You want a timer IC which wakes up a device or system with wake up period range of 250 milli seconds to 39 days. Well there are plenty of 555 timer circuits and 8 bit microcontroller based RTC based chips but the problem with 555 timer is power consumption, lot of external components and also range of control. Where as the problem with microcontroller circuit is you need to write a code and also consume more power .
The new wake-up timer with pushbutton control IC LTC2956 from Linear Technology operating from 1.5V to 36V while “sleeping” consumes only 800nA of quiescent current from a battery or rail.
LTC2956 ca be used to perform routine tasks, such as monitoring human body temperature, monitoring strain in a bridge, or capturing images, benefit from adjustable timing options without the need to program devices or upgrade firmware. The LTC2956 periodically “wakes up” and turns on a system to perform these tasks, then turns the system off to conserve power. The wake-up period is resistor-adjustable from 250ms to 39 days, requires no code, and enables users to easily set device countdown timers via jumpers or switches.
LTC2956 are ideal for single-cell, multicell and high voltage devices, including intervalometers, which are used in time-lapse photography or military countermeasure applications, as well as “heartbeat” timers. A ±25kV ESD protected pushbutton input starts the wake-up timer, allowing users to issue a short pushbutton press to override the timer for early wake-up or to issue a long pushbutton press to stop the timer completely and put the entire system to sleep with 300nA IQ. The LTC2956 can also be configured to power up with the wake-up timer running automatically without the need of a pushbutton press. An adjustable watchdog timer allows users to limit the time a system is “awake” to prevent faulty microcontrollers or software from keeping a system on indefinitely until battery power is drained.
The LTC2956 is now available in both positive (LTC2956-1) and negative (LTC2956-2) enable polarities, and in 12-lead 3mm x 3mm DFN or 12-lead MSOP packages. Offered over the commercial and industrial temperature ranges, the LTC2956 is priced starting at $1.98 each in 1000-piece quantities.
Summary of Features: LTC2956
* Wide Input Supply Range: 1.5V to 36V
* Adjustable Wake-Up Period: 250ms to 39 Days
* 800nA Quiescent Current
* Low Leakage EN Output Allows DC/DC Converter Control (LTC2956-1)
* High Voltage EN Output Drives External P-Channel MOSFET (LTC2956-2)
* Debounced Pushbutton Status Output
* Pushbutton Interrupt
* Adjustable Power-Off Timer
* ±25kV ESD HBM on /PB Input
* 12-Lead 3mm x 3mm QFN & MSOP Packages