KickStarter Chip

www.DataSheet4U.com DS1227 DS1227 KickStarter Chip FEATURES • Provides step-up regulation and microenergy management for battery-operated systems 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 • Converts +3V to +6V DC input power source to +5V DC out for system power • “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 • Provides 3 auxiliary power outputs for independent powering of system functions • 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 management 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 primary +5V output, typically tied to the microcontroller’s VCC 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 independently enabled or disabled under software control. 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, individual portions of the system can be powered only 022698 1/20 DS1227 when they are required, minimizing the energy consumption of the system. The Kickstarter activates or kickstarts the primary VCC output in response to external momentary low-going signals. Examples of such signals include a clock/calendar 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 simple pushbutton switch. In addition, the DS1227 kickstarts primary system power 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 using minimum energy, and then go back to sleep until the DS1227 is signalled to kickstart system operation once again. PIN DESCRIPTION PIN BOOST VDCO VDCI GND VCCO1 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 VCCO1. 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 VCCO1; edge-triggered active low. VCCO1 Power On signal output; Indicates when VCCO1 is powered on; Sometimes required for controlling external tri-state buffers in systems where microenergy management techniques are employed. Auxiliary switched supply voltage outputs. On/Off controls for VCCO2/VCCO3; level activated. DESCRIPTION VCCO2 ON2/OFF2 ON3/OFF3 VCCO4 ON4 SENSE MODE4 RXIN RXOUT OSCEXT Output Input Input Output Input Input Input/Output Input Output Output Momentarily switched VCC output. VCCO4 trigger; edge activated; active low. Sense input sampled just prior to VCCO4 off; turns on VCCO1 if active; active high. Selects VCCO4 on time; level sensitive input/current source output. Serial I/O input; On control for VCCO1 when serial activity detected; edge activated. Serial I/O output; Echos incoming serial data from RXIN when VCCO1 is turned on. Oscillator Signal Output; Gated by internal comparator when BOOST is enabled. Continuous when BOOST is disabled. 022698 2/20 DS1227 INPUT SUPPLY VOLTAGE The Kickstarter is capable of operating either in a regulated 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 VCCO1, VCCO2, or VCCO3 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. VDCI is used for the DC power supply input and is tied through an inductor (270 µH typical) to a +3V lithium cell. VDCO is the main DC output which is switched to the VCCO1, VCCO2, and VCCO3 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 Operation” section of this data sheet. Figure 2 and Figure 3 illustrate the required configurations to select the supply voltage Pass-Through mode of operation. In both of these configurations the BOOST pin should be strapped directly to the VDCO 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 kickstarting occurs. When a +5V supply is used as the input DC power source, it should be directly connected to the VDCO in parallel with a filter capacitor as shown in Figure 2. The VDCI input itself should be grounded in this configuration. If a +6V supply is used, then it should be connected to the VDCI pin. A filter capacitor should still be connected to VDCO. The voltage on VDCO and subsequently on VCCO1, VCCO2, and VCCO3 (when they are enabled following kickstarting) will be a diode drop below the VDCI voltage. In both the Boost and Pass-Through modes, the DS1227 uses the voltage on VDCO as its own internal supply. DS1227 BOOST MODE CONFIGURATION Figure 1 DS1227 KICKSTARTER 270 uH (typ.) VDCI + +3V – VDCO 100 uF Filter (typ.) BOOST GND VCC01 VCC02 VCC03 .01 uF Bypass (typ.) 022698 3/20 DS1227 DS1227 +5V PASS-THROUGH MODE CONFIGURATION Figure 2 DS1227 KICKSTARTER VDCI VCC01 VCC02 VCC03 BOOST VDCO + +5 – 10 uF (typ.) GND DS1227 +6V PASS-THROUGH MODE CONFIGURATION Figure 3 DS1227 KICKSTARTER VDCI + +6V – BOOST VDCO 10 uF (typ.) GND VCC01 VCC02 VCC03 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 activity from an external stimulus applied to one of three input pins and kickstart system power by applying voltage from the input power source to the primary VCCO output (VCCO1). 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 converter is started and the voltage on VDCO will be boosted from its initial VBAT level to VDCON before VCCO1 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 VDCO line will be switched to the VCCO1 pin immediately following the detection of an active transition on a stimulus input. 022698 4/20 DS1227 Initially, when VCCO1 is off, the INT/ACK pin is collapsed to ground. At the time that voltage is switched to the VCCO1 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 occurred. 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 performs 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 acknowledged and the DS1227 is in a power on condition, the INT/ACK pin will be again taken low to signal the detection of active signalling on the ON1 or SENSE inputs. Further activity on the RXIN input will not cause a subsequent interrupt condition. The INT/ACK can be returned 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 VCCO1 output under software control. It is typically interfaced to the system microcontroller via a port pin configured as an output. As noted above, it is active only when VCCO1 is on and INT/ACK has been set high. circuit is then momentarily powered from the Kickstarter’s VCCO4 output in response to a negative going edge applied to the ON4 input. VCCO4 will stay powered for an amount of time determined by the circuitry on the MODE4 pin. During the time that VCCO4 is on, the SENSE pin has an internal pulldown device which is activated. SENSE is sampled just prior to the VCCO4 output being disconnected. I