您好、TI。
我们正在尝试使用嵌套零延迟双环路模式中的 LMK04828获得以下输出。
- SDCLKout3:625MHz (DCLK)
- SDCLKout5:10MHz (SYSREF)
- DCLKout6:250MHz (DCLK)
- SDCLKout9:10MHz (SYSREF)
配置为器件时钟(DCLK)的 SDCLKout3和 DCLKout6输出正常工作(在实验中检查)。 另一方面、我们在配置为 SYSREF 时钟的 SDCLKout5和 SDCLKout9输出上没有获得任何输出。
我们使用连续 SYSREF 模式。
随附了我们使用的配置序列和简化的 LMK04828方框图。
请您看一下配置、并就我们可能发生的错误向我们提供一些建议吗?
此致、
O.
/***********************************/ /* 10M-250M-650M-RYT-v1.0.1 */ /***********************************/ /********************/ /* System functions */ /********************/ 0x0000 0x80 // Soft reset, 3-wire mode enabled (default) 0x0002 0x00 /*****************************************************************/ /* Device Clock and SYSREF Clock Output Controls (0x100 - 0x137) */ /*****************************************************************/ // DCLKout0 and SDCLKout1 0x0100 0x02 // DCLK Divider: 2; Input/Output Drive Level Off; 0x0101 0x55 0x0103 0x00 0x0104 0x00 // SDCLK Source: DCLK; 0x0105 0x00 0x0106 0xFB // Group Powerdown: On; Powerdown SDCLK: On; 0x0107 0x00 // SDCLK Format: Powerdown; DCLK Format: Powerdown; // DCLKout2 and SDCLKout3 0x0108 0x04 // DCLK Divider: 4; Input/Output Drive Level Off; 0x0109 0x55 0x010B 0x00 0x010C 0x00 // SDCLK Source: DCLK; 0x010D 0x00 0x010E 0xF2 // Group Powerdown: Off; Powerdown SDCLK: Off; 0x010F 0x10 // SDCLK Format: LVDS; DCLK Format: Powerdown; // DCLKout4 and SDCLKout5 0x0110 0x08 // DCLK Divider: 4; Input/Output Drive Level Off; 0x0111 0x55 0x0113 0x00 0x0114 0x20 // SDCLK Source: SYSREF; 0x0115 0x00 0x0116 0xF2 // Group Powerdown: Off; Powerdown SDCLK: Off; 0x0117 0x10 // SDCLK Format: LVDS; DCLK Format: Powerdown; // DCLKout6 and SDCLKout7 0x0118 0x0A // DCLK Divider: 10; Input/Output Drive Level Off; 0x0119 0x55 0x011B 0x00 0x011C 0x00 // SDCLK Source: DCLK; 0x011D 0x00 0x011E 0xF2 // Group Powerdown: Off; Powerdown SDCLK: Off; 0x011F 0x01 // SDCLK Format: Powerdown; DCLK Format: LVDS; // DCLKout8 and SDCLKout9 0x0120 0x08 // DCLK Divider: 8; Input/Output Drive Level Off; 0x0121 0x55 0x0123 0x00 0x0124 0x20 // SDCLK Source: SYSREF; 0x0125 0x00 0x0126 0xF2 // Group Powerdown: Off; Powerdown SDCLK: Off; 0x0127 0x10 // SDCLK Format: LVDS; DCLK Format: Powerdown; // DCLKout10 and SDCLKout11 0x0128 0x08 // DCLK Divider: 8; Input/Output Drive Level Off; 0x0129 0x55 0x012B 0x00 0x012C 0x00 // SDCLK Source: DCLK; 0x012D 0x00 0x012E 0xFB // Group Powerdown: On; Powerdown SDCLK: On; 0x012F 0x00 // SDCLK Format: Powerdown; DCLK Format: Powerdown; // DCLKout12 and SDCLKout13 0x0130 0x02 // DCLK Divider: 2; Input/Output Drive Level Off; 0x0131 0x55 0x0133 0x00 0x0134 0x00 // SDCLK Source: DCLK; 0x0135 0x00 0x0136 0xFB // Group Powerdown: On; Powerdown SDCLK: On; 0x0137 0x00 // SDCLK Format: Powerdown; DCLK Format: Powerdown; /**************************************************/ /* SYSREF, SYNC and Device Config (0x138 - 0x145) */ /**************************************************/ 0x0138 0x00 // OSCout Format: Powerdown (CLKin2); PLL2 VCO: VCO_0 ; 0x0139 0x00 // SYSREF_MUX = 0 (Normal SYNC) 0x013A 0x00 // SYSREF Divider High: 0 0x013B 0xFA // SYSREF Divider Low: 0xFA=250 (2500MHz/250=10 MHz) 0x013C 0x00 0x013D 0x00 0x013E 0x03 // SYSREF Pulse count: 8 pulses 0x013F 0x09 // Feedback Mux: Enabled; Feedback Mux Source: DCLKout6; PLL1 N Mux Source: Feedback Mux 0x0140 0x01 // SYSREF Global Powrdown Bit: Off ; SYSREF Powerdown: Off; SYSREF DDLY Powerdown: Off; SYSREF Pulse Generator Powerdown: On 0x0141 0x00 0x0142 0x00 0x0143 0x11 // SYNC_MODE = 1: SYNC event generated from SYNC pin, SYNC_POL = 0 0x0144 0x00 // Able SYSREF divider and clocks dividers from becoming synchronized during a SYNC event. 0x0145 0x7F // Fixed Register: Always write 0x7F (127). /*********************************/ /* CLKin Control (0x146 - 0x149) */ /*********************************/ 0x0146 0x28 // CLKin0 and CLKin2 enabled to be used dring auto-switching; CLKin0/1/2_TYPE = Bipolar; 0x0147 0x2A // CLKin0_OUT_MUX = 0x02 (PLL1); CLKin1_OUT_MUX = 0x02 (PLL1); CLKin_SEL_MODE = 0x02 (CLKin2 Manual); 0x0148 0x02 // Configure CLKin_SEL0 as an input (with pull down); 0x0149 0x42 // Configure CLKin_SEL1 as an input (with pull down); SDIO pin is open drain during SPI readback in 3 wire mode; /****************************/ /* RESET_MUX and RESET_TYPE */ /****************************/ 0x014A 0x02 // Configure RESET pin as an input. /****************************/ /* Holdover (0x14B - 0x152) */ /****************************/ 0x014B 0x02 // LOS_EN = '0'; TRACK_EN = '0'; MAN_DAC_EN = '0'; MAN_DAC = 512; 0x014C 0x00 // 0x014D 0x00 // 0x014E 0xC0 // DAC_CLK_MULT = 0x03 (16384); DAC_CLK_MULT = 0x00 (4); 0x014F 0x7F // DAC_CLK_CNTR = 127; 0x0150 0x00 // HOLDOVER_EN = '0'; HOLDOVER_HITLESS_SWITCH = '0' 0x0151 0x02 // HOLDOVER_DLD_CNT = 512 0x0152 0x00 // HOLDOVER_DLD_CNT = 512 /**************************************/ /* PLL1 Configuration (0x153 - 0x15F) */ /**************************************/ 0x0153 0x00 // CLKin0_R = 2 0x0154 0x02 // CLKin0_R = 2 0x0155 0x00 // CLKin1_R = 120 0x0156 0x78 // CLKin1_R = 120 0x0157 0x00 // CLKin2_R = 2 0x0158 0x02 // CLKin2_R = 2 0x0159 0x00 // PLL1_N(13:0) = 50 0x015A 0x32 // PLL1_N(13:0) = 50 0x015B 0xD4 // CP Gain=0x04(450uA); PLL1 CPout1: Active (Not TRI-STATED); PLL1_WND_SIZE=0x03(43ns) 0x015C 0x20 // PLL1_DLD_CNT = 8192; 0x015D 0x00 // PLL1_DLD_CNT = 8192; 0x015E 0x00 // 0x015F 0x0B // Status_LD1. PLL1_LD_TYPE = 0x03 (Output (push-pull)); PLL1_LD_MUX = 0x01 (PLL1 DLD); /**************************************/ /* PLL2 Configuration (0x160 - 0x165) */ /**************************************/ 0x0160 0x00 // PLL2_R = 10 0x0161 0x0A // PLL2_R = 10 0x0162 0x44 // 0x44 -> Freq Doubler: Disabled; OSCin FREQ 67MHz-127MHz; PLL2_P = 2; 0x0163 0x00 0x0164 0x00 // PLL2_N_CAL = 25 0x0165 0x19 // PLL2_N_CAL = 25 // Fixed registers 0x0171 0xAA // Program register 0x171 to 0xAA 0x0172 0x02 // Program register 0x172 to 0x02 // Programming registers 0x17C and 0x17D 0x017C 0x15 // OPT_REG_1. 24 for LMK04826; 21 for LMK04828 and LMK04821" 0x017D 0x33 // OPT_REG_2. 119 for LMK04826; 51 for LMK04828 and LMK04821" /**************************************/ /* PLL2 Configuration (0x166 - 0x16E) */ /**************************************/ 0x0166 0x00 // PLL2_N(17:0) = 100 0x0167 0x00 // PLL2_N(17:0) = 100 0x0168 0x64 // PLL2_N(17:0) = 100 0x0169 0x59 0x016A 0x20 0x016B 0x00 0x016C 0x00 0x016D 0x00 0x016E 0x13 // Status_LD2. PLL2_LD_TYPE = 0x03 (Output (push-pull)); PLL2_LD_MUX = 0x02 (PLL2 DLD); /***************************************************/ /* Sync Dividers Sequence and SYSREF Configuration */ /***************************************************/ // Configure sync ciruit to sync dividers: 0x0139 0x00 // SYSREF_CLKin0_MUX=0b, SYSREF_MUX=0d (Normal SYNC) 0x0143 0x11 // SYNC_EN=1b and SYNC_MODE=1d SYNC event generated from SYNC pin 0x0144 0x00 // Configure SYSREF and Device clock to be synchronized during a SYNC event // Generate a SYNC event 0x0143 0x31 // Toggle SYNC_POL to generate a SYNC event 0x0143 0x11 // Toggle SYNC_POL to generate a SYNC event // Set user desired SYSREF configuration 0x0144 0xFF // Avoid dividers to be synced by SYNC Pin 0x0143 0x00 // Prevents SYNC pin from generating a SYNC event. 0x0139 0x03 // SYSREF_MUX=3d (SYSREF continouos)
