LTC2927 Single Power Supply Tracking Controller FEATURES DESCRIPTIO n Flexible Power Supply Tracking The LTC 2927 provides a simple solution to power supply n Tracks Both Up and Down tracking and sequencing requirements. By selecting a few n Power Supply Sequencing resistors, the supply can be con gured to ramp-up and n Supply Stability is Not Affected ramp-down with differing ramp rates, voltage offsets, or n Low Pin Count time delays relative to other supplies or a master signal. n Controls Single Supply without Series FETs By forcing current into a feedback node of an independent n Adjustable Ramp Rate supply, the LTC2927 causes the output to track a ramp n Supply Shutdown Output signal without inserting any pass element losses. Because n Available in 8-Lead ThinSOT and 8-Lead the current is controlled in an open-loop manner, the (3mm 2mm) DFN Packages LTC2927 does not affect the transient response or stabil- ity of the supply. The compact solution at point of load U minimizes the trace length of the DC/DC circuit sensitive APPLICATIO S FB node. Furthermore, it presents a high impedance when n V and V Supply Tracking CORE I/O power-up is complete, effectively removing it from the n Microprocessor, DSP and FPGA Supplies DC/DC circuit. n Multiple Supply Systems , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the n Point-of-Load Supplies property of their respective owners. Patents Pending. TYPICAL APPLICATIO EARLY V Track-Up and Track-Down Waveforms IN 3.3V 0.1F 138k V CC ON RAMP 0.1F V IN RAMP 100k LTC2927 (3.3V) 2.5V SDO RUN/SS IN 1V/DIV 1.8V DC/DC RAMPBUF FB FB = 1.235V OUT 1.8V 16.5k TRACK 16.5k GND 13k 35.7k 2927 TA01b 10ms/DIV EARLY V IN 3.3V 0.1F V CC RAMP ON RAMP V IN (3.3V) LTC2927 2.5V 1V/DIV SDO RUN/SS IN 1.8V DC/DC RAMPBUF FB FB = 0.8V OUT 2.5V 887k TRACK 887k GND 412k 412k 2927 TA01c 10ms/DIV 2927 TA01a 2927fb 1 U ULTC2927 ABSOLUTE AXI U RATI GS (Note 1) Supply Voltage (V ) ................................. 0.3V to 10V Average Current CC Input Voltages TRACK .................................................................5mA ON ......................................................... 0.3V to 10V FB ........................................................................5mA TRACK .........................................0.3V to V + 0.3V RAMPBUF ............................................................5mA CC Output Voltages Operating Temperature Range FB, SDO ................................................. 0.3V to 10V LTC2927C ................................................ 0C to 70C RAMP, RAMPBUF .........................0.3V to V + 0.3V LTC2927I.............................................. 40C to 85C CC Storage Temperature Range ................... 65C to 150C Lead Temperature (Soldering, 10 sec) .................. 300C PIN CONFIGURATION TOP VIEW TOP VIEW ON 1 8 V CC V 1 8 ON CC RAMP 2 7 SDO SDO 2 7 RAMP 9 RAMPBUF 3 6 FB FB 3 6 RAMPBUF TRACK GND 4 5 GND 4 5 TRACK TS8 PACKAGE 8-LEAD PLASTIC TSOT-23 DDB PACKAGE 8-LEAD (3mm 2mm) PLASTIC DFN T = 125C, = 250C/W JMAX JA EXPOSED PAD (PIN 9) PCB GND, CONNECTION OPTIONAL T = 125C, = 76C/W JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2927CDDB PBF LTC2927CDDB TRPBF LBQH 8-Lead (3mm 2mm) Plastic DFN 0C to 70C LTC2927IDDB PBF LTC2927IDDB TRPBF LBQH 8-Lead (3mm 2mm) Plastic DFN 40C to 85C LTC2927CTS8 PBF LTC2927CTS8 TRPBF LTBQJ 8-Lead Plastic TSOT-23 0C to 70C LTC2927ITS8 PBF LTC2927ITS8 TRPBF LTBQJ 8-Lead Plastic TSOT-23 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2927CDDB LTC2927CDDB TR LBQH 8-Lead (3mm 2mm) Plastic DFN 0C to 70C LTC2927IDDB LTC2927IDDB TR LBQH 8-Lead (3mm 2mm) Plastic DFN 40C to 85C LTC2927CTS8 LTC2927CTS8 TR LTBQJ 8-Lead Plastic TSOT-23 0C to 70C LTC2927ITS8 LTC2927ITS8 TR LTBQJ 8-Lead Plastic TSOT-23 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. For more information on lead free part marking, go to: