时钟和计时论坛 - 最近的话题

LMK04832: PLL2锁定失效

silencer123 ye — Mon, 20 Jul 2026 10:05:16 GMT

Part Number: LMK04832

在TICS Pro里显示PLL2 Locked，但烧入板子后显示未锁定。新建文本文档.txt这是寄存器文件。
由CLKin1输入10MHZ，无其他输入，借由PLL2倍频分频后输出4路40MHZ，10路160MHZ。

LMX2820: LMX2820使用完全辅助较准模式时失锁

LU GAN — Thu, 16 Jul 2026 06:50:30 GMT

Part Number: LMX2820

我们在使用LMX2820的时候，首先配置它工作在无辅助的快速VCO校准FCAL模式，正常初始化完成后芯片输出5.65GHz信号，此时LD信号为高正常锁定。。这时候通过FPGA下发SPI控制指令，使LMX2820输出6125MHz的控制指令,此时LMX2820正常输出该频率并且LD锁定信号为高。图一是频谱仪测试结果。

此时我们想让LMX2820工作在完全辅助较准模式，即通过SPI总线回读VCO_SEL,VCO_DACISET和VCO_CAPCTRL这三个控制寄存器的值，然后将这三个控制寄存器设置为FORCE强制控制模式，并通过SPI总线将这三个回读到的值下发下去。

回读的寄存器如下：

R74: 0x8665

R75: 0xC3

下发的寄存器如下：

R0: 0x6420

R10: 0x880

R23: 0x1103

R20: 0x26C3

R22: 0x2233

此时LMX2820的LD锁定信号一直为低，即失锁状态。并且LMX输出的频率也不是正常的6125MHz。配置的R图二是频谱仪测试结果。

请问可能是什么问题导致的失锁？

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!

LMX2594: LMX2594 Gets Damaged Upon Power-Up

zhiwei liu — Thu, 04 Jun 2026 14:33:58 GMT

Part Number: LMX2594

Dear TI Support Team,

I am currently using the LMX2594 in a frequency multiplication application and have encountered a critical issue. The device gets damaged immediately upon power-up, before any register configuration is performed.

The following measurements have been taken:

VCC measurement: During power-up, the VCC voltage cannot reach the nominal 3.3V, measuring only approximately 2.6V.
Supply current: With a 5V input, the combined current drawn by the OCXO and the LMX2594 is only 700mA, which remains below the LDO’s maximum rating.
Internal LDOs: The measured voltages on various internal LDOs are incorrect compared to the expected values.

At this stage, no SPI commands have been sent to the device, and yet the LMX2594 appears to be damaged. Given these observations, I would appreciate your guidance on the following:

Could the insufficient VCC voltage during power-up be responsible for damaging the device?
Are there any known startup timing or inrush current characteristics that could explain the observed behavior?
What are the most likely design issues that could cause such a failure, particularly regarding power supply decoupling, layout, or the connection between the OCXO and the LMX2594?
Do you have any specific recommendations for debugging the internal LDOs to identify the root cause?

I have attached the relevant section of my schematic for your reference. Please let me know if additional information or measurements would be helpful for the analysis.

Thank you very much for your time and assistance.

Best regards

LMX2694-EP: 回读寄存器无法切换

Hui Cao22 — Wed, 27 May 2026 12:42:50 GMT

Part Number: LMX2694-EP

我需要回读寄存器，我是手动单个寄存器读写测试，可以确认写入是没有问题的（例如复位，都是没问题的），然后我将寄存器R0的bit2置为1'b0（即muxout改为回读,写入00_2008），随后再写入80_0000（回读寄存器0），发现muxout还是为锁定指示（常1'b1），像是没切换过去，请问一下是需要其他额外寄存器写入吗？

LMK04832EVM: 如何产生几百k到几十M的方波时钟信号

T yh — Tue, 26 May 2026 08:00:39 GMT

Part Number: LMK04832EVM
Other Parts Discussed in Thread: TICSPRO-SW

根据手册提供的说明，LMK04832EVM开发板默认加载122.88MHz时钟，但我想产生几百k到几十M的方波时钟信号。我对TICSPro工具使用不太清楚，调整一些参数后，它产生的总是带小数点的信号，例如1474.45MHz。
我想请问该如何配置，使用一个外部输入的时钟，然后分频产生多路整数的，几百k到几十MHZ的方波？
SetModes、CLKinX Control、PLL1and2、Clock Outputs等位置该如何设置
另外可否转告贵司中国的技术支持团队联系方式？

LMX2592: LMX2592环路滤波器设计和寄存器设置，100M晶振

Zhijun Zhang — Sat, 16 May 2026 08:05:20 GMT

Part Number: LMX2592

尊敬的TI团队：您好！我的器件为LMX2592，输入参考频率为100MHz，VCO频率为6GHz，输出6GHz，准备选用的是二阶无源滤波器，能为我推荐一组合适的寄存器参数，和C1, C2, R2值吗？已经奋斗了三天了，一直搞不定。多谢

LMKDB1108: LMKDB1108 Vcross

zicehn liu — Thu, 14 May 2026 23:24:38 GMT

Part Number: LMKDB1108

Hello，Dear Expert,

I am a hardware engineer， we are looking for clock.buffer from different supplier，but one parameter makes me confusing， the Vcross，the definition of this spec should be the cross point of the clkp and clkn, and this device require the input vcross variation within 140mV and the output clk cross variation is also have similar requirment,but i want to know will the output vcross be affected by the input vcross? if so, will i need to make the input cross point varied by 140mV，then test the output cross variation? or i just need to make sure the input and output cross varition with the spec limitiation separately

NE555: NE555故障

guo qinqin — Tue, 12 May 2026 05:38:53 GMT

Part Number: NE555

"In our NE555 circuit configured as a 1Hz astable oscillator, which drives a 15mA LED and a buzzer, the timing components are a 100kΩ resistor and a 10µF capacitor. Normally, when powered on, the OUT pin goes high for about 2 seconds before starting oscillation. However, on some units, the OUT pin remains high for over 30 seconds before oscillation begins. This is the abnormal behavior."

LMK04832: LMK04832在Single PLL模式下，使用OSCIN参考入无输出时钟

?? ? — Mon, 11 May 2026 08:28:47 GMT

Part Number: LMK04832

你好，

我的PCB使用LMK04832，调试阶段CLKIN0/1/2均无输入时钟，OSCIN接TCXO，TCXO的频率为122.88MHz。我使用single pll模式，将PLL1 powerdown，只使用OSCIN输入的122.88M时钟配置PLL2，以生成输出所需的各个时钟。但配置完成后，示波器测试各输出管脚只有一个直流偏置电平，没有任何频率输出。

附件为配置文件，还请帮忙检查一下，为什么没有时钟输出？

谢谢

LMK04832-SINGLE-PLL-OSCIN.zip

PLLATINUMSIM-SW: 无法下载

hu hu — Thu, 07 May 2026 02:06:29 GMT

Part Number: PLLATINUMSIM-SW

显示我的账号没有权限下载

PLLATINUMSIM-SW: 无法下载

hu hu — Thu, 07 May 2026 02:05:07 GMT

Part Number: PLLATINUMSIM-SW

显示我的账号没有权限下载

LMX2594: LMX2594在A B路切换的时候没有输出信号

zhonghang wang — Mon, 27 Apr 2026 03:37:16 GMT

Part Number: LMX2594

我的应用是LMX2594的A路输出10MHz及以上频率，B路的输出后面接一个分频器产生10MHz以下的频率，扫频的时候经常出现的一个问题是跨10MHz时A路没有输出信号，比如扫频范围是1MHz~11MHz，总共扫9个点。此时测量LD信号也是高电平，但测量射频信号却没有输出。我是用的全辅助模式。我尝试把AB两路用同一条指令进行开、关切换没有解决问题，尝试把AB两路同时保持开启也没有解决问题。请问可能是什么原因？谢谢！

LMK6BEVM-DOC-CERT: TICS pro使用过程中发现在PLL2中输入参数之后在DPLL2里面没有输出

binghui yang — Fri, 24 Apr 2026 06:15:57 GMT

Part Number: LMK6BEVM-DOC-CERT
Other Parts Discussed in Thread: LMK05028EVM

用的LMK05028EVM板

LMK03328: LMK03328输出HCSL时Rs电阻咨询

linjie feng — Wed, 22 Apr 2026 14:29:40 GMT

Part Number: LMK03328

您好！说是Rs可用于限制由于快速瞬态电流引起的过冲和振铃，那么请问放在50欧偏置电阻后面不行吗？谢谢！

LMX2572: 请求LMX2572寄存器软件配置技术支持

Ya Hao Chen — Wed, 22 Apr 2026 02:45:26 GMT

Part Number: LMX2572

您好，我采购了贵司的LMX2572芯片，我们需要一年稳定采购 TI 芯片 1 万片以上，现在量产项目遇到 LMX2572芯片寄存器配置上的问题，想使用芯片上自带的自动斜坡扫描模式和2FSK调制模式，但每次以进行配置就会影响我输出的3.4GHz的主频率，主频率不输出了，而且模式也没成功开启，寄存器会重新被修改，导致对主频率输出影响。需要技术紧急支持。同时我们后续还有多个新项目，希望对接大客户专属团队，建立长期合作。麻烦帮我转接或安排资深工程师尽快回电，谢谢！