DC2254A-A Analog Devices

DEMO MANUAL DC2254A LTC2956 Wake-Up Timer with Pushbutton Control Description Demonstration circuits 2254A-A and 2254A-B feature the The DC2254A allows easy access to all the pins necessary LTC2956-1 and LTC2956-2, respectively. The LTC 2956 to configure the device. Onboard jumpers, and an 8-pin is a micropower, wide input voltage range, configurable DIP switch provide a range of value options, to set the wake-up timer with pushbutton control. It periodically wake-up timer, wake-up timer period and long power down wakes up and turns on a connected system to perform time. Turrets are also present, allowing direct access to all tasks like monitoring temperature or capturing images. the pins present on the LTC2956 to allow easy interfacing After completing the task, the LTC2956 turns the system with a system with arbitrary requirements. off to conserve power. The wake-up timer period can be Design files for this circuit board are available at adjusted from 250ms to 39 days. DEMO MANUAL DC2254A Dc 2254a t U D JUM De F JUMPER AND SWITCH SETTINGS PB: This turret is already driven by the pushbutton present on the demoboard, however if needed it can be driven by RANGE TIME PERIOD (JP2): Sets the time period between an external signal to simulate a pushbutton press. enable signal assertions. The two available options pres- ent on the board are 250ms and 1s. See Applications LDO IN: Can be used to provide the LT3060 with power Information in the LTC2956 data sheet and replace R11 when the LDO IN jumper is set to EXT. and/or R12 if another time is desired. LDO OUT: Output from the LT3060. The state of this tur- AWAKE TIMER (JP1): Sets the time the enable signal stays ret can be monitored by the LED labelled LED SUPPLY. asserted. The onboard capacitor can be used for an awake time of 19.9ms or an external arbitrary capacitor can be DIGITAL CONNECTIONS used to set a user defined enable time. The maximum EN/EN: Active high (LTC2956-1) or active low (LTC2956-2) allowed awake time is set at 13.3ms/nF. signal. Should go active either with a debounced pushbut- LDO IN (JP3): Choose the input to the onboard LT3060 ton press or after a valid time period set by the RANGE regulator. It can either be set to INT to have it connected TIME PERIOD jumper. to the VIN pin, or EXT in order to have it driven by the ONALERT: This turret pulls low whenever the part goes LDO IN turret. See the Operating Principles section. Only from SHUTDOWN mode to RUN mode. The signal stays for LED/Monitor circuitry. low while the EN/EN pin is asserted and it can be used as SW1: This 8 pin DIP switch can be used to initialize the an input to a system to request for initial boot up routine. part in either RUN or SHUTDOWN mode and also allows This turret may be left open if unused. configuration of the t time. See Applications Infor- LONG OFFALERT: This turret pulls low for 1 second whenever mation in the LTC2956 data sheet for more information. the part goes from RUN mode to SHUTDOWN mode. SW2: This pushbutton switch controls the input to the PB This pin can be connected to the interrupt input (with a pin. This is an active low input with a 900k pull up to an pullup resistor to the system supply) of a system to alert internal 3.3V regulated supply. When the pushbutton is the system before shutdown. This pin may be left open pressed, EN/EN pin gets asserted after an initial debounce if unused. time of 32ms. SLEEP: This turret is an input and is active during RUN mode. In the Awake state, a falling edge at the SLEEP input EXTERNAL CONNECTIONS will de-assert EN/EN and put the system into the Sleep state. Signal connections are made via the row of turret posts If the SLEEP input goes high during the Sleep state, the along the edges of the board. LTC2956 reenters the Awake state and re-asserts EN/EN to turn a system on. Holding this turret high for more GND: (3 Turrets) These turrets are connected directly to than t (which is set by SW1) will force the LTC2956 LONG the ground planes. into SHUTDOWN mode. See data sheet for more details. VIN: Connect a 1.6V to 36V power supply to this turret. PBOUT: This turret follows the debounced PB input. This ONMAX: Connect a capacitor from this turret to GND if turret may be left open if unused. an arbitrary awake time is desired. Use the relationship t = 13.3ms/nF. Set the AWAKE TIMER jumper AWAKETIME to EXTERNAL if using this turret. dc2254af 2 initions per an rret