JAJSEY1 April   2019 ADC12DJ5200RF

ADVANCE INFORMATION for pre-production products; subject to change without notice.  

  1. 特長
  2. アプリケーション
  3. 概要
    1.     ADC12DJ5200RF ブロック図
  4. 改訂履歴
  5. 概要 (続き)
  6. Pin Configuration and Functions
    1.     Pin Functions
  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: DC Specifications
    6. 7.6  Electrical Characteristics: Power Consumption
    7. 7.7  Electrical Characteristics: AC Specifications (Dual-Channel Mode)
    8. 7.8  Electrical Characteristics: AC Specifications (Single-Channel Mode)
    9. 7.9  Timing Requirements
    10. 7.10 Switching Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Device Comparison
      2. 8.3.2 Analog Inputs
        1. 8.3.2.1 Analog Input Protection
        2. 8.3.2.2 Full-Scale Voltage (VFS) Adjustment
        3. 8.3.2.3 Analog Input Offset Adjust
      3. 8.3.3 ADC Core
        1. 8.3.3.1 ADC Theory of Operation
        2. 8.3.3.2 ADC Core Calibration
        3. 8.3.3.3 Analog Reference Voltage
        4. 8.3.3.4 ADC Overrange Detection
        5. 8.3.3.5 Code Error Rate (CER)
      4. 8.3.4 Temperature Monitoring Diode
      5. 8.3.5 Timestamp
      6. 8.3.6 Clocking
        1. 8.3.6.1 Noiseless Aperture Delay Adjustment (tAD Adjust)
        2. 8.3.6.2 Aperture Delay Ramp Control (TAD_RAMP)
        3. 8.3.6.3 SYSREF Capture for Multi-Device Synchronization and Deterministic Latency
          1. 8.3.6.3.1 SYSREF Position Detector and Sampling Position Selection (SYSREF Windowing)
          2. 8.3.6.3.2 Automatic SYSREF Calibration
      7. 8.3.7 Digital Down Converters (DDC)
        1. 8.3.7.1 Numerically-Controlled Oscillator and Complex Mixer
          1. 8.3.7.1.1 NCO Fast Frequency Hopping (FFH)
          2. 8.3.7.1.2 NCO Selection
          3. 8.3.7.1.3 Basic NCO Frequency Setting Mode
          4. 8.3.7.1.4 Rational NCO Frequency Setting Mode
          5. 8.3.7.1.5 NCO Phase Offset Setting
          6. 8.3.7.1.6 NCO Phase Synchronization
        2. 8.3.7.2 Decimation Filters
        3. 8.3.7.3 Output Data Format
        4. 8.3.7.4 Decimation Settings
          1. 8.3.7.4.1 Decimation Factor
          2. 8.3.7.4.2 DDC Gain Boost
      8. 8.3.8 JESD204C Interface
        1. 8.3.8.1 Transport Layer
        2. 8.3.8.2 Scrambler
        3. 8.3.8.3 Link Layer
        4. 8.3.8.4 8B/10B Link Layer
          1. 8.3.8.4.1 Data Encoding (8B/10B)
          2. 8.3.8.4.2 Multiframes and the Local Multiframe Clock (LMFC)
          3. 8.3.8.4.3 Code Group Synchronization (CGS)
          4. 8.3.8.4.4 Initial Lane Alignment Sequence (ILAS)
          5. 8.3.8.4.5 Frame and Multiframe Monitoring
        5. 8.3.8.5 64B/66B Link Layer
          1. 8.3.8.5.1 64B/66B Encoding
          2. 8.3.8.5.2 Multiblocks, Extended Multiblocks and the Local Extended Multiblock Clock (LEMC)
          3. 8.3.8.5.3 Block, Multiblock and Extended Multiblock Alignment using Sync Header
            1. 8.3.8.5.3.1 Cyclic Redundancy Check (CRC) Mode
            2. 8.3.8.5.3.2 Forward Error Correction (FEC) Mode
          4. 8.3.8.5.4 Initial Lane Alignment
          5. 8.3.8.5.5 Block, Multiblock and Extended Multiblock Alignment Monitoring
        6. 8.3.8.6 Physical Layer
          1. 8.3.8.6.1 SerDes Pre-Emphasis
        7. 8.3.8.7 JESD204C Enable
        8. 8.3.8.8 Multi-Device Synchronization and Deterministic Latency
        9. 8.3.8.9 Operation in Subclass 0 Systems
      9. 8.3.9 Alarm Monitoring
        1. 8.3.9.1 NCO Upset Detection
        2. 8.3.9.2 Clock Upset Detection
        3. 8.3.9.3 FIFO Upset Detection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Dual-Channel Mode
      2. 8.4.2 Single-Channel Mode (DES Mode)
      3. 8.4.3 JESD204C Modes
        1. 8.4.3.1 JESD204C Transport Layer Data Formats
        2. 8.4.3.2 64B/66B Sync Header Stream Configuration
        3. 8.4.3.3 Dual DDC and Redundant Data Mode
      4. 8.4.4 Power-Down Modes
      5. 8.4.5 Test Modes
        1. 8.4.5.1 Serializer Test-Mode Details
        2. 8.4.5.2 PRBS Test Modes
        3. 8.4.5.3 Clock Pattern Mode
        4. 8.4.5.4 Ramp Test Mode
        5. 8.4.5.5 Short and Long Transport Test Mode
          1. 8.4.5.5.1 Short Transport Test Pattern
          2. 8.4.5.5.2 Long Transport Test Pattern
        6. 8.4.5.6 D21.5 Test Mode
        7. 8.4.5.7 K28.5 Test Mode
        8. 8.4.5.8 Repeated ILA Test Mode
        9. 8.4.5.9 Modified RPAT Test Mode
      6. 8.4.6 Calibration Modes and Trimming
        1. 8.4.6.1 Foreground Calibration Mode
        2. 8.4.6.2 Background Calibration Mode
        3. 8.4.6.3 Low-Power Background Calibration (LPBG) Mode
      7. 8.4.7 Offset Calibration
      8. 8.4.8 Trimming
    5. 8.5 Programming
      1. 8.5.1 Using the Serial Interface
        1. 8.5.1.1 SCS
        2. 8.5.1.2 SCLK
        3. 8.5.1.3 SDI
        4. 8.5.1.4 SDO
        5. 8.5.1.5 Streaming Mode
    6. 8.6 SPI_Register_Map Registers
      1. 8.6.1   CONFIG_A Register (Address = 0x0) [reset = 0x30]
        1. Table 60. CONFIG_A Register Field Descriptions
      2. 8.6.2   DEVICE_CONFIG Register (Address = 0x2) [reset = 0x00]
        1. Table 61. DEVICE_CONFIG Register Field Descriptions
      3. 8.6.3   CHIP_TYPE Register (Address = 0x3) [reset = 0x03]
        1. Table 62. CHIP_TYPE Register Field Descriptions
      4. 8.6.4   CHIP_ID Register (Address = 0x4) [reset = 0x0]
        1. Table 63. CHIP_ID Register Field Descriptions
      5. 8.6.5   VENDOR_ID Register (Address = 0xC) [reset = 0x0]
        1. Table 64. VENDOR_ID Register Field Descriptions
      6. 8.6.6   USR0 Register (Address = 0x10) [reset = 0x00]
        1. Table 65. USR0 Register Field Descriptions
      7. 8.6.7   CLK_CTRL0 Register (Address = 0x29) [reset = 0x00]
        1. Table 66. CLK_CTRL0 Register Field Descriptions
      8. 8.6.8   CLK_CTRL1 Register (Address = 0x2A) [reset = 0x00]
        1. Table 67. CLK_CTRL1 Register Field Descriptions
      9. 8.6.9   SYSREF_POS Register (Address = 0x2C) [reset = 0x0]
        1. Table 68. SYSREF_POS Register Field Descriptions
      10. 8.6.10  FS_RANGE_A Register (Address = 0x30) [reset = 0x0]
        1. Table 69. FS_RANGE_A Register Field Descriptions
      11. 8.6.11  FS_RANGE_B Register (Address = 0x32) [reset = 0x0]
        1. Table 70. FS_RANGE_B Register Field Descriptions
      12. 8.6.12  BG_BYPASS Register (Address = 0x38) [reset = 0x00]
        1. Table 71. BG_BYPASS Register Field Descriptions
      13. 8.6.13  TMSTP_CTRL Register (Address = 0x3B) [reset = 0x00]
        1. Table 72. TMSTP_CTRL Register Field Descriptions
      14. 8.6.14  SER_PE Register (Address = 0x48) [reset = 0x00]
        1. Table 73. SER_PE Register Field Descriptions
      15. 8.6.15  INPUT_MUX Register (Address = 0x60) [reset = 0x01]
        1. Table 74. INPUT_MUX Register Field Descriptions
      16. 8.6.16  CAL_EN Register (Address = 0x61) [reset = 0x01]
        1. Table 75. CAL_EN Register Field Descriptions
      17. 8.6.17  CAL_CFG0 Register (Address = 0x62) [reset = 0x01]
        1. Table 76. CAL_CFG0 Register Field Descriptions
      18. 8.6.18  CAL_AVG Register (Address = 0x68) [reset = 0x61]
        1. Table 77. CAL_AVG Register Field Descriptions
      19. 8.6.19  CAL_STATUS Register (Address = 0x6A) [reset = 0x0]
        1. Table 78. CAL_STATUS Register Field Descriptions
      20. 8.6.20  CAL_PIN_CFG Register (Address = 0x6B) [reset = 0x00]
        1. Table 79. CAL_PIN_CFG Register Field Descriptions
      21. 8.6.21  CAL_SOFT_TRIG Register (Address = 0x6C) [reset = 0x01]
        1. Table 80. CAL_SOFT_TRIG Register Field Descriptions
      22. 8.6.22  CAL_LP Register (Address = 0x6E) [reset = 0x88]
        1. Table 81. CAL_LP Register Field Descriptions
      23. 8.6.23  CAL_DATA_EN Register (Address = 0x70) [reset = 0x00]
        1. Table 82. CAL_DATA_EN Register Field Descriptions
      24. 8.6.24  CAL_DATA Register (Address = 0x71) [reset = 0x0]
        1. Table 83. CAL_DATA Register Field Descriptions
      25. 8.6.25  GAIN_TRIM_A Register (Address = 0x7A) [reset = 0x0]
        1. Table 84. GAIN_TRIM_A Register Field Descriptions
      26. 8.6.26  GAIN_TRIM_B Register (Address = 0x7B) [reset = 0x0]
        1. Table 85. GAIN_TRIM_B Register Field Descriptions
      27. 8.6.27  BG_TRIM Register (Address = 0x7C) [reset = 0x0]
        1. Table 86. BG_TRIM Register Field Descriptions
      28. 8.6.28  RTRIM_A Register (Address = 0x7E) [reset = 0x0]
        1. Table 87. RTRIM_A Register Field Descriptions
      29. 8.6.29  RTRIM_B Register (Address = 0x7F) [reset = 0x0]
        1. Table 88. RTRIM_B Register Field Descriptions
      30. 8.6.30  ADC_DITH Register (Address = 0x9D) [reset = 0x0]
        1. Table 89. ADC_DITH Register Field Descriptions
      31. 8.6.31  B0_TIME_0 Register (Address = 0x102) [reset = 0x0]
        1. Table 90. B0_TIME_0 Register Field Descriptions
      32. 8.6.32  B0_TIME_90 Register (Address = 0x103) [reset = 0x0]
        1. Table 91. B0_TIME_90 Register Field Descriptions
      33. 8.6.33  B1_TIME_0 Register (Address = 0x112) [reset = 0x0]
        1. Table 92. B1_TIME_0 Register Field Descriptions
      34. 8.6.34  B1_TIME_90 Register (Address = 0x113) [reset = 0x0]
        1. Table 93. B1_TIME_90 Register Field Descriptions
      35. 8.6.35  B4_TIME_0 Register (Address = 0x142) [reset = 0x0]
        1. Table 94. B4_TIME_0 Register Field Descriptions
      36. 8.6.36  B5_TIME_0 Register (Address = 0x152) [reset = 0x0]
        1. Table 95. B5_TIME_0 Register Field Descriptions
      37. 8.6.37  LSB_CTRL Register (Address = 0x160) [reset = 0x00]
        1. Table 96. LSB_CTRL Register Field Descriptions
      38. 8.6.38  JESD_EN Register (Address = 0x200) [reset = 0x01]
        1. Table 97. JESD_EN Register Field Descriptions
      39. 8.6.39  JMODE Register (Address = 0x201) [reset = 0x02]
        1. Table 98. JMODE Register Field Descriptions
      40. 8.6.40  KM1 Register (Address = 0x202) [reset = 0x1]
        1. Table 99. KM1 Register Field Descriptions
      41. 8.6.41  JSYNC_N Register (Address = 0x203) [reset = 0x01]
        1. Table 100. JSYNC_N Register Field Descriptions
      42. 8.6.42  JCTRL Register (Address = 0x204) [reset = 0x02]
        1. Table 101. JCTRL Register Field Descriptions
      43. 8.6.43  JTEST Register (Address = 0x205) [reset = 0x00]
        1. Table 102. JTEST Register Field Descriptions
      44. 8.6.44  DID Register (Address = 0x206) [reset = 0x00]
        1. Table 103. DID Register Field Descriptions
      45. 8.6.45  FCHAR Register (Address = 0x207) [reset = 0x00]
        1. Table 104. FCHAR Register Field Descriptions
      46. 8.6.46  JESD_STATUS Register (Address = 0x208) [reset = 0x0]
        1. Table 105. JESD_STATUS Register Field Descriptions
      47. 8.6.47  PD_CH Register (Address = 0x209) [reset = 0x00]
        1. Table 106. PD_CH Register Field Descriptions
      48. 8.6.48  JEXTRA_A Register (Address = 0x20A) [reset = 0x00]
        1. Table 107. JEXTRA_A Register Field Descriptions
      49. 8.6.49  JEXTRA_B Register (Address = 0x20B) [reset = 0x00]
        1. Table 108. JEXTRA_B Register Field Descriptions
      50. 8.6.50  SHMODE Register (Address = 0x20F) [reset = 0x00]
        1. Table 109. SHMODE Register Field Descriptions
      51. 8.6.51  DDC_CFG Register (Address = 0x210) [reset = 0x00]
        1. Table 110. DDC_CFG Register Field Descriptions
      52. 8.6.52  OVR_T0 Register (Address = 0x211) [reset = 0x0]
        1. Table 111. OVR_T0 Register Field Descriptions
      53. 8.6.53  OVR_T1 Register (Address = 0x212) [reset = 0x0]
        1. Table 112. OVR_T1 Register Field Descriptions
      54. 8.6.54  OVR_CFG Register (Address = 0x213) [reset = 0x07]
        1. Table 113. OVR_CFG Register Field Descriptions
      55. 8.6.55  CMODE Register (Address = 0x214) [reset = 0x00]
        1. Table 114. CMODE Register Field Descriptions
      56. 8.6.56  CSEL Register (Address = 0x215) [reset = 0x00]
        1. Table 115. CSEL Register Field Descriptions
      57. 8.6.57  DIG_BIND Register (Address = 0x216) [reset = 0x02]
        1. Table 116. DIG_BIND Register Field Descriptions
      58. 8.6.58  NCO_RDIV Register (Address = 0x217) [reset = 0x0000]
        1. Table 117. NCO_RDIV Register Field Descriptions
      59. 8.6.59  NCO_SYNC Register (Address = 0x219) [reset = 0x02]
        1. Table 118. NCO_SYNC Register Field Descriptions
      60. 8.6.60  FREQA0 Register (Address = 0x220) [reset = 0x0]
        1. Table 119. FREQA0 Register Field Descriptions
      61. 8.6.61  PHASEA0 Register (Address = 0x224) [reset = 0x0000]
        1. Table 120. PHASEA0 Register Field Descriptions
      62. 8.6.62  FREQA1 Register (Address = 0x228) [reset = 0x0]
        1. Table 121. FREQA1 Register Field Descriptions
      63. 8.6.63  PHASEA1 Register (Address = 0x22C) [reset = 0x0000]
        1. Table 122. PHASEA1 Register Field Descriptions
      64. 8.6.64  FREQA2 Register (Address = 0x230) [reset = 0x0]
        1. Table 123. FREQA2 Register Field Descriptions
      65. 8.6.65  PHASEA2 Register (Address = 0x234) [reset = 0x0000]
        1. Table 124. PHASEA2 Register Field Descriptions
      66. 8.6.66  FREQA3 Register (Address = 0x238) [reset = 0x0]
        1. Table 125. FREQA3 Register Field Descriptions
      67. 8.6.67  PHASEA3 Register (Address = 0x23C) [reset = 0x0000]
        1. Table 126. PHASEA3 Register Field Descriptions
      68. 8.6.68  FREQB0 Register (Address = 0x240) [reset = 0x0]
        1. Table 127. FREQB0 Register Field Descriptions
      69. 8.6.69  PHASEB0 Register (Address = 0x244) [reset = 0x0000]
        1. Table 128. PHASEB0 Register Field Descriptions
      70. 8.6.70  FREQB1 Register (Address = 0x248) [reset = 0x0]
        1. Table 129. FREQB1 Register Field Descriptions
      71. 8.6.71  PHASEB1 Register (Address = 0x24C) [reset = 0x0000]
        1. Table 130. PHASEB1 Register Field Descriptions
      72. 8.6.72  FREQB2 Register (Address = 0x250) [reset = 0x0]
        1. Table 131. FREQB2 Register Field Descriptions
      73. 8.6.73  PHASEB2 Register (Address = 0x254) [reset = 0x0000]
        1. Table 132. PHASEB2 Register Field Descriptions
      74. 8.6.74  FREQB3 Register (Address = 0x258) [reset = 0x0]
        1. Table 133. FREQB3 Register Field Descriptions
      75. 8.6.75  PHASEB3 Register (Address = 0x25C) [reset = 0x0000]
        1. Table 134. PHASEB3 Register Field Descriptions
      76. 8.6.76  SPIN_ID Register (Address = 0x297) [reset = 0x0]
        1. Table 135. SPIN_ID Register Field Descriptions
      77. 8.6.77  SRC_EN Register (Address = 0x2B0) [reset = 0x00]
        1. Table 136. SRC_EN Register Field Descriptions
      78. 8.6.78  SRC_CFG Register (Address = 0x2B1) [reset = 0x05]
        1. Table 137. SRC_CFG Register Field Descriptions
      79. 8.6.79  SRC_STATUS Register (Address = 0x2B2) [reset = 0x0]
        1. Table 138. SRC_STATUS Register Field Descriptions
      80. 8.6.80  TAD Register (Address = 0x2B5) [reset = 0x00]
        1. Table 139. TAD Register Field Descriptions
      81. 8.6.81  TAD_RAMP Register (Address = 0x2B8) [reset = 0x00]
        1. Table 140. TAD_RAMP Register Field Descriptions
      82. 8.6.82  ALARM Register (Address = 0x2C0) [reset = 0x0]
        1. Table 141. ALARM Register Field Descriptions
      83. 8.6.83  ALM_STATUS Register (Address = 0x2C1) [reset = 0x3]
        1. Table 142. ALM_STATUS Register Field Descriptions
      84. 8.6.84  ALM_MASK Register (Address = 0x2C2) [reset = 0x3]
        1. Table 143. ALM_MASK Register Field Descriptions
      85. 8.6.85  FIFO_LANE_ALM Register (Address = 0x2C4) [reset = 0x0]
        1. Table 144. FIFO_LANE_ALM Register Field Descriptions
      86. 8.6.86  TADJ_A Register (Address = 0x310) [reset = 0x0]
        1. Table 145. TADJ_A Register Field Descriptions
      87. 8.6.87  TADJ_B Register (Address = 0x313) [reset = 0x0]
        1. Table 146. TADJ_B Register Field Descriptions
      88. 8.6.88  TADJ_A_FG90_VINA Register (Address = 0x314) [reset = 0x0]
        1. Table 147. TADJ_A_FG90_VINA Register Field Descriptions
      89. 8.6.89  TADJ_B_FG0_VINA Register (Address = 0x315) [reset = 0x0]
        1. Table 148. TADJ_B_FG0_VINA Register Field Descriptions
      90. 8.6.90  TADJ_A_FG90_VINB Register (Address = 0x31A) [reset = 0x0]
        1. Table 149. TADJ_A_FG90_VINB Register Field Descriptions
      91. 8.6.91  TADJ_B_FG0_VINB Register (Address = 0x31B) [reset = 0x0]
        1. Table 150. TADJ_B_FG0_VINB Register Field Descriptions
      92. 8.6.92  OADJ_A_FG0_VINA Register (Address = 0x344) [reset = 0x0]
        1. Table 151. OADJ_A_FG0_VINA Register Field Descriptions
      93. 8.6.93  OADJ_A_FG0_VINB Register (Address = 0x346) [reset = 0x0]
        1. Table 152. OADJ_A_FG0_VINB Register Field Descriptions
      94. 8.6.94  OADJ_A_FG90_VINA Register (Address = 0x348) [reset = 0x0]
        1. Table 153. OADJ_A_FG90_VINA Register Field Descriptions
      95. 8.6.95  OADJ_A_FG90_VINB Register (Address = 0x34A) [reset = 0x0]
        1. Table 154. OADJ_A_FG90_VINB Register Field Descriptions
      96. 8.6.96  OADJ_B_FG0_VINA Register (Address = 0x34C) [reset = 0x0]
        1. Table 155. OADJ_B_FG0_VINA Register Field Descriptions
      97. 8.6.97  OADJ_B_FG0_VINB Register (Address = 0x34E) [reset = 0x0]
        1. Table 156. OADJ_B_FG0_VINB Register Field Descriptions
      98. 8.6.98  GAIN_B0 Register (Address = 0x360) [reset = 0x0]
        1. Table 157. GAIN_B0 Register Field Descriptions
      99. 8.6.99  GAIN_B1 Register (Address = 0x361) [reset = 0x0]
        1. Table 158. GAIN_B1 Register Field Descriptions
      100. 8.6.100 GAIN_B4 Register (Address = 0x364) [reset = 0x0]
        1. Table 159. GAIN_B4 Register Field Descriptions
      101. 8.6.101 GAIN_B5 Register (Address = 0x365) [reset = 0x0]
        1. Table 160. GAIN_B5 Register Field Descriptions
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Wideband RF Sampling Receiver
        1. 9.2.1.1 Design Requirements
          1. 9.2.1.1.1 Input Signal Path
          2. 9.2.1.1.2 Clocking
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Calculating Values of AC-Coupling Capacitors
      2. 9.2.2 Reconfigurable Dual-Channel 5-GSPS or Single-Channel 10-Gsps Oscilloscope
        1. 9.2.2.1 Design Requirements
          1. 9.2.2.1.1 Input Signal Path
          2. 9.2.2.1.2 Clocking
          3. 9.2.2.1.3 ADC12DJ5200RF
    3. 9.3 Initialization Set Up
  10. 10Power Supply Recommendations
    1. 10.1 Power Sequencing
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 デバイス・サポート
      1. 12.1.1 デベロッパー・ネットワークの製品に関する免責事項
      2. 12.1.2 開発サポート
    2. 12.2 ドキュメントのサポート
      1. 12.2.1 関連資料
    3. 12.3 ドキュメントの更新通知を受け取る方法
    4. 12.4 コミュニティ・リソース
    5. 12.5 商標
    6. 12.6 静電気放電に関する注意事項
    7. 12.7 Glossary
  13. 13メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ(パッケージ|ピン)
サーマルパッド・メカニカル・データ
発注情報

SYSREF Position Detector and Sampling Position Selection (SYSREF Windowing)

The SYSREF windowing block is used to first detect the position of SYSREF relative to the CLK± rising edge and then to select a desired SYSREF sampling instance, which is a delay version of CLK±, to maximize setup and hold timing margins. In many cases a single SYSREF sampling position (SYSREF_SEL) is sufficient to meet timing for all systems (device-to-device variation) and conditions (temperature and voltage variations). However, this feature can also be used by the system to expand the timing window by tracking the movement of SYSREF as operating conditions change or to remove system-to-system variation at production test by finding a unique optimal value at nominal conditions for each system.

This section describes proper usage of the SYSREF windowing block. First, apply the device clock and SYSREF to the device. The location of SYSREF relative to the device clock cycle is determined and stored in the SYSREF_POS bits of the SYSREF capture position register. ADC12DJ5200RF must see at least 3 rising edges of SYSREF before the SYSREF_POS output is valid. Each bit of SYSREF_POS represents a potential SYSREF sampling position. If a bit in SYSREF_POS is set to 1, then the corresponding SYSREF sampling position has a potential setup or hold violation. Upon determining the valid SYSREF sampling positions (the positions of SYSREF_POS that are set to 0) the desired sampling position can be chosen by setting SYSREF_SEL in the clock control register 0 to the value corresponding to that SYSREF_POS position. In general, the middle sampling position between two setup and hold instances is chosen. Ideally, SYSREF_POS and SYSREF_SEL are performed at the nominal operating conditions of the system (temperature and supply voltage) to provide maximum margin for operating condition variations. This process can be performed at final test and the optimal SYSREF_SEL setting can be stored for use at every system power up. Further, SYSREF_POS can be used to characterize the skew between CLK± and SYSREF± over operating conditions for a system by sweeping the system temperature and supply voltages. For systems that have large variations in CLK± to SYSREF± skew, this characterization can be used to track the optimal SYSREF sampling position as system operating conditions change. In general, a single value can be found that meets timing over all conditions for well-matched systems, such as those where CLK± and SYSREF± come from a single clocking device.

NOTE

SYSREF_SEL must be set to 0 when using automatic SYSREF calibration; see the Automatic SYSREF Calibration section.

The step size between each SYSREF_POS sampling position can be adjusted using SYSREF_ZOOM. When SYSREF_ZOOM is set to 0, the delay steps are coarser. When SYSREF_ZOOM is set to 1, the delay steps are finer. See the Switching Characteristics table for delay step sizes when SYSREF_ZOOM is enabled and disabled. In general, SYSREF_ZOOM is recommended to always be used (SYSREF_ZOOM = 1) unless a transition region (defined by 1's in SYSREF_POS) is not observed, which can be the case for low clock rates. Bits 0 and 23 of SYSREF_POS are always be set to 1 because there is insufficient information to determine if these settings are close to a timing violation, although the actual valid window can extend beyond these sampling positions. The value programmed into SYSREF_SEL is the decimal number representing the desired bit location in SYSREF_POS. Table 7 lists some example SYSREF_POS readings and the optimal SYSREF_SEL settings. Although 24 sampling positions are provided by the SYSREF_POS status register, SYSREF_SEL only allows selection of the first 16 sampling positions, corresponding to SYSREF_POS bits 0 to 15. The additional SYSREF_POS status bits are intended only to provide additional knowledge of the SYSREF valid window. In general, lower values of SYSREF_SEL are selected because of delay variation over supply voltage, however in the fourth example a value of 15 provides additional margin and can be selected instead.

Table 7. Examples of SYSREF_POS Readings and SYSREF_SEL Selections

SYSREF_POS[23:0] OPTIMAL SYSREF_SEL SETTING
0x02E[7:0]
(Largest Delay)
0x02D[7:0](1) 0x02C[7:0](1)
(Smallest Delay)
b10000000 b01100000 b00011001 8 or 9
b10011000 b00000000 b00110001 12
b10000000 b01100000 b00000001 6 or 7
b10000000 b00000011 b00000001 4 or 15
b10001100 b01100011 b00011001 6
Red coloration indicates the bits that are selected, as given in the last column of this table.