 |
数据搜索系统，热门电子元器件搜索 |
|
|
数据搜索系统，热门电子元器件搜索 |
|
L9908 数据表(PDF) 45 Page - STMicroelectronics |
|
|
|||||||||||||||||||||||||||||
L9908 数据表(HTML) 45 Page - STMicroelectronics |
|
|
45 / 152 page  5.9.1 Spread Spectrum Modulation (SSM) L9908 clocks generator implements a frequency modulation (Spread Spectrum Modulation) feature to reduce the main logic and Charge Pumps emissions around the main frequency by spreading the power spectrum over a larger frequency range. Table 36. Clock spread spectrum electrical characteristics Symbol Parameter Min Typ Max Unit Notes SSM_spreading Spread Spectrum Modulation spreading range 1 3 5 % Not subject to production test SSM_freq Spread Spectrum Modulating frequency - 156.25 kHz Not subject to production test Note: All parameters are guaranteed and tested, in the voltage ranges reported above in Table 5 unless otherwise specified. Where not specified the parametrical operating range equals the functional operating range. The clock spread spectrum modulation function can be enabled by the dedicated SPI bit CLK_SSM_EN in the register GEN_CFG1 as follows: Table 37. Clock spread spectrum enable bit CLK_SSM_EN Description 0 Clock SSM Disabled (Default) 1 Clock SSM Enabled Note: When the clock spread spectrum is enabled the internal digital timings are affected by a timing jitter equal to the selected spread spectrum spreading range. 5.9.2 Internal Clock Monitor (ICM) The correct operation and the precision of the internal synchronization signal are safety relevant and therefore L9908 implements a monitoring unit to detect abnormal deviation of the clock signal frequency. The monitoring unit is based on the use of two oscillators and two monitor chains (a Main one and an Auxiliary one) to avoid common-cause failures. Each monitor chain compares the other clock period, the first one samples CLK1 by means of CLK2 and the second one samples CLK2 by means of CLK1. If TCLK1 ≥ ICM_timeout_th: the flag INT_RST and CLK1_TIME_OUT are set. If TCLK2 ≥ ICM_timeout_th: the flag CLK2_TIME_OUT is set. The error flags remain set until the failure condition is removed and the flags are cleared by the SPI command. The correct level of clock monitor is safety relevant and then a self-check procedure is implemented on its monitor. Table 38. Internal clock monitor electrical characteristics Symbol Parameter Min Typ Max Unit Notes ICM_err_th ICM frequency mismatch threshold accuracy 24 30 36 % Application information ICM_timeout_th ICM timeout accuracy 30 50 70 us Application information Note: If no oscillator clock is available, the SPI data processing cannot work properly: L9908 delivers always the latest answer. 5.10 Motor Battery Monitor (MBM) L9908 implements a monitoring unit on the voltage level of the motor`s battery through the pin VDH with the purpose of detecting over-voltage events that can harm the device and under-voltage events that can prevent a correct motor driving. Hysteresis on thresholds and filtering time are implemented. If VDH ≤ VDH_uv_th occurs for an interval longer than T_vdh_uv_flt filtering time, VDH_UV flag is set. The error flag remains set until the failure condition is removed and the flag is cleared by the SPI command. L9908 Functional description DS13546 - Rev 5 page 45/152 |
|
链接网址 |
| ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 数据表链接 | 链接交换 | 制造商名单 All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
Chinese ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
