时钟和计时论坛 - 最近的话题

LMKDB1108: LMKDB1108 無法正常輸出

Chou Howard — Mon, 14 Sep 2026 08:26:06 GMT

Part Number: LMKDB1108

我司是震盪器廠家目前伺服器廠家指定通過 LMKDB1108 進行測試 Phase Noise

我司以購買此EVM版在使用時採用 156.25 HCSL震盪器做為板子的輸入端軟件採用

TICS PRO V1.7.10 ; 目前發現裝完軟件板子依舊無法正常工作

能幫忙確認會是那些問題?

LMK04832: LMK04832在无时钟源输入时存在异常时钟输出。

Jia Tan — Sun, 13 Sep 2026 11:08:54 GMT

Part Number: LMK04832

LMK04832的CLKin1接单端100M的外部时钟源，经过内部倍频输出400M的时钟。此外OSCin也接了一个100M_LVDS晶振，用于备用。LMK04832的配置如下图所示，启用的是CLKin1通道。

测试时发现，当CLKin1的外部时钟源漏接时，400M输出链路上可检测到一个403M的时钟，且幅度正常。怀疑是100M晶振的时钟信号耦合到了CLKin1通道上，将100M晶振的输出通道断掉，测得04832输出了一个396M的时钟。进一步将晶振的电源断掉，测得04832输出了一个376M的时钟。

目前问题还未解决，请协助分析。

LMK00334: LMK00334RTVT 时钟BUF 无输出电压 CLKOUT 一直为3.3V (如下图)

Yanlin Shi — Wed, 09 Sep 2026 11:31:12 GMT

Part Number: LMK00334

初步晶振输出到U30的 PIN 14 和 PIN 15 ，示波器单端测，Vmin = 1.024V ,Vmax = 1.403V ,Vpp= 379mV 的 100MHz 波形，电源VDD_CLK_3.3V 实际测量为3.3V ，目前 4 CH CLKOUT 无输出电压管脚电压一直保持在3.3V ，

麻烦帮忙分析原理图是否存在问题，谢谢 .

LMK04832: LMK04832 完全工作不起来，而换成LMK04828没问题

HJK — Fri, 04 Sep 2026 09:18:05 GMT

Part Number: LMK04832
Other Parts Discussed in Thread: LMK04828, , TXB0108

LMK04832上电直接读芯片ID寄存器没反应，而换成LMK04828有反应且正确
重新更换新的LMK04832也是没反应
独看LMK04828的供电电流3.3V/0.38A，但是LMK04832的电流很低3.3V/0.057A测试过每个电源引脚电压都是有的，而且焊接没问题
为什么LMK04832和04828在同样的板上/设计上表现会有区别？目前用的都是3线SPI，LMK04832/LMK04828都是使用三线，两张板子都是这样，LMK04832工作不起来，芯片电流也比较低3.3V/0.057A，而更换成LMK04828工作正常电流3.3V/0.38A，我们也没配置POWER-DOWN之类的，反正LMK04832在我们板上就是工作不正常，我们怀疑不清楚是什么导致LMK04832的电流很小，从而SPI也不工作。有没什么可能影响或者排查的方向，我们检查过焊接，也尝试过新采购片子LMK04832 还是没效果

LMK04832: LMK04832如何实现跨板时钟同频同相

SHUNDA ZHONG — Mon, 31 Aug 2026 12:30:19 GMT

Part Number: LMK04832

您好：

我们在使用LMK04832设计一个多片AD同步采集系统时，遇到了相位差不固定问题，现在有两个问题想确认一下：

1、在输入时钟同源相参时钟的情况下，多片LMK04832的输出时钟在上下电初始化过程中，是否会存在相位偏差，且偏移量是输入时钟的整数倍。例如：两片04832输入400MHz的时钟，输出10MHz时钟的边沿之间会存在相位偏移，偏移量是**输入时钟周期的整数倍**（400MHz 周期 = 2.5ns），相位差范围 0~100ns（10MHz 周期）之间随机。

2、如果要做到多片LMK04832同时使用时，输出的时钟相位差固定，是否需要将所有芯片的SYNC管脚连接到一起，并输入一个统一的触发信号？请推荐多片LMK04832同时使用时，输出时钟相位偏差固定的硬件设计方案（原理图或框图）。

祝好！

LMX2594: LMX2594 Automatic ramping mode信号输出问题

lizeng dong — Fri, 28 Aug 2026 09:40:32 GMT

Part Number: LMX2594

您好！
我们需要使用LMX2594生成10700MHz~11700MHz和11800MHz~12800MHz的线性扫频，现在是利用两颗LMX2954各自负责一个频段的线性扫描。目前我们进行的测试都是在10700MHz~11700MHz频段，我们想要的是在这个频段内任意设置带宽(1MHz~1000MHz)输出线性扫频。现在我测试了100MHz的带宽，输出结果基本满足。在测试200MHz带宽时测试了很多参数(参数时使用TICS Pro工具生成)，都会出现线性扫频扫不出一段高频率的信号。以下是我的配置截图和测试结果截图。

测试1：10700MHz~10800MHz

测试2：10600MHz~10800MHz

示波器监测的是芯片的35脚Vtune的电压

就上述现象，有以下几点需要贵司确认。

①.在我配置中是否存在不合理的参数，影响是什么？需要怎么解决？

②.关于带宽200M及以上需要怎么配置？是否有需要手动修改的寄存器参数，还是使用TICS Pro工具配置就能完成业务？

③.扫频信号是从10700MHz~11700MHz，在扫描时会选择不同的VCO，这样VCO的校准是否不可避免？实际扫频持续时间就会和设置扫频持续就会相差很多？我也试过在1000MHz带宽时把Threshole参数设置为1000，但是实际扫频输出和预想相去甚远，看起来像是点频。

我测试是使用自己的硬件，没有官方硬件。望尽快回复，谢谢！

LMK04828-EP: LMK04828 :Multi-Board clock Synchronization

xue xiaoman — Sat, 22 Aug 2026 01:44:49 GMT

Part Number: LMK04828-EP
Other Parts Discussed in Thread: LMK04828

Hi ,sir

I am working on a custom hardware utilizing the LMK04828. My goal is to achieve Multi-clock Sync across multiple boards.

The hardware clocking architecture is centered around the LMK04828 jitter cleaner/clock distributor. The current configuration is as follows:

the first clock board: A 100MHz clock is provided to the OSCin pin of the LMK04828 to achive the 250MHz clock and 7.8125MHz sysref to the second clock board.
the second clock board: the 250MHz clock is provided to the CLKin1 pin of the LMK04828，while 7.8125MHz sysref is provided to the CLKin0 pin of the LMK04828, this LMK04828 is used as clock distributor to produce more DCLKOUTs (250MHz) and SDCLKOUTs (7.8125MHz)。
question：we only provided 250MHz clock to the CLKin1 pin of the second clock board LMK04828 ,the DCLKOUTs are 250MHz, while SDCLKOUTs are spurs.
But when we provided 250MHz clock to the CLKin1 and 7.8125MHz sysref to the CLKin0 pin of the LMK04828， the SDCLKOUTs work well。
We don't know why SDCLKOUTs are spurs when we only provided 250MHz clock to the CLKin1 pin。Can you give me some advice?

LMX1205: LMX1205寄存器配置，配置顺序

?? ? — Tue, 04 Aug 2026 02:23:04 GMT

Part Number: LMX1205

你好，我在使用LMX1205芯片时遇到一些问题，我们没有使用评估板，使用的单独的芯片，通过SPI来控制,我按以下步骤初始化芯片，没有输出我需要的频率，但寄存器回读是我写进去的值。是否有什么特殊的寄存器需要配置？或者特殊的写入顺序？
以下是我的配置步骤：
1：上电后软件复位：
LMX1205_Write_Registers(0x00,0x0001);
Delay_us(5000);
LMX1205_Write_Registers(0x00,0x0000);
Delay_us(5000);
2：降序写入寄存器表，该表由TICS_PRO软件生成：

0x4D0000,
0x370000,
0x360000,
0x2D2ABF,
0x2C7707,
0x2B7707,
0x2A76F3,
0x2978F3,
0x2878E1,
0x2778E1,
0x250000,
0x248947,
0x200000,
0x1F0000,
0x1E0000,
0x1D0000,
0x1B661A,
0x1A00D0,
0x1901FF,
0x1801FF,
0x1701FF,
0x1601FF,
0x1501FF,
0x14C051,
0x130004,
0x120000,
0x110004,
0x100030,
0x0F0001,
0x0E00C9,
0x0D002B,
0x0C002B,
0x0B5CA9,
0x0A5CA9,
0x095CA9,
0x085CA9,
0x07000D,
0x06000D,
0x05000D,
0x04000D,
0x030000,
0x0201FF,
0x01001B,
0x000000

3：写入寄存器（ DEV_IOPT_CTRL字段）：0x370006
以下是我的软件配置：

LMK04832: LMK04832可以通过三线SPI写入数据，但无法回读是什么原因？

SHUNDA ZHONG — Thu, 30 Jul 2026 12:22:29 GMT

Part Number: LMK04832

您好：

FPGA芯片（IO为1.2V）经过电平转换芯片（NLSX5014MUTAG）后由三线SPI配置加载LMK04832（3.3V供电），LMK04832可以正常加载且时钟也正常输出，但是三线SPI却无法回读LMK04832信息，请问是什么原因呢？

LMX2594EVM: RF output impdedance?

Jifei Chen — Thu, 30 Jul 2026 07:47:51 GMT

Part Number: LMX2594EVM
Other Parts Discussed in Thread: LMX2594

Hello,

One month ago, I asked one tech issue about LMX2594 chip RF output power.

Today, I have another tech issue during design the circuits according to the schematic of LMX2594 EVB board.

What's the RF output impedance of LMX2594 eval board?

thanks,

Jifei

CDCLVD1216: CDCLVD1216 串接电阻问题

user1359349 — Wed, 29 Jul 2026 07:34:05 GMT

Part Number: CDCLVD1216

TI的专家你好

请问CDCLVD1216 这个芯片，
1：如果输入信号是有源（3.3V）差分晶振提供的156.25M的LVPECL时钟，下图这个电子必须串接75R的吗，串接22R可以吗，如果串接22R，会导致什么后果？
2：下图2中，圈出来的地方，设计是否正确
请帮忙看看，谢谢

CDCLVP1204: CDCLVP1204RGTR的VACREF引脚处理询问

Xu Allen — Tue, 28 Jul 2026 02:11:23 GMT

Part Number: CDCLVP1204

你好，

请问一下，CDCLVP1204RGTR输入差分时钟信号是直流耦合、VCC=3.3V情况下，VACREF引脚的处理能否悬空？若不能，请问推荐如何处理？

CDCLVC1310: cdclvc1310使用晶体时，晶体不起振

user1391108 — Tue, 28 Jul 2026 01:47:49 GMT

Part Number: CDCLVC1310

cdclvc1310的11、12脚接20M晶体使用时，晶体无法起振，是什么原因？电路图及晶体规格书见下面的图，晶体的Rr小于等于50欧姆。

LMX2820: LMX2820 有时会失锁，必须要在R1跟R0之间加入延时2ms以上才可以，这是为什么？

user6341179 — Mon, 27 Jul 2026 07:47:58 GMT

Part Number: LMX2820

这是我的配置寄存器表，在最后写入R0寄存器。

LMY2820_LO1_Write_one(0x4F011e);
LMY2820_LO1_Write_one(0x4E0000|m);
LMY2820_LO1_Write_one(0x4D0708);
LMY2820_LO1_Write_one(0x4A0008);
LMY2820_LO1_Write_one(0x4600FE);
LMY2820_LO1_Write_one(0x440020);
LMY2820_LO1_Write_one(0x400080);
LMY2820_LO1_Write_one(0x2D46DC);
LMY2820_LO1_Write_one(0x2C0003);
LMY2820_LO1_Write_one(0x2B0000|Ml);//
LMY2820_LO1_Write_one(0x2A0000|Mh);
LMY2820_LO1_Write_one(0x2786A0);//·??=100000
LMY2820_LO1_Write_one(0x260001);
LMY2820_LO1_Write_one(0x240000|N);
LMY2820_LO1_Write_one(0x233100);
LMY2820_LO1_Write_one(0x220010);
LMY2820_LO1_Write_one(0x210000);//---------------------------------------
LMY2820_LO1_Write_one(0x201001);
LMY2820_LO1_Write_one(0x1F0401);//---------------------------------------
LMY2820_LO1_Write_one(0x1EB18C);//---------------------------------------
LMY2820_LO1_Write_one(0x1D318C);//---------------------------------------
LMY2820_LO1_Write_one(0x1C0639);//---------------------------------------
LMY2820_LO1_Write_one(0x1B8001);//---------------------------------------
LMY2820_LO1_Write_one(0x1A0DB0);//---------------------------------------
LMY2820_LO1_Write_one(0x190624); //---------------------------------------
LMY2820_LO1_Write_one(0x180E34);//---------------------------------------
LMY2820_LO1_Write_one(0x171102);//---------------------------------------
LMY2820_LO1_Write_one(0x16E2BF);
LMY2820_LO1_Write_one(0x151C64);//---------------------------------------
LMY2820_LO1_Write_one(0x14272C);//---------------------------------------
LMY2820_LO1_Write_one(0x132120);//---------------------------------------
LMY2820_LO1_Write_one(0x120000);//---------------------------------------
LMY2820_LO1_Write_one(0x1115C0);
LMY2820_LO1_Write_one(0x101708);
LMY2820_LO1_Write_one(0x0F2001);
LMY2820_LO1_Write_one(0x0E3001);//2?????
LMY2820_LO1_Write_one(0x0D0038);
LMY2820_LO1_Write_one(0x0C0408);
LMY2820_LO1_Write_one(0x0B0602);
LMY2820_LO1_Write_one(0x0A0000);
LMY2820_LO1_Write_one(0x090005);//---------------------------------------
LMY2820_LO1_Write_one(0x08C802);//---------------------------------------
LMY2820_LO1_Write_one(0x070000);//---------------------------------------
LMY2820_LO1_Write_one(0x060A43);//---------------------------------------
LMY2820_LO1_Write_one(0x050032);//---------------------------------------
LMY2820_LO1_Write_one(0x044204);//---------------------------------------
LMY2820_LO1_Write_one(0x030041);//---------------------------------------
LMY2820_LO1_Write_one(0x0281F4);
LMY2820_LO1_Write_one(0x0157A0);
delay_ms(2);
LMY2820_LO1_Write_one(0x006074);
delay_us(200);

LMK3H2104: LMK3H2104 Pin Configuration

kimi liang — Fri, 24 Jul 2026 06:38:36 GMT

Part Number: LMK3H2104

Hi All,

We are looking for alternative components for the following design and we found TI's LMK3H2104A06LRGER. According to the datasheet, PIN6 and PIN8(we don't use) of the TI part should be left floating if not used, but our design uses pull-up and pull-down. Is this acceptable? And also help me check if replacing the following design with TI would be okay?Thanks so much.

LMK04832: LMK04832 SPI 无响应，而LMK04828可以是为啥

HJK — Wed, 15 Jul 2026 10:44:59 GMT

Part Number: LMK04832
Other Parts Discussed in Thread: LMK04828,

同样的硬件设计，同样的板子，LMK04832 SPI 无响应，而LMK04828可以是为啥

LMK04832 SPI 无响应，而LMK04828可以
单独看LMK04832电流很低3.3V/0.057A，而LMK04828 电流3.3V/0.38A

LMX2594: what's the power output for 915MHz?

Jifei Chen — Tue, 14 Jul 2026 01:45:11 GMT

Part Number: LMX2594

Hello!

Via register configration, LMX2594 Differential RF output frequency is 915MHz, the RF output RFoutAM/RFoutAP are only pulluped 50R connected to VccRF in my HW circuits.

what's the power ouput like this HW configuration?

thanks!

Chen

LMX2594: what's the power output for 915MHz?

Jifei Chen — Tue, 14 Jul 2026 01:43:02 GMT

Part Number: LMX2594

Hello!

Via register configration, LMX2594 Differential RF output frequency is 915MHz, the RF output RFoutAM/RFoutAP are only pulluped 50R connected to VccRF in my HW circuits.

what's the power ouput like this HW configuration?

thanks!

Chen

LMK04832: LMK04832 工作不起来

HJK — Mon, 13 Jul 2026 04:40:21 GMT

Part Number: LMK04832
Other Parts Discussed in Thread: LMK04828,

LMK04832上电直接读芯片ID寄存器没反应，而换成LMK04828有反应且正确
重新更换新的LMK04832也是没反应
独看LMK04828的供电电流3.3V/0.38A，但是LMK04832的电流很低3.3V/0.057A测试过每个电源引脚电压都是有的，而且焊接没问题
为什么LMK04832和04828在同样的板上/设计上表现会有区别？

LMK04832: Multi-Device LMK04832 Synchronization

chris jxlxf — Fri, 26 Jun 2026 05:56:07 GMT

Part Number: LMK04832

When performing synchronization of multiple LMK04832 devices, I use a cascading method. After synchronizing one LMK04832 individually, I use its output as a SYNC pulse signal, which is connected to the SYNC pins of the other two LMK04832 devices. Once these two LMK04832 devices complete their individual synchronization and receive the SYNC pulse, register 0x0144 changes from 0x00 to 0xFF, and register 0x0139 changes from 0x00 to 0x03. The external reference clock is 100 MHz, and both synchronization and equal-length input adjustments have been performed. However, even after completing the above operations, each time the devices are powered on and the synchronization procedure is carried out, the rising edges of the sysref outputs from the two LMK04832 devices sometimes almost completely coincide, while other times they differ by approximately 200 ps. I have also tried adjusting the analog delay, but to no effect. How should I adjust the setup to ensure that after each power-on and completion of the synchronization procedure, the sysref phase is consistently fixed?

LMX2571: FSK_I2S does not work with LMX2571

user5114453 — Wed, 24 Jun 2026 04:32:16 GMT

Part Number: LMX2571

we set LMX2571 as FSK_I2S_FS_POL_ACTIVE_HIGH and FSK_I2S_CLK_POL_Rising_Edge_strobe, FSK_EN = TRUE.

waveform of I2S is sent as follows, WS/CLK/DAT.But no frequency deviation

LMK1C1102: 交流耦合的方式给LMK1C1102提供输入信号

zhonghang wang — Tue, 16 Jun 2026 05:38:06 GMT

Part Number: LMK1C1102

如果采用交流耦合的方式给LMK1C1102提供输入信号，需要外加偏置电压吗？偏置电压是多少呢？

LMX2592: PLLatinum Sim仿真问题

Wei Fang — Tue, 16 Jun 2026 03:35:21 GMT

Part Number: LMX2592

TI的同事

您好，最近使用贵司的PLLatinum仿真LMX2592发现一个奇怪现象，仿真得到FPD杂散分别为-97.5dBc@100MHz 但是仿真图却显示4.7dBc@100MHz.如图所示，请问一下这个是软件bug 还是我设置的不对，软件使用2025.11.17发布的1.6.9.1官方最新文档，但是我使用老版本，2025.01.10发布的1.6.8.0未出现该问题，但是该版本官方已无下载渠道

LMK1C1102: 输入一个正弦波信号是否会恶化抖动

zhonghang wang — Fri, 12 Jun 2026 03:46:59 GMT

Part Number: LMK1C1102

如果给LMK1C1102输入一个正弦波信号，幅度满足要求，但压摆率可能不满足要求，这样会恶化输出信号的抖动吗？

CDCI6214: CDCI6214: Issue with 10MHz to 100MHz frequency multiplication (Reg 0x07 always reads 0x0C10)

Eric Chen — Mon, 08 Jun 2026 06:39:19 GMT

Part Number: CDCI6214
Other Parts Discussed in Thread: TICSPRO-SW, CDCE6214

Hi everyone,

We are trying to use the CDCI6214 to multiply a 10MHz OCXO output to 100MHz for our FPGA.

Hardware Setup:

Pin 1: 10MHz square wave from the OCXO.
Pin 2: 12pF 50V capacitor to GND.
Pin 3: 3.3V supply.
Pin 4: Pulled to GND via a 4.7k resistor.
Pins 5 & 6: Left floating.
Pin 8: Connected to a reset IC.
Pins 12 & 19: Connected to the host I2C bus.

(I've attached our current schematic for reference.)

Issues Encountered: We found that the reset IC wasn't working properly, and Pin 11 doesn't support single-ended output. To work around the reset issue, we removed the reset IC and manually pulled Pin 8 low during power-up to satisfy the chip's power-up timing requirements.

After doing this, we can successfully read and write configurations via I2C from the host.

Current Goal & Configuration: We want to use the simplest possible configuration just to get the chip working and verify the signal path from input to output before moving on to further debugging. Our current register configuration is:

Addr Op Value
0x01 write 0x6A22
0x1A write 0x0B01
0x1B write 0x0001
0x1D write 0x4032
0x05 write 0x0000
0x00 write 0x0004
wait 1 second
0x07 read -> 0x0C10

We’ve tried several other configuration combinations, but whenever we read Register 0x07, the result is always 0x0C10.

Could anyone provide some advice or suggestions on how to troubleshoot and resolve this issue?

Thanks in advance!