DS1227 Datasheet, PDF (14/20 Pages) Dallas Semiconductor – KickStarter Chip

DS1227
VOLTAGE INVERTOR AND DOUBLER CONFIGURATIONS Figure 9
DS1227
KICKSTARTER
OSCEXT
1N418
+
+
10 µF 10 µF
1N4148
V_OSCEXT = -(V_DCO - 2V_F)
DS1227
KICKSTARTER
V_DCO
1N4148 1N4148
+
OSCEXT
V_OSCEXT = 2(V_DCO - V_F)
NOTE: V_F = FORWARD 1N418 DIODE VOLTAGE
APPLICATION BRIEF
The schematic shown in Figure 10 illustrates a typical
application of the DS1227 Kickstarter in a microcontrol-
ler-based, battery powered system. Together with the
Kickstarter, the system incorporates a DS5000FP Soft
Microcontroller, a DS1283 Watchdog Timekeeper, and
a DS1275 Line Powered RS232 Transceiver. Although
the system is not designed to serve a specific applica-
tion, this chip set could serve the majority of require-
ments for many types of hand-held instruments.
Using the illustrated configuration provides the following
major features:
• Permanently powered operation from a +3V
source for many applications
• Data and event logging with time stamp and
date
• Reprogrammable through RS232
serial interface
• Buttonless (autonomous) operation for many
tasks
COMPONENT DESCRIPTION
The DS5000FP is an 8-bit microcontroller which is
instruction set-compatible with the industry standard
8051. It provides an embedded interface to 32 Kbytes of
nonvolatile static RAM which can be dynamically parti-
tioned for program and data storage, and may be loaded
at any time via the on-chip serial port. With proper selec-
tion of RAM and the backup lithium source, nonvolatile
storage can be maintained for over 10 years in the ab-
sence of V_CC. The DS5000FP offers the standard low
power operating and standby modes (i.e., Idle, Stop).
More importantly, sophisticated crashproof circuitry in
conjunction with the lithium energy source allows it to re-
tain its entire operating state for the duration of a power
outage without drawing current from its V_CC line.
Timekeeping is provided by the DS1283 Watchdog
Timekeeper. Incorporating a self-contained clock and
calendar, the DS1283 tracks hundredths of seconds,
seconds, minutes, hours, days, date of the month,
month, and years. When its chip enable is inactive (no
read or write), the DS1283 consumes extremely low
current, typically 500 nA. Two alarm functions are pro-
vided: a time-of-day Alarm, and a watchdog alarm. The
time-of-day Alarm can generate an interrupt pulse up to
one week in advance of the current time. The watchdog
alarm can produce an interrupt at regular intervals rang-
ing from .01 seconds to 99.99 seconds. Both alarms
function when the part is operating in low power standby
mode.
022698 14/20