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Linear Technology Corporation LT3070 Backgrounder Steve Knoth Senior Product Marketing Engineer 2 Agenda Background • Past Limitations for LDOs Powering FPGAs/ASICs • Advantages of Next Gen Linear Tech LDOs LT3070 • Definition • Features & Benefits • Application Circuits • Target Markets • Target Applications © 2006 Linear Technology 3 Power Business Unit • Products: – Switching Regulators, DC/DC Controllers, ChargePumps, Linear Regulators, Battery Chargers, PMICs, LED Drivers, DC Power Switches • Markets: Handheld Battery Powered Products – Cell Phones, Digital Still Cameras, PDAs, MP3 Players, PNDs, etc. Industrial Control and Instrumentation Automotive – Navigation and Infotainment Telecommunications – Infrastructure Computer – Servers, Workstations and Notebook PC © 2006 Linear Technology 4 Traditional Limitations for in Powering FPGAs/DSPs/ASICs/µPs For high-performance digital ICs such as FPGAs, DSPs, µP’s, µC’s and ASICs, the trend is for higher currents and lower voltages. More efficient, switching regulators have traditionally been used to power these devices but there are noise and layout limitations, so LDOs have come into play. • • • • • • • • The LDO must have: Operation over a wide input/output voltage range High output current capability Low output noise Low dropout operation Excellent thermal performance Fast response time High PSRR System debugging features a “+” plus © 2006 Linear Technology X X X X X X X X 5 LT3070: What is It? UltraFast™ 5A LDO © 2006 Linear Technology 6 LT3070: What is It? UltraFast 5A LDO 5A, Low Noise, Programmable Output, 85mV Dropout Linear Regulator • New NMOS LDO Family: Low Noise, Programmable Output, High BW • Wide VIN Range: 0.95V to 3V • Ultra-Low Output Voltage Noise: 25µVRMS (10Hz to 100kHz) • Wide VOUT Range: 0.8V to 1.8V in 50mV increments • Fast Transient Response • Digital Margining for System Debug © 2006 Linear Technology 7 LT3070: Block Diagram The LT3070’s architecture drives an internal N-channel power MOSFET as a source follower. This configuration permits a user to realize an extremely low dropout, ultrafast transient response regulator with excellent high frequency PSRR performance. © 2006 Linear Technology 8 LT3070: Key Technical Features * • • • • • • • • Output Current: 5A Dropout Voltage: 85mV Typical Digitally Programmable VOUT: 0.8V to 1.8V in 50mV steps Digital Output Margining: ±1%, ±3% or ±5% ±1% Accuracy Over Line, Load and Temperature (Initial = 0.2%) Low Output Noise: 25μVRMS (10Hz to 100kHz) Parallelable: Use Two for a 10A Output 28-Lead (4mm × 5mm) QFN Package * Specifications subject to change © 2006 Linear Technology 9 LT3070: Other Features * • Stable with Low ESR Ceramic Output Capacitors (15μF Min) • High Frequency PSRR: 30dB at 1MHz • VIOC Pin Controls Upstream Buck Converter to Maintain Low Power Dissipation and Optimize Efficiency • PWRGD/UVLO Flag • REF/BYP Pin: Single Cap provides programmable soft-start and lowers output noise • Enable Function Turns Output On/Off • Current Limit Foldback Protection • Thermal Shutdown * Specifications subject to change © 2006 Linear Technology 10 LT3070: Features & Benefits FEATURES BENEFITS Ultra-Low Dropout Voltage: 85mV High efficiency, low Vin to low Vout conversion, reduces power dissipation Ultra-Low Noise: 25µVRMS (10Hz to 100kHz) Great for powering noise-sensitive supply rails or for postregulating switchers Digitally Programmable Vout: 0.8V to 1.8V in 50mV increments Precision output voltage set capability Digital Margining: ±1%, ±3%, ±5% Helpful to determine system tolerance during debug phase Wide Input Voltage Range: 1V to 3V Flexibility, penetration into a wide variety of end markets/applications 2 Devices May be Paralleled (10A) Higher-current capability than a single LDO can provide; spreads heat across a PCB Fast Transient Response Maintains output voltage stability during fast events Reverse Current Protection, Current Limit with Power Foldback, Thermal Shutdown, UVLO Bulletproof protection for the IC and the load Thermally Efficient Package: 4mmx5mm QFN-28, ThetaJA=30°C/W Small package provides plenty of current in a small footprint with great thermal performance © 2006 Linear Technology 11 LT3070: Package/Pinout © 2006 Linear Technology 12 LT3070 Typical Application Circuit Power Good Indicator Pin-selectable VOUT Small Output Caps!!! Soft Start Control Digital Margining Select © 2006 Linear Technology 13 LT3070 Post-Buck Regulator Application VBIAS 3.3V SGND 1W 47µF 6.3V (x3) 2.2µF 100pF 50K 50K 0.1µF PGOOD CLKOUTRUN PVIN PVIN SVIN ITHM ITH NC NC 100pF 10pF IN 47µF VFB VO2 PVIN PVIN NC VO1 PVIN PVIN PLLLPF SENSE EN 15K TRACK SGND 15K BIAS 20K LT3070 NC MARGTOL SW NC MARGSEL SW SW VIOC SW SW MODE PGND PGOOD CLKIN BSEL PHMODE MGN 0.2µH Optimal Efficiency across LDO 1.3V / 7A Notes: LTC3415 Switcher 2MHz internal oscillator Maintain a constant “VIN – VOUT” across the LDO by adjusting the VITH / VC pin regulation point © 2006 Linear Technology 0.01µF X7R 4.7nF PGNDPGNDPGNDPGNDPGNDPGNDPGND 100µF, 6.3V (x3) REF/BYP GND 2K LOAD 2.2 + 4.7 + 10µF X7R, 0805 NC VO0 SW T LC3415EUHF VOUT 1.0V / 5A PWRGD SW SW OUT 14 LT3070 Current Sharing Application Achieve 10A load current capability…or more! © 2006 Linear Technology 15 LT3070: Typical Applications/Target End Markets • FPGA and DSP Supplies • ASIC and Microprocessor Supplies • Servers and Storage Devices • Sensitive Communication Supplies • Supply Isolation • Post Buck Regulation © 2006 Linear Technology 16 © 2006 Linear Technology 17 LT3070: Conclusion • Requirements for LDOs Powering High Performance Digital ICs: • Operation over a wide input/output voltage range with high output current capability • Low output noise • Low dropout operation • Excellent thermal performance • Fast response time and high PSRR • System debugging features a “+” plus LT3070 UltraFast 5A Ultra-Low Dropout, Low Noise LDO: • Dropout Voltage: 85mV Typical • Digitally Programmable VOUT: 0.8V to 1.8V • Digital Output Margining: ±1%, ±3% or ±5% • ±1% Accuracy Over Line, Load and Temperature • Low Output Noise: 25μVRMS (10Hz to 100kHz) • Parallelable: Use Two for a 10A Output • 28-Lead (4mm × 5mm) QFN Package © 2006 Linear Technology