Electronic Components Datasheet Search |
|
DS3234 Datasheet(PDF) 10 Page - Maxim Integrated Products |
|
DS3234 Datasheet(HTML) 10 Page - Maxim Integrated Products |
10 / 20 page Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM 10 ____________________________________________________________________ two programmable time-of-day alarms and a program- mable square-wave output. The INT/SQW provides either an interrupt signal due to alarm conditions or a square- wave output. The clock/calendar provides seconds, min- utes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12- hour format with AM/PM indicator. Access to the internal registers is possible through an SPI bus interface. A temperature-compensated voltage reference and comparator circuit monitors the level of VCC to detect power failures and to automatically switch to the backup supply when necessary. When operating from the back- up supply, access is inhibited to minimize supply cur- rent. Oscillator, time and date, and TCXO operations can continue while the backup supply powers the device. The RST pin provides an external pushbutton function and acts as an indicator of a power-fail event. Operation The block diagram shows the main elements of the DS3234. The eight blocks can be grouped into four functional groups: TCXO, power control, pushbutton function, and RTC. Their operations are described sep- arately in the following sections. 32kHz TCXO The temperature sensor, oscillator, and control logic form the TCXO. The controller reads the output of the on-chip temperature sensor and uses a lookup table to determine the capacitance required, adds the aging correction in the AGE register, and then sets the capacitance selection registers. New values, including changes to the AGE reg- ister, are loaded only when a change in the temperature value occurs. The temperature is read on initial applica- tion of VCC and once every 64 seconds (default, see the description for CRATE1 and CRATE0 in the Control/Status Register section) afterwards. Power Control The power control function is provided by a tempera- ture-compensated voltage reference and a comparator circuit that monitors the VCC level. The device is fully accessible and data can be written and read when VCC is greater than VPF. However, when VCC falls below both VPF and VBAT, the internal clock registers are blocked from any access. If VPF is less than VBAT, the device power is switched from VCC to VBAT when VCC drops below VPF. If VPF is greater than VBAT, the device power is switched from VCC to VBAT when VCC drops below VBAT. After VCC returns above both VPF and VBAT, read and write access is allowed after RST goes high (Table 1). To preserve the battery, the first time VBAT is applied to the device, the oscillator does not start up until VCC crosses VPF. After the first time VCC is ramped up, the oscillator starts up and the VBAT source powers the oscillator during power-down and keeps the oscillator running. When the DS3234 switches to VBAT, the oscil- lator may be disabled by setting the EOSC bit. Pushbutton Reset Function The DS3234 provides for a pushbutton switch to be con- nected to the RST output pin. When the DS3234 is not in a reset cycle, it continuously monitors the RST signal for a low going edge. If an edge transition is detected, the DS3234 debounces the switch by pulling the RST low. After the internal timer has expired (PBDB), the DS3234 continues to monitor the RST line. If the line is still low, the DS3234 continuously monitors the line looking for a rising edge. Upon detecting release, the DS3234 forces the RST pin low and holds it low for tRST. The same pin, RST, is used to indicate a power-fail con- dition. When VCC is lower than VPF, an internal power-fail signal is generated, which forces the RST pin low. When VCC returns to a level above VPF, the RST pin is held low for tREC to allow the power supply to stabilize. If the EOSC bit is set to logic 1 (to disable the oscillator in bat- tery-backup mode), the reset signal is kept active for tREC plus the startup time of the oscillator (typ 1 second). SUPPLY CONDITION READ/WRITE ACCESS ACTIVE SUPPLY RST VCC < VPF, VCC < VBAT No VBAT Active VCC < VPF, VCC > VBAT Yes VCC Active VCC > VPF, VCC < VBAT Yes VCC Inactive VCC > VPF, VCC > VBAT Yes VCC Inactive Table 1. Power Control |
Similar Part No. - DS3234_07 |
|
Similar Description - DS3234_07 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |