 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
ST72321BXXX-AUTO Datasheet(PDF) 45 Page - STMicroelectronics |
|
|
|||||||||||||||||||||||||||||
ST72321BXXX-AUTO Datasheet(HTML) 45 Page - STMicroelectronics |
|
|
45 / 247 page  ST72321Bxxx-Auto Supply, reset and clock management 45/247 6.3 Phase locked loop If the clock frequency input to the PLL is in the range 2 to 4 MHz, the PLL can be used to multiply the frequency by two to obtain an fOSC2 of 4 to 8 MHz. The PLL is enabled by option byte. If the PLL is disabled, then fOSC2 =fOSC/2. Caution: The PLL is not recommended for applications where timing accuracy is required (see Section 19.5.5: PLL characteristics on page 202). Figure 10. PLL block diagram 6.4 Multi-oscillator (MO) The main clock of the ST7 can be generated by three different source types coming from the multi-oscillator block: ● an external source ● 4 crystal or ceramic resonator oscillators ● an internal high frequency RC oscillator Each oscillator is optimized for a given frequency range in terms of consumption and is selectable through the option byte. The associated hardware configurations are shown in Table 9. Refer to Chapter 19: Electrical characteristics for more details. Caution: The OSC1 and/or OSC2 pins must not be left unconnected. For the purposes of Failure Mode and Effect Analysis, it should be noted that if the OSC1 and/or OSC2 pins are left unconnected, the ST7 main oscillator may start and, in this configuration, could generate an fOSC clock frequency in excess of the allowed maximum (> 16 MHz), putting the ST7 in an unsafe/undefined state. The product behavior must therefore be considered undefined when the OSC pins are left unconnected. External clock source In this external clock mode, a clock signal (square, sinus or triangle) with ~50% duty cycle has to drive the OSC1 pin while the OSC2 pin is tied to ground. Crystal/ceramic oscillators This family of oscillators has the advantage of producing a very accurate rate on the main clock of the ST7. The selection within a list of four oscillators with different frequency ranges has to be done by option byte in order to reduce consumption (refer to Section 21.1.1: Flash configuration on page 228 for more details on the frequency ranges). In this mode of the 0 1 PLL OPTION BIT PLL x 2 fOSC2 / 2 fOSC |
Similar Part No. - ST72321BXXX-AUTO |
|
Similar Description - ST72321BXXX-AUTO |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
