QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 740 TRACKER/SEQUENCER DEMO BOARD LTC2922 DESCRIPTION Demonstration circuit 740 is a tracker/sequencer track up together a selectable time after supplies 0, demo board featuring the LTC2922 that monitors up 1, and 2 track up together. The board includes a to five external power supplies and ramps up their power-on LED that, when lit, indicates that the pri- load voltages by controlling external N-channel MOS- mary supplys load is energized. Oversized solder FETs. Automatic remote sense switching allows sup- pads under the load resistors and the circuit breaker ply generators with sense inputs to compensate for current sense resistor accommodate a wide range of voltage drops across the controlling FETs. Excessive component footprints. Solder pads on the back of current on the primary supply (Supply 0) trips an the board accommodate extra load capacitors or re- electronic circuit breaker that will disconnect all of the sistors. In addition to providing near-by ground con- loads. Four jumpers (block JP1) are provided to se- nections for each supply input and output, the board lect which non-primary supplies are monitored. The has metal ground strips that are convenient clip resistors that set the supply monitoring levels may be points for meter leads. replaced to customize the board for other supply Design files for this circuit board are available. Call voltage combinations (see the LTC2922 Datasheet). the LTC factory. Five other jumpers (blocks JP2, JP3, and JP4) allow LTC is a registered trademark of Linear Technology Corporation the board to demonstrate supply sequencing. With the proper jumper settings, supplies 3 and 4 will Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION MIN TYP MAX UNITS V (Supply 0) Voltage Typical Board DC740A-A 4.50 5.00 5.50 V CC Operating Range Board DC740A-B 2.97 3.30 3.63 V Board DC740A-C 2.37 2.50 2.63 V Load ramp rate Tracking 0.10 V/ms Sequencing, first set of loads 0.10 V/ms Sequencing, delayed set of loads 0.12 V/ms Monitor-to-Tracking Delay All monitors in compliance to start of GATE ramp 20 ms Sequencing Delay Final GATE voltage to start of PG ramp 20 ms Circuit Breaker Trip Current 3.7 4.2 4.7 A OPERATING PRINCIPLES This board may be configured to demonstrate supply In sequencing mode, the ramping of one set of sup- tracking or supply sequencing. In tracking mode, all plies follows the ramping of another set of supplies. supplies are ramped up simultaneously a selectable This demonstration board limits the possible delayed delay after all monitoring requirements are met. Sup- supplies to 3 and/or 4. The delayed supplies may ply 0, the V supply, is always monitored monitor- not take advantage or automatic remote sense CC ing of other supplies is selectable by means of jumper switching. block JP1. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 740 TRACKER/SEQUENCER DEMO BOARD Table 2. Supply Requirements for Demo Board 740A with Factory Jumper Settings SUPPLY NUMBER SUPPLY SUPPLY DEMO BOARD LOAD CURRENT ADDITIONAL VOLTAGE VARIATION VERSION COMPLIANCE LOAD CURRENT 5.0V 10% max. 740A-A >95mA 0 3.7A min. (Primary Supply = 3.3V 10% max. 740A-B >75mA 4.2A typ. V Voltage) 4.7A max. CC 2.5V 5% max. 740A-C >65mA 1 2.5V 7.5% max. 740A-A, -B, -C >30mA 4.0A max. 2 1.8V 7.5% max. 740A-A, -B, -C >25mA 4.0A max. 3 1.5V 7.5% max. 740A-A, -B, -C >20mA 3.5A max. 4 1.2V 5% max. 740A-A, -B, -C >15mA 3.5A max. QUICK START PROCEDURE Demonstration circuit 740 is easy to set up to evalu- TRACKING ate the operation of the LTC2922. Refer to Figure 1 1. Set the jumpers of block JP1 to choose which sup- for proper measurement equipment setup. To test plies, in addition to the primary supply, will be tracking operation, follow steps 1 through 3 below, monitored. For example, to monitor all supplies then proceed to step 7. To test sequencing operation, set: follow steps 4 through 6, then proceed to step 7. JP1 Supply 1 Monitor Use of remote sense switching is optional on a per supply basis (see Figure 1). It is available for all sup- JP1 Supply 2 Monitor plies in tracking applications, but only for supplies 0 JP1 Supply 3 Monitor through 2 in sequencing applications. JP1 Supply 4 Monitor The demo board is shipped with the jumpers set for 2. Set jumper JP2 to select the resistive pull-up on monitoring all five supplies and tracking of all the the PG pin: loads. In addition, a resistor pull-up to V from the CC PG pin makes the power good output a proper logic JP2 PG Function Pull-up signal. 3. Set the upper and lower jumpers of blocks JP3 and The voltage and current requirements for supply gen- JP4 to select tracking and automatic remote sense erators when the board has factory jumper settings, switching: and the factory installed values for monitoring resis- JP3 Load 3 Track tors RA1-RA4 and RB1-RB4 are summarized in JP3 Load 3 Remote Sense Table 2. Consult the LTC2922 Datasheet to calculate new resistor values to monitor supplies with different JP4 Load 4 Track voltages or tolerances. JP4 Load 4 Remote Sense External loads may be added at the load terminals. NOTE: Remote sense switching will have no effect if Make the wires as short as possible to reduce induc- supply generators sense inputs are not connected tance and resistance, and use a gauge proper for the to the boards FB turret posts. expected load currents. Proceed to step 7. 2