công cụ tìm kiếm bảng dữ liệu linh kiện điện tử |
|
X1226V8 bảng dữ liệu(PDF) 9 Page - Intersil Corporation |
|
X1226V8 bảng dữ liệu(HTML) 9 Page - Intersil Corporation |
9 / 25 page 9 FN8098.3 May 8, 2006 Programmable Frequency Output Bits—FO1, FO0 These are two output control bits. They select one of three divisions of the internal oscillator, that is applied to the PHZ output pin. Table 4 shows the selection bits for this output. When using the PHZ output function, the Alarm IRQ output function is disabled. Table 4. Programmable Frequency Output Bits ON-CHIP OSCILLATOR COMPENSATION Digital Trimming Register (DTR) — DTR2, DTR1 and DTR0 (Non-Volatile) The digital trimming Bits DTR2, DTR1 and DTR0 adjust the number of counts per second and average the ppm error to achieve better accuracy. DTR2 is a sign bit. DTR2 = 0 means frequency compensation is > 0. DTR2 = 1 means frequency compensation is < 0. DTR1 and DTR0 are scale bits. DTR1 gives 10 ppm adjustment and DTR0 gives 20 ppm adjustment. A range from -30ppm to +30ppm can be represented by using three bits above. Table 5. Digital Trimming Registers Analog Trimming Register (ATR) (Non-volatile) Six analog trimming Bits from ATR5 to ATR0 are pro- vided to adjust the on-chip loading capacitance range. The on-chip load capacitance ranges from 3.25pF to 18.75pF. Each bit has a different weight for capaci- tance adjustment. Using a Citizen CFS-206 crystal with different ATR bit combinations provides an esti- mated ppm range from +116ppm to -37ppm to the nominal frequency compensation. The combination of digital and analog trimming can give up to +146ppm adjustment. The on-chip capacitance can be calculated as follows: CATR = [(ATR value, decimal) x 0.25pF] + 11.0pF Note that the ATR values are in two’s complement, with ATR(000000) = 11.0pF, so the entire range runs from 3.25pF to 18.75pF in 0.25pF steps. The values calculated above are typical, and total load capacitance seen by the crystal will include approxi- mately 2pF of package and board capacitance in addi- tion to the ATR value. See Application Section and Intersil’s Application Note AN154 for more information. WRITING TO THE CLOCK/CONTROL REGISTERS Changing any of the nonvolatile bits of the clock/control register requires the following steps: – Write a 02h to the Status Register to set the Write Enable Latch (WEL). This is a volatile operation, so there is no delay after the write. (Operation pre- ceeded by a start and ended with a stop). – Write a 06h to the Status Register to set both the Register Write Enable Latch (RWEL) and the WEL bit. This is also a volatile cycle. The zeros in the data byte are required. (Operation preceeded by a start and ended with a stop). – Write one to 8 bytes to the Clock/Control Registers with the desired clock, alarm, or control data. This sequence starts with a start bit, requires a slave byte of “11011110” and an address within the CCR and is terminated by a stop bit. A write to the CCR changes EEPROM values so these initiate a nonvolatile write cycle and will take up to 10ms to complete. Writes to undefined areas have no effect. The RWEL bit is reset by the completion of a nonvolatile write cycle, so the sequence must be repeated to again initiate another change to the CCR contents. If the sequence is not completed for any reason (by send- ing an incorrect number of bits or sending a start instead of a stop, for example) the RWEL bit is not reset and the device remains in an active mode. – Writing all zeros to the status register resets both the WEL and RWEL bits. – A read operation occurring between any of the previ- ous operations will not interrupt the register write operation. FO1 FO0 Output Frequency (average of 100 samples) 00 Alarm IRQ output 0 1 32.768kHz 1 0 4096Hz 11 1Hz DTR Register Estimated frequency PPM DTR2 DTR1 DTR0 00 0 0 01 0 +10 00 1 +20 01 1 +30 10 0 0 11 0 -10 10 1 -20 11 1 -30 X1226 |
Số phần tương tự - X1226V8 |
|
Mô tả tương tự - X1226V8 |
|
|
Link URL |
Chính sách bảo mật |
ALLDATASHEET.VN |
Cho đến nay ALLDATASHEET có giúp ích cho doanh nghiệp của bạn hay không? [ DONATE ] |
Alldatasheet là | Quảng cáo | Liên lạc với chúng tôi | Chính sách bảo mật | Trao đổi link | Tìm kiếm theo nhà sản xuất 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 |