: 10[8]
        3. 8.6.1.3 VCA Register Map
        4. 8.6.1.4 VCA Register Description
          1. 8.6.1.4.1 LNA Input Impedances Configuration (Active Termination Programmability)
          2. 8.6.1.4.2 Programmable Gain for CW Summing Amplifier
          3. 8.6.1.4.3 Programmable Phase Delay for CW Mixer
      2. 8.6.2 Digital Demodulator Register Description
        1. 8.6.2.1 Profile RAM and Coefficient RAM
          1. 8.6.2.1.1 Programming the Profile RAM
          2. 8.6.2.1.2 Procedure for Configuring Next Profile Vector
          3. 8.6.2.1.3 Programming the Coefficient RAM
          4. 8.6.2.1.4 Filter Coefficent Test Mode
          5. 8.6.2.1.5 TX_SYNC and SYNC_WORD Timing
          6. 8.6.2.1.6 FIR Filter Delay versus TX_TRIG Timing
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 LNA Configuration
          1. 9.2.2.1.1 LNA Input Coupling and Decoupling
          2. 9.2.2.1.2 LNA Noise Contribution
          3. 9.2.2.1.3 Active Termination
          4. 9.2.2.1.4 LNA Gain Switch Response
        2. 9.2.2.2 Voltage-Controlled Attenuator
        3. 9.2.2.3 CW Operation
          1. 9.2.2.3.1 CW Summing Amplifier
          2. 9.2.2.3.2 CW Clock Selection
          3. 9.2.2.3.3 CW Supporting Circuits
        4. 9.2.2.4 Low Frequency Support
        5. 9.2.2.5 ADC Operation
          1. 9.2.2.5.1 ADC Clock Configurations
          2. 9.2.2.5.2 ADC Reference Circuit
      3. 9.2.3 Application Curves
    3. 9.3 System Example
      1. 9.3.1 ADC Debug
      2. 9.3.2 VCA Debug
    4. 9.4 Do's and Don'ts
      1. 9.4.1 Driving the Inputs (Analog or Digital) Beyond the Power-Supply Rails
      2. 9.4.2 Driving the Device Signal Input With an Excessively High Level Signal
      3. 9.4.3 Driving the VCNTL Signal With an Excessive Noise Source
      4. 9.4.4 Using a Clock Source With Excessive Jitter, an Excessively Long Input Clock Signal Trace, or Having Other Signals Coupled to the ADC or CW Clock Signal Trace
      5. 9.4.5 LVDS Routing Length Mismatch
      6. 9.4.6 Failure to Provide Adequate Heat Removal
  10. 10Power Supply Recommendations
    1. 10.1 Power/Performance Optimization
    2. 10.2 Power Management Priority
    3. 10.3 Partial Power-Up and Power-Down Mode
    4. 10.4 Complete Power-Down Mode
    5. 10.5 Power Saving in CW Mode
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

11 Layout

11.1 Layout Guidelines

Proper grounding and bypassing, short lead length, and the use of ground and power-supply planes are particularly important for high-frequency designs. Achieving optimum performance with a high-performance device such as the AFE5809 requires careful attention to the PCB layout to minimize the effects of board parasitics and optimize component placement. A multilayer PCB usually ensures best results and allows convenient component placement. To maintain proper LVDS timing, all LVDS traces should follow a controlled impedance design. In addition, all LVDS trace lengths should be equal and symmetrical; TI recommends to keep trace length variations less than 150 mil (0.150 inch or 3.81 mm).

NOTE

To avoid noise coupling through supply pins, TI recommends keeping sensitive input net classes, such as INM, INP, ACT pins, away from AVDD 3.3 V, AVDD_5V, DVDD, AVDD_ADC, DVDD_LDO1/2 nets or planes. For example, vias connected to these pins should NOT be routed across any supply plane. That is to avoid power planes under INM, INP, and ACT pins.

In addition, appropriate delay matching should be considered for the CW clock path, especially in systems with high channel count. For example, if clock delay is half of the 16× clock period, a phase error of 22.5°C could exist. Thus, the timing delay difference among channels contributes to the beamformer accuracy.

Additional details on BGA PCB layout techniques can be found in the TI application report MicroStar BGA Packaging Reference Guide (SSYZ015), which can be downloaded from www.ti.com.

11.2 Layout Example

AFE5809 Laye1.gifFigure 114. Layout Example
AFE5809 Layer2.gifFigure 115. Layout Example
AFE5809 Layer3.gifFigure 116. Layout Example
AFE5809 Layer4.gifFigure 117. Layout Example