LTC2927 Datasheet | Linear Technology

Features n n n n n n n n n LTC2927 Single Power Supply Tracking Controller DESCRIPTIO .. Flexible Power Supply Tracking Tracks Both Up and Down Power Supply Sequencing Supply Stability is Not Affected Low Pin Count Controls Single Supply without Series FETs Adjustable Ramp Rate Supply Shutdown Output Available in 8-Lead Thin SOT™ and 8-Lead (3mm × 2mm) DFN Packages The LTC®2927 provides a simple solution to power supply tracking and sequencing requirements. By selecting a few resistors, the supply can be configured to ramp-up and ramp-down with differing ramp rates, voltage offsets, or time delays relative to other supplies or a master signal. By forcing current into a feedback node of an independent supply, the LTC2927 causes the output to track a ramp signal without inserting any pass element losses. Because the current is controlled in an open-loop manner, the LTC2927 does not affect the transient response or stability of the supply. The pact solution at point of load minimizes the trace length of the DC/DC circuit sensitive FB node. Furthermore, it presents a high impedance when power-up is plete, effectively removing it from the DC/DC circuit. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Thin SOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Patents Pending. U APPLICATIO S n n n n VCORE and VI/O Supply Tracking Microprocessor, DSP and FPGA Supplies Multiple Supply Systems Point-of-Load Supplies TYPICAL APPLICATIO EARLY VIN 3.3V 138k ON 100k LTC2927 SDO RAMPBUF 16.5k TRACK 13k GND FB VCC RAMP Track-Up and Track-Down Waveforms 0.1μF 0.1μF RUN/SS VIN IN DC/DC 1V/DIV OUT 1.8V FB = 1.235V 16.5k 35.7k EARLY VIN 3.3V VCC ON LTC2927 SDO RAMPBUF 887k TRACK 412k GND 2927 TA01a 0.1μF RAMP VIN RUN/SS IN DC/DC FB FB = 0.8V 887k 10ms/DIV 2927 TA01c RAMP (3.3V) 2.5V 1.8V OUT 2.5V 1V/DIV 412k RAMP (3.3V) 2.5V 1.8V 10ms/DIV 2927...