SBAS688E April   2015  – September 2017 AFE5816

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (continued)
  6. Device Family Comparison Table
  7. Pin Configuration and Functions
  8. Specifications
    1. 8.1  Absolute Maximum Ratings
    2. 8.2  ESD Ratings
    3. 8.3  Recommended Operating Conditions
    4. 8.4  Thermal Information
    5. 8.5  Electrical Characteristics: TGC Mode
    6. 8.6  Electrical Characteristics: CW Mode
    7. 8.7  Digital Characteristics
    8. 8.8  Output Interface Timing Requirements
    9. 8.9  Serial Interface Timing Requirements
    10. 8.10 Typical Characteristics: TGC Mode
    11. 8.11 Typical Characteristics: CW Mode
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Attenuator
        1. 9.3.1.1 Implementation
        2. 9.3.1.2 Maximum Signal Amplitude Support
        3. 9.3.1.3 Attenuator High-Pass Filter (ATTEN HPF)
      2. 9.3.2  Low-Noise Amplifier (LNA)
        1. 9.3.2.1 Input Signal Support in TGC Mode
        2. 9.3.2.2 Input Signal Support in CW Mode
        3. 9.3.2.3 Input Circuit
        4. 9.3.2.4 LNA High-Pass Filter (LNA HPF)
          1. 9.3.2.4.1 Disconnecting the LNA HPF During Overload
        5. 9.3.2.5 LNA Noise Contribution
      3. 9.3.3  High-Pass Filter (HPF)
      4. 9.3.4  Low-Pass Filter (LPF)
      5. 9.3.5  Digital TGC (DTGC)
        1. 9.3.5.1 DTGC Overview
        2. 9.3.5.2 DTGC Programming
          1. 9.3.5.2.1 DTGC Profile
            1. 9.3.5.2.1.1 Profile Selection
        3. 9.3.5.3 DTGC Modes
          1. 9.3.5.3.1 Programmable Fixed-Gain Mode
          2. 9.3.5.3.2 Up, Down Ramp Mode
          3. 9.3.5.3.3 External Non-Uniform Mode
          4. 9.3.5.3.4 Internal Non-Uniform Mode
            1. 9.3.5.3.4.1 Memory
              1. 9.3.5.3.4.1.1 Write Operation for the Memory
              2. 9.3.5.3.4.1.2 Read Operation for the Memory
            2. 9.3.5.3.4.2 Gain Curve Description for the Internal Non-Uniform Mode
        4. 9.3.5.4 Timing Specifications
      6. 9.3.6  Continuous-Wave (CW) Beamformer
        1. 9.3.6.1 16 × ƒcw Mode
        2. 9.3.6.2 8 × ƒcw and 4 × ƒcw Modes
        3. 9.3.6.3 1 × ƒcw Mode
        4. 9.3.6.4 CW Clock Selection
        5. 9.3.6.5 CW Supporting Circuits
      7. 9.3.7  Analog-to-Digital Converter (ADC)
        1. 9.3.7.1 System Clock Input
        2. 9.3.7.2 System Clock Configuration for Multiple Devices
      8. 9.3.8  LVDS Interface
        1. 9.3.8.1 LVDS Buffer
        2. 9.3.8.2 LVDS Data Rate Modes
          1. 9.3.8.2.1 1X Data Rate Mode
          2. 9.3.8.2.2 2X Data Rate Mode
      9. 9.3.9  ADC Register, Digital Processing Description
        1. 9.3.9.1 Digital Offset
          1. 9.3.9.1.1 Manual Offset Correction
          2. 9.3.9.1.2 Auto Offset Correction Mode (Offset Correction using a Built-In Offset Calculation Function)
        2. 9.3.9.2 Digital Average
        3. 9.3.9.3 Digital Gain
        4. 9.3.9.4 Digital HPF
        5. 9.3.9.5 LVDS Synchronization Operation
      10. 9.3.10 Power Management
        1. 9.3.10.1 Voltage-Controlled Attenuator (VCA) Power Management
        2. 9.3.10.2 Analog-to-Digital Converter (ADC) Power Management
    4. 9.4 Device Functional Modes
      1. 9.4.1 ADC Test Pattern Mode
        1. 9.4.1.1 Test Patterns
          1. 9.4.1.1.1 LVDS Test Pattern Mode
      2. 9.4.2 Partial Power-Up and Power-Down Mode
      3. 9.4.3 Global Power-Down Mode
      4. 9.4.4 TGC Configuration
      5. 9.4.5 Digital TGC Test Modes
        1. 9.4.5.1 ENABLE_INT_START and NEXT_CYCLE_WAIT_TIME
        2. 9.4.5.2 MANUAL_START
        3. 9.4.5.3 FLIP_ATTEN
        4. 9.4.5.4 DIS_ATTEN
        5. 9.4.5.5 Fixed Attenuation Mode
      6. 9.4.6 CW Configuration
      7. 9.4.7 TGC + CW Mode
    5. 9.5 Programming
      1. 9.5.1 Serial Peripheral Interface (SPI) Operation
        1. 9.5.1.1 Serial Register Write Description
        2. 9.5.1.2 Register Readout
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curves
    3. 10.3 Do's and Don'ts
    4. 10.4 Initialization Set Up
  11. 11Power Supply Recommendations
    1. 11.1 Power Sequencing and Initialization
      1. 11.1.1 Power Sequencing
      2. 11.1.2 PLL Initialization
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Power Supply, Grounding, and Bypassing
      2. 12.1.2 Board Layout
    2. 12.2 Layout Example
  13. 13Register Maps
    1. 13.1 Serial Register Map
      1. 13.1.1 Global Register Map
        1. 13.1.1.1 Description of Global Register
          1. 13.1.1.1.1 Register 0 (address = 0h)
      2. 13.1.2 ADC Register Map
        1. 13.1.2.1 Description of ADC Registers
          1. 13.1.2.1.1  Register 1 (address = 1h)
          2. 13.1.2.1.2  Register 2 (address = 2h)
          3. 13.1.2.1.3  Register 3 (address = 3h)
          4. 13.1.2.1.4  Register 4 (address = 4h)
          5. 13.1.2.1.5  Register 5 (address = 5h)
          6. 13.1.2.1.6  Register 7 (address = 7h)
          7. 13.1.2.1.7  Register 8 (address = 8h)
          8. 13.1.2.1.8  Register 11 (address = Bh)
          9. 13.1.2.1.9  Register 13 (address = Dh)
          10. 13.1.2.1.10 Register 14 (address = Eh)
          11. 13.1.2.1.11 Register 15 (address = Fh)
          12. 13.1.2.1.12 Register 16 (address = 10h)
          13. 13.1.2.1.13 Register 17 (address = 11h)
          14. 13.1.2.1.14 Register 18 (address = 12h)
          15. 13.1.2.1.15 Register 19 (address = 13h)
          16. 13.1.2.1.16 Register 20 (address = 14h)
          17. 13.1.2.1.17 Register 21 (address = 15h)
          18. 13.1.2.1.18 Register 23 (address = 17h)
          19. 13.1.2.1.19 Register 24 (address = 18h)
          20. 13.1.2.1.20 Register 25 (address = 19h)
          21. 13.1.2.1.21 Register 26 (address = 1Ah)
          22. 13.1.2.1.22 Register 27 (address = 1Bh)
          23. 13.1.2.1.23 Register 28 (address = 1Ch)
          24. 13.1.2.1.24 Register 29 (address = 1Dh)
          25. 13.1.2.1.25 Register 30 (address = 1Eh)
          26. 13.1.2.1.26 Register 31 (address = 1Fh)
          27. 13.1.2.1.27 Register 32 (address = 20h)
          28. 13.1.2.1.28 Register 33 (address = 21h)
          29. 13.1.2.1.29 Register 35 (address = 23h)
          30. 13.1.2.1.30 Register 36 (address = 24h)
          31. 13.1.2.1.31 Register 37 (address = 25h)
          32. 13.1.2.1.32 Register 38 (address = 26h)
          33. 13.1.2.1.33 Register 39 (address = 27h)
          34. 13.1.2.1.34 Register 40 (address = 28h)
          35. 13.1.2.1.35 Register 41 (address = 29h)
          36. 13.1.2.1.36 Register 42 (address = 2Ah)
          37. 13.1.2.1.37 Register 43 (address = 2Bh)
          38. 13.1.2.1.38 Register 44 (address = 2Ch)
          39. 13.1.2.1.39 Register 45 (address = 2Dh)
          40. 13.1.2.1.40 Register 47 (address = 2Fh)
          41. 13.1.2.1.41 Register 48 (address = 30h)
          42. 13.1.2.1.42 Register 49 (address = 31h)
          43. 13.1.2.1.43 Register 50 (address = 32h)
          44. 13.1.2.1.44 Register 51 (address = 33h)
          45. 13.1.2.1.45 Register 52 (address = 34h)
          46. 13.1.2.1.46 Register 53 (address = 35h)
          47. 13.1.2.1.47 Register 54 (address = 36h)
          48. 13.1.2.1.48 Register 55 (address = 37h)
          49. 13.1.2.1.49 Register 56 (address = 38h)
          50. 13.1.2.1.50 Register 57 (address = 39h)
          51. 13.1.2.1.51 Register 59 (address = 3Bh)
          52. 13.1.2.1.52 Register 60 (address = 3Ch)
          53. 13.1.2.1.53 Register 65 (address = 41h)
          54. 13.1.2.1.54 Register 66 (address = 42h)
          55. 13.1.2.1.55 Register 67 (address = 43h)
      3. 13.1.3 VCA Register Map
        1. 13.1.3.1 Description of VCA Registers
          1. 13.1.3.1.1  Register 192 (address = C0h)
          2. 13.1.3.1.2  Register 193 (address = C1h)
          3. 13.1.3.1.3  Register 194 (address = C2h)
          4. 13.1.3.1.4  Register 195 (address = C3h)
          5. 13.1.3.1.5  Register 196 (address = C4h)
          6. 13.1.3.1.6  Register 197 (address = C5h)
          7. 13.1.3.1.7  Register 198 (address = C6h)
          8. 13.1.3.1.8  Register 199 (address = C7h)
          9. 13.1.3.1.9  Register 200 (address = C8h)
          10. 13.1.3.1.10 Register 206 (address = CEh)
          11. 13.1.3.1.11 Register 230 (address = E6h)
      4. 13.1.4 DTGC Register Map
        1. 13.1.4.1 Description of DTGC Register
          1. 13.1.4.1.1 DTGC Registers
            1. 13.1.4.1.1.1  Register 1 (address = 1h)
            2. 13.1.4.1.1.2  Registers 2-160 (address = 2h-A0h)
            3. 13.1.4.1.1.3  Register 161 (address = A1h)
            4. 13.1.4.1.1.4  Register 162 (address = A2h)
            5. 13.1.4.1.1.5  Register 163 (address = A3h)
            6. 13.1.4.1.1.6  Register 164 (address = A4h)
            7. 13.1.4.1.1.7  Register 165 (address = A5h)
            8. 13.1.4.1.1.8  Register 166 (address = A6h)
            9. 13.1.4.1.1.9  Register 167 (address = A7h)
            10. 13.1.4.1.1.10 Register 168 (address = A8h)
            11. 13.1.4.1.1.11 Register 169 (address = A9h)
            12. 13.1.4.1.1.12 Register 170 (address = AAh)
            13. 13.1.4.1.1.13 Register 171 (address = ABh)
            14. 13.1.4.1.1.14 Register 172 (address = ACh)
            15. 13.1.4.1.1.15 Register 173 (address = ADh)
            16. 13.1.4.1.1.16 Register 174 (address = AEh)
            17. 13.1.4.1.1.17 Register 175 (address = AFh)
            18. 13.1.4.1.1.18 Register 176 (address = B0h)
            19. 13.1.4.1.1.19 Register 177 (address = B1h)
            20. 13.1.4.1.1.20 Register 178 (address = B2h)
            21. 13.1.4.1.1.21 Register 179 (address = B3h)
            22. 13.1.4.1.1.22 Register 180 (address = B4h)
            23. 13.1.4.1.1.23 Register 181 (address = B5h)
            24. 13.1.4.1.1.24 Register 182 (address = B6h)
            25. 13.1.4.1.1.25 Register 183 (address = B7h)
            26. 13.1.4.1.1.26 Register 185 (address = B9h)
            27. 13.1.4.1.1.27 Register 186 (address = BAh)
  14. 14Device and Documentation Support
    1. 14.1 Documentation Support
      1. 14.1.1 Related Documentation
    2. 14.2 Community Resources
    3. 14.3 Trademarks
    4. 14.4 Electrostatic Discharge Caution
    5. 14.5 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

Package Options

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

Layout

Layout Guidelines

Power Supply, Grounding, and Bypassing

In a mixed-signal system design, the power-supply and grounding design play a significant role. The device distinguishes between two different grounds: AVSS (analog ground) and DVSS (digital ground). In most cases, designing the printed circuit board (PCB) to use a single ground plane is adequate, but in high-frequency or high-performance systems care must be taken so that this ground plane is properly partitioned between various sections within the system to minimize interactions between analog and digital circuitry. Alternatively, the digital supply set consisting of the DVDD_1P8, DVDD_1P2, and DVSS pins can be placed on separate power and ground planes. For this configuration, tie the AVSS and DVSS grounds together at the power connector in a star layout. In addition, optical or digital isolators (such as the ISO7240) can completely separate the analog portion from the digital portion. Consequently, such isolators prevent digital noise from contaminating the analog portion. Table 22 lists the related circuit blocks for each power supply.

Table 22. Supply versus Circuit Blocks

POWER SUPPLY GROUND CIRCUIT BLOCKS(1)
AVDD_3P15 AVSS Reference voltage and current generator, LNA, VCNTRL, CW mixer, CW clock buffer, 16 × 16 cross-point switch, and 16-phase generator blocks
AVDD_1P9 AVSS Band-gap circuit, reference voltage and current generator, LNA, PGA, LPF, and VCA SPI blocks
AVDD_1P8 AVSS ADC analog, reference voltage and current generator, band-gap circuit, ADC clock buffer
DVDD_1P8 DVSS LVDS serializer and buffer, and PLL blocks
DVDD_1P2 DVSS ADC digital and serial interface blocks
See Figure 96 and Figure 97 for further details.

Reference all bypassing and power supplies for the device to their corresponding ground planes. Bypass all supply pins with 0.1-μF ceramic chip capacitors (size 0603 or smaller). In order to minimize the lead and trace inductance, the capacitors must be located as close to the supply pins as possible. Where double-sided component mounting is allowed, these capacitors are best placed directly under the package. In addition, larger bipolar decoupling capacitors (2.2 μF to 10 μF, effective at lower frequencies) can also be used on the main supply pins. These components can be placed on the PCB in close proximity (< 0.5 inch or 12.7 mm) to the device itself.

The device has a number of reference supplies that must be bypassed, such as BIAS_2P5, LNA_INCM, BAND_GAP, and SRC_BIAS. Bypass these pins with at least a 1-μF capacitor; higher value capacitors can be used for better low-frequency noise suppression. For best results, choose low-inductance ceramic chip capacitors (size 0402, > 1 μF) placed as close as possible to the device pins.

Board Layout

High-speed, mixed-signal devices are sensitive to various types of noise coupling. One primary source of noise is the switching noise from the serializer and the output buffer and drivers. For the device, care must be taken to ensure that the interaction between the analog and digital supplies within the device is kept to a minimal amount. The extent of noise coupled and transmitted from the digital and analog sections depends on the effective inductances of each supply and ground connection; smaller effective inductances of the supply and ground pins result in better noise suppression. For this reason, multiple pins are used to connect each supply and ground set. Low inductance properties must be maintained throughout the design of the PCB layout by the use of proper planes and layer thickness.

To avoid noise coupling through supply pins, keep sensitive input pins (such as the INM and INP pins) away from the AVDD_3P15 and AVDD_1P9 planes. For example, do not route the traces or vias connected to these pins across the AVDD_3P15 and AVDD_1P9 planes. That is, avoid the power planes under the INM and INP pins.

In order to maintain proper LVDS timing, all LVDS traces must follow a controlled impedance design. In addition, all LVDS trace lengths must be equal and symmetrical; keep trace length variations less than 150 mil (0.150 inch or 3.81 mm).

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

Additional details on the NFBGA PCB layout techniques can be found in the Texas Instruments application report SSYZ015 that can be downloaded from www.ti.com.

Layout Example

Figure 107 and Figure 108 illustrate example layouts for the top and bottom layers, respectively.

AFE5816 top_layer_sbas641.png Figure 107. Top Layer
AFE5816 bottom_layer_sbas641.png Figure 108. Bottom Layer

Figure 109 shows the routing of input traces and differential CW outputs.

AFE5816 inpt_routing_sbas641.png Figure 109. Input Routing

Figure 110 shows routing examples for different power planes.

AFE5816 grnd_plane_sbas641.png Figure 110. Ground Plane

Figure 111, Figure 112, and Figure 113 illustrate routing examples for different power planes.

AFE5816 avdd1p9_dvdd1p8_pwr_plane_sbas641.png Figure 111. AVDD_1P9 and DVDD_1P8 Power Plane
AFE5816 avdd_1p8_pwr_plane_sbas641.png Figure 112. AVDD_1P8 Power Plane
AFE5816 avdd3_dvdd1p2_pwr_plane_sbas641.png Figure 113. AVDD_3P15 and DVDD_1P2 Power Plane