DS1227
DS1227
KickStarter Chip
FEATURES
•
Provides
PIN ASSIGNMENT
VCCO2
VCCO3
VCCO1
PWRON
VDCO
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VCCO4
MODE4
SENSE
INT/ACK
OSCEXT
BOOST
ON1
ON4
RXIN
RXOUT
step-up regulation and microenergy
management for battery-operated systems
DC out for system power
•
Converts +3V to +6V DC input power source to +5V
•
“Kickstarts” system power upon detection of external
stimuli:
-
-
-
-
Clock/calendar alarm
Sensor trip; such as from a photo diode
Incoming activity to a serial port
Any low-level signal transition
VDCI
GND
ON/OFF3
OFF1
ON2/OFF2
•
Shuts
down microcontroller power under software
control when operation complete
powering of system functions
•
Provides 3 auxiliary power outputs for independent
•
Allows design of “power on demand” systems
•
Insures maximum life of main power source
•
Ideally suited for DS5000-based systems
•
Available in 20-pin DIP or SOIC packages
•
Operating temperature range of –40°C to +85°C
20-Pin DIP (300 Mil)
See Mech. Drawing - Sect. 16, Pg. 1
VCCO2
VCCO3
VCCO1
PWRON
VDCO
VDCI
GND
ON/OFF3
OFF1
ON2/OFF2
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VCCO4
MODE4
SENSE
INT/ACK
OSCEXT
BOOST
ON1
ON4
RXIN
RXOUT
20-Pin SOIC (300 Mil)
See Mech. Drawing - Sect. 16, Pg. 6
ORDERING INFORMATION
DS1227:
DS1227S:
20-Pin DIP
20-Pin SOIC
DESCRIPTION
The DS1227 Kickstarter is a unique CMOS circuit which
combines power conversion and microenergy manage-
ment functions for battery operated systems. Using its
integral DC-DC converter, the DS1227 supplies +5V on
demand from either a 3– or 6–volt battery input. The pri-
mary +5V output, typically tied to the microcontroller’s
V
CC
pin, is “kickstarted” on in response to any one of
several possible momentary, external signal transitions.
Two auxiliary +5V power supply outputs can then be in-
dependently enabled or disabled under software con-
trol. When the primary power supply output is disabled,
also under software control, the auxiliary power supply
outputs remain in the state selected. In this manner, in-
dividual portions of the system can be powered only
022698 1/20
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
BOOST
V
DCO
V
DCI
GND
V
CCO1
ON1
INT/ACK
OFF1
PWRON1
I/O
Input
Output
Input
-
Output
Input
Input/Output
Input
Output
Regulation mode control.
Main DC supply voltage output.
Main DC supply voltage input.
System ground.
Primary switched supply voltage output.
On control for V
CCO1
. ON1 is negative edge triggered and internally pulled high
via a weak resistor.
Interrupt output/input; internally pulled low via a weak resistor during output;
level activated via strong high voltage for input.
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.
Auxiliary switched supply voltage outputs.
On/Off controls for V
CCO2
/V
CCO3
; level activated.
DESCRIPTION
V
CCO2
ON2/OFF2
ON3/OFF3
V
CCO4
ON4
SENSE
MODE4
RXIN
RXOUT
OSCEXT
Output
Input
Input
Output
Input
Input
Input/Output
Input
Output
Output
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.
Selects V
CCO4
on time; level sensitive input/current source output.
Serial I/O input; On control for V
CCO1
when serial activity detected; edge acti-
vated.
Serial I/O output; Echos incoming serial data from RXIN when V
CCO1
is turned
on.
Oscillator Signal Output; Gated by internal comparator when BOOST is en-
abled. Continuous when BOOST is disabled.
022698 2/20
DS1227
INPUT SUPPLY VOLTAGE
The Kickstarter is capable of operating either in a regu-
lated step-up DC-to-DC conversion (boost) mode or in a
non-regulated supply voltage Pass-Through mode.
In boost mode, the Kickstarter is designed to provide a
regulated +5V output on the V
CCO1
, V
CCO2
, or V
CCO3
voltage supply output pins from a +3V lithium source.
Figure 1 illustrates the standard configuration for use of
this mode. The BOOST pin should be tied low in order to
enable step-up DC-to-DC conversion. V
DCI
is used for
the DC power supply input and is tied through an induc-
tor (270
µH
typical) to a +3V lithium cell. V
DCO
is the
main DC output which is switched to the V
CCO1
, V
CCO2
,
and V
CCO3
outputs. This pin requires a large capacitor
(typically 100
µF)
to ground for the boost regulation low
pass output network. Further details of the boost voltage
regulator operation are given in the “Boost Mode Opera-
tion” section of this data sheet.
Figure 2 and Figure 3 illustrate the required configura-
tions to select the supply voltage Pass-Through mode of
operation. In both of these configurations the BOOST
pin should be strapped directly to the V
DCO
pin. This
connection causes the BOOST pin to remain at a high
level at all times that a battery is connected. As a result,
the internal boost regulator will be disabled when kick-
starting occurs. When a +5V supply is used as the input
DC power source, it should be directly connected to the
V
DCO
in parallel with a filter capacitor as shown in Figure
2. The V
DCI
input itself should be grounded in this con-
figuration.
If a +6V supply is used, then it should be connected to
the V
DCI
pin. A filter capacitor should still be connected
to V
DCO
. The voltage on V
DCO
and subsequently on
V
CCO1
, V
CCO2
, and V
CCO3
(when they are enabled fol-
lowing kickstarting) will be a diode drop below the V
DCI
voltage.
In both the Boost and Pass-Through modes, the
DS1227 uses the voltage on V
DCO
as its own internal
supply.
DS1227 BOOST MODE CONFIGURATION
Figure 1
DS1227
KICKSTARTER
270 uH (typ.)
V
DCI
+
+3V
–
V
DCO
100 uF
Filter
(typ.)
BOOST
GND
V
CC01
V
CC02
V
CC03
.01 uF
Bypass
(typ.)
022698 3/20
DS1227
DS1227 +5V PASS-THROUGH MODE CONFIGURATION
Figure 2
DS1227
KICKSTARTER
V
DCI
V
CC01
V
CC02
V
CC03
BOOST
V
DCO
+
+5
–
10 uF
(typ.)
GND
DS1227 +6V PASS-THROUGH MODE CONFIGURATION
Figure 3
DS1227
KICKSTARTER
V
DCI
+
+6V
–
BOOST
V
DCO
10 uF
(typ.)
GND
V
CC01
V
CC02
V
CC03
KICKSTARTER OPERATION
A conceptual block diagram of the internal circuitry of
the DS1227 is illustrated in Figure 4 for reference. While
in an initial power down state, the DS1227 will sense ac-
tivity from an external stimulus applied to one of three
input pins and kickstart system power by applying volt-
age from the input power source to the primary V
CCO
output (V
CCO1
). Activity detected on any of the ON1,
RXIN, and SENSE pins initiates the kickstarting action.
When kickstarting occurs and the DS1227 is configured
for boost operation, the on-chip, step-up DC-to-DC con-
verter is started and the voltage on V
DCO
will be boosted
from its initial V
BAT
level to V
DCON
before V
CCO1
is
turned on. If the DS1227 is configured for voltage
Pass-Through operation, then the DC-to-DC converter
will remain disabled and voltage on the V
DCO
line will be
switched to the V
CCO1
pin immediately following the de-
tection of an active transition on a stimulus input.
022698 4/20
DS1227
Initially, when V
CCO1
is off, the INT/ACK pin is collapsed
to ground. At the time that voltage is switched to the
V
CCO1
output pin during kickstarting, the INT/ACK pin
will be latched such that it will remain in a low state. This
signals the microcontroller that a power on reset has oc-
curred. The OFF1, ON2/OFF2, and ON3/OFF3 inputs
are all ignored until the microcontroller acknowledges
this power on reset condition. This acknowledgement is
performed via the same INT/ACK pin, which also per-
forms the function of an interrupt acknowledge input.
This is made possible due to the fact that the pin has a
weak NMOS pulldown which forms a latch. When INT/
ACK is externally driven with a sufficiently strong high
signal (as described in the “Electrical Characteristics”
section) the state of the latch will be switched and as a
result the interrupt condition will be reset.
After the power on reset interrupt has been acknowl-
edged and the DS1227 is in a power on condition, the
INT/ACK pin will be again taken low to signal the detec-
tion of active signalling on the ON1 or SENSE inputs.
Further activity on the RXIN input will not cause a sub-
sequent interrupt condition. The INT/ACK can be re-
turned to its high (reset) state again by externally driving
it with a sufficiently strong high signal.
The OFF1 input is used to turn off the V
CCO1
output un-
der software control. It is typically interfaced to the sys-
tem microcontroller via a port pin configured as an out-
put. As noted above, it is active only when V
CCO1
is on
and INT/ACK has been set high.
circuit is then momentarily powered from the Kickstart-
er’s V
CCO4
output in response to a negative going edge
applied to the ON4 input. V
CCO4
will stay powered for an
amount of time determined by the circuitry on the
MODE4 pin. During the time that V
CCO4
is on, the
SENSE pin has an internal pulldown device which is ac-
tivated. SENSE is sampled just prior to the V
CCO4
out-
put being disconnected. If SENSE is externally driven
high (V
IH
) at this time, it kickstarts V
CCO1
power. Any
time that V
CCO4
power is off, the SENSE pin appears as
a high impedance to external circuitry.
The amount of time that V
CCO4
is on is determined by
the configuration of the MODE4 pin. MODE4 is intended
to either be tied high (typically to V
DCO
) or tied to an ex-
ternal capacitor. The V
CCO4
on time is thereby deter-
mined either by the amount of time between falling
edges on ON4 or by the value of the capacitor.
If the MODE4 pin is tied high at the time that ON4 is acti-
vated, then V
CCO4
will remain on until the next falling
edge is detected on ON4. Figure 5 illustrates the timing
associated with this mode of operation. If the Kickstarter
is also configured for boost regulation and V
CCO1
,
V
CCO2
, and V
CCO3
are turned off, the DC-DC converter
will be briefly enabled so that +5V will be supplied on
V
CCO4
for the duration of the time that it is on.
The alternative MODE4 configuration is illustrated in
Figure 6A. As shown in the figure, it is recommended for
most applications that a large resistor also be con-
nected between MODE4 and ground in addition to the
capacitor. For the configuration shown, the MODE4 pin
will be sensed low by the Kickstarter just following the
negative-going edge at ON4. Following this condition, a
constant current specified as I
M4ON
is supplied out of
the MODE4 pin. This will cause the voltage on MODE4
to rise linearly. V
CCO4
will remain on until the voltage on
MODE4 reaches a threshold specified as VM4OFF (ap-
proximately 0.5 V
DCO
). At this time, V
CCO4
will be shut
off. At the same time, the constant current source on the
MODE4 pin will be disconnected and an internal resis-
tive element (specified as R
M4DIS
) will be connected be-
tween the MODE4 pin and ground. This internal resis-
tive element along with any external resistance will
cause the voltage on the capacitor to decay exponen-
tially until it reaches a threshold specified as V
M4DIS
(ap-
proximately 0.1 V
DCO
). When this condition is reached,
the internal resistive element will be disconnected, and
the MODE4 pin will appear as a high impedance until the
next active transition occurs on ON4. The external re-
STIMULUS INPUTS
ON1 is a simple TTL-level compatible input which is de-
signed to detect a negative-going edge. V
CCO1
is kick-
started whenever an active edge is detected on this pin.
The RXIN input can be used to initiate the kickstarting
action in response to the detection of incoming serial
data. In this configuration, the RXIN pin is interfaced to
an incoming serial data line, typically from an RS232
transceiver. RXOUT is the corresponding output and is
used to route the serial data to the microcontroller. RXIN
remains internally disconnected from RXOUT until
V
CCO1
is powered on. At that time, the two lines are con-
nected and serial data is passed straight through the de-
vice to the microcontroller.
The SENSE pin is intended to be connected to an exter-
nal sensor circuit which is powered from V
CCO4
. This
022698 5/20
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