1. 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

3. Power Business Unit Products:
Switching Regulators, DC/DC Controllers, Charge-Pumps, 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

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 X X X X X X X X

5. LT3070: What is It? UltraFast™ 5A LDO

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

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, ultra- fast transient response regulator with excellent high frequency PSRR performance.

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

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

10. LT3070: 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 post-regulating 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

11. LT3070: Package/Pinout

12. LT3070 Typical Application Circuit
Power Good Indicator
Pin-selectable VOUT
Small Output Caps!!!
Soft Start Control
Digital Margining Select 12

13. LT3070 Post-Buck Regulator Application
1.3V / 7A V
BIAS
3.3V
PGOOD
0.01µF
X7R
OUT
2.2µF
47µF
50K
LOAD 1 W µF
X7R, 0805
100µF, 6.3V
(x3)
PLLLPF
MODE
PHMODE
TRACK
BSEL
MGN L
TC3415EUHF
RUN PV
CLKOUT SV SW
PGND
SGND IN I TH
THM
CLKIN NC FB
0.2µH
6.3V
15K
20K
0.1µF
10pF
100pF
1.0V / 5A
Notes:
TC3415 Switcher 2MHz internal oscillator
PWRGD
VIOC
GND
REF/BYP
VO2
VO1
VO0 EN
SENSE
T3070
MARGTOL
MARGSEL
4.7nF 2K
Optimal Efficiency across LDO
Maintain a constant “VIN – VOUT” across the LDO by adjusting the VITH / VC pin regulation point 13

14. LT3070 Current Sharing Application
Achieve 10A load current capability…or more! 14

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

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