DS1227 Datasheet, PDF (2/20 Pages) Dallas Semiconductor – KickStarter Chip

DS1227
when they are required, minimizing the energy con-
sumption of the system.
The Kickstarter activates or kickstarts the primary V_CC
output in response to external momentary low-going
signals. Examples of such signals include a clock/ca-
lendar alarm from a DS1283 Watchdog Timekeeper, or
an incoming asynchronous serial data word from a host
PC via the DS1275 Line Powered Transceiver, or a sim-
ple pushbutton switch.
In addition, the DS1227 kickstarts primary system pow-
er in response to activity detected by an external sensor
circuit. In this case, the Kickstarter can be signalled at
regular intervals, typically from a DS1283 Watchdog
Timekeeper, to momentarily apply power to the sensor
and monitor an input for an active response.
An application using the Kickstarter has the capability to
wake-up from a ultra-low power state, perform a task us-
ing minimum energy, and then go back to sleep until the
DS1227 is signalled to kickstart system operation once
again.
PIN DESCRIPTION
PIN
I/O
DESCRIPTION
BOOST
Input
Regulation mode control.
V_DCO
V_DCI
GND
Output
Input
-
Main DC supply voltage output.
Main DC supply voltage input.
System ground.
V_CCO1
ON1
Output
Input
Primary switched supply voltage output.
On control for V_CCO1. ON1 is negative edge triggered and internally pulled high
via a weak resistor.
INT/ACK
Input/Output Interrupt output/input; internally pulled low via a weak resistor during output;
level activated via strong high voltage for input.
OFF1
PWRON1
Input
Output
Off control for V_CCO1; edge-triggered active low.
V_CCO1 Power On signal output; Indicates when V_CCO1 is powered on; Some-
times required for controlling external tri-state buffers in systems where micro-
energy management techniques are employed.
V_CCO2
ON2/OFF2
ON3/OFF3
Output
Input
Input
Auxiliary switched supply voltage outputs.
On/Off controls for V_CCO2/V_CCO3; level activated.
V_CCO4
ON4
SENSE
Output
Input
Input
Momentarily switched VCC output.
V_CCO4 trigger; edge activated; active low.
Sense input sampled just prior to V_CCO4 off; turns on V_CCO1 if active; active
high.
MODE4
RXIN
Input/Output Selects V_CCO4 on time; level sensitive input/current source output.
Input
Serial I/O input; On control for V_CCO1 when serial activity detected; edge acti-
vated.
RXOUT
Output
Serial I/O output; Echos incoming serial data from RXIN when V_CCO1 is turned
on.
OSCEXT
Output
Oscillator Signal Output; Gated by internal comparator when BOOST is en-
abled. Continuous when BOOST is disabled.
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