Final Electrical Specifications LTC1504 500mA Low Voltage Step-Down Synchronous Switching Regulator DESCRIPTION FEATURES n 500mA Output Current at 3.3V Output The LTC 1504 is a self-contained, high efficiency syn- n Up to 92% Peak Efficiency chronous buck switching regulator. It includes a pair of n Internal Reference Trimmed to 1% on-chip 1.5 power switches, enabling it to supply up to n Output Can Source or Sink Current 500mA of load current. Efficiency peaks at 92%, minimiz- n Requires as Few as Four External Components ing heat and wasted power. The synchronous buck archi- n Input Voltage Range: 4V to 10V tecture allows the output to source or sink current as n Adjustable Current Limit required to keep the output voltage in regulation. n Small SO-8 Package The LTC1504 is available in adjustable and fixed 3.3V n 200kHz Switching Frequency Can be output versions. An adjustable current limit circuit pro- Synchronized Up to 500kHz vides protection from overloads. The internal 1% refer- U ence combined with a sophisticated voltage feedback loop APPLICATIONS provides optimum output voltage accuracy and fast load transient response. The LTC1504 is specified to operate n Small Portable Digital Systems Daisy-Chained Control Outputs with input voltages between 4V and 10V. Contact the LTC n Active Termination factory for guaranteed specifications at 2.7V supply. n Auxiliary Output Voltage Supplies n Minimum Part Count/Size Switchers The LTC1504 is available in a plastic SO-8 package. , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATION Minimum Part Count 5V to 3.3V Regulator 5V to 3.3V Efficiency 100 NC SHUTDOWN 90 I SHDN MAX 80 L EXT 3.3V AT 500mA 5V V SW CC 70 + LTC1504-3.3 C IN 60 GND SENSE 50 + SS COMP C OUT 40 30 NC 1000pF C : AVX TPSC226M016R0375 IN C : AVX TAJC476M010 20 OUT L : COILTRONICS CTX50-1P EXT 1504 TA01 10 0 10 100 500 LOAD CURRENT (mA) 1504 TA02 Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 1 EFFICIENCY (%) U ULTC1504 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER I FOR ATIO (Note 1) ORDER PART TOP VIEW Supply Voltage (V to GND)................................... 10V CC NUMBER Peak Output Current (SW) ....................................... 1A I 1 8 COMP MAX Input Voltage (All Other Pins) ......... 0.3V to V + 0.3V V 2 7 SS CC CC LTC1504CS8 Operating Temperature Range ..................... 0C to 70C SW 3 6 SHDN LTC1504CS8-3.3 Storage Temperature Range ................. 65C to 150C GND FB/SENSE* 4 5 Lead Temperature (Soldering, 10 sec).................. 300C S8 PACKAGE S8 PART MARKING 8-LEAD PLASTIC SO *FB FOR LTC1504CS8, SENSE FOR LTC1504CS8-3.3 1504 T = 115C, = 90C/W 15043 JMAX JA Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS V = 5V, T = 25C unless otherwise specified. (Note 2) CC A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Minimum Supply Voltage (Note 7) l4V CC V Feedback Voltage LTC1504CS8 l 1.25 1.265 1.28 V FB V Feedback Voltage PSRR Figure 1, 4V V 10V, LTC1504CS8 l 1.1 1.6 % FB CC V Sense Pin Voltage LTC1504CS8-3.3 l 3.20 3.30 3.40 V SENSE V Sense Voltage PSRR Figure 1, 4V V 10V, LTC1504CS8-3.3 l 1.2 1.8 % SENSE CC I Supply Current Figure 1, V = V , I = 0 (Note 4) 3 mA CC SHDN CC OUT Figure 1, V = V , I = 0, V /V = V (Note 4) l 0.3 0.6 mA SHDN CC OUT FB SENSE CC V = 0V l 1.0 20 A SHDN f Internal Oscillator Frequency l 150 200 250 kHz OSC R Internal Switch Resistance l 1.3 2.0 SW V SHDN Input High Voltage l 2.4 V IH V SHDN Input Low Voltage l 0.8 V IL I SHDN Input Current l 0.1 1 A IN V Error Amplifier Positive Swing Figure 2 l 4.5 4.95 V OH V Error Amplifier Negative Swing Figure 2 l 0.05 0.5 V OL I , I Error Amplifier Output Current Figure 2 l 50 100 200 A OH OL g Error Amplifier Transconductance (Note 5) l 350 600 1100 mho mV A Error Amplifier DC Gain (Note 5) l 40 48 dB V g I Amplifier Transconductance (Note 6) 1000 2000 3000 mho mI LIM I I Sink Current V = V l 812 16 A MAX MAX IMAX CC I Soft Start Source Current V = 0V l 8 12 16 A SS SS t , t Output Switch Rise/Fall Time l 550 ns r f DC Maximum Duty Cycle V = V l 84 90 % MAX COMP CC 2 U WU U WWW