Linear Design Features - LTJournal-V20N2-06-di-LT3070-Kelly_Consoer User Manual
Summary
Designed for high-performance power delivery, the LT3070 and LT3071 are specialized linear regulators featuring ultrafast transient response, ultra-low noise, and low dropout voltage. These devices provide critical Point-of-Load (PoL) power management for demanding electronics, such as FPGAs and microprocessors operating with gigahertz data rates. The accompanying manual serves as a technical guide detailing advanced implementation techniques, including efficient paralleling and unique VIOC control. This resource is intended for electrical engineers designing sensitive server backplanes requiring maximum efficiency and stable power even under extreme current transients.
Page 1 Text Content
Ultrafast, Low Noise, Low Dropout Linear Regulators Running in Parallel Produce Clean, Efficient, High Current Point-of-Load Power for FPGA and Server Backplanes Kelly Consoer
The latest FPGAs and processors have migrated to deep submicron geometries with gigahertz+ data rates and integrated telemetry channels that operate from 0.9V to 1.8V supply rails. The transient power demand for these processors can reach more than 10A peak current in nanoseconds. At these processor speeds and high currents even the local PCB backplane impedances around the processor can contribute to supply droop, where millivolts of supply droop or supply noise can degrade data integrity. To manage the system power distribution, transients. Unfortunately, bulk tantalum The LT3070 and LT3071 family of switching regulators may be used locally and electrolytic caps have parasitic ESL and Ultra Fast™ transient response, low noise, to downconvert from a higher voltage ESR that limits their ability to bypass low dropout linear regulators addresses rail. These regulators are traditionally fast high current load transients. To a this challenge. The high bandwidths of bypassed with a large quantity of bulk lesser extent, even large ceramic caps are the LT3070 and LT3071 reduce the sup- caps to reduce ripple and buffer the load bandwidth limited by their inherent ESL. ply impedance at the point-of-load using
Figure 1. Paralleled LT3070s with VIOC control of upstream LTC3415 switcher implementation
VBIAS
CIN1 PWRGD
100µF 1Ω CBIAS1
0.1µF L1 BIAS
PVINRUNPGOOD TRACKSVIN 0.2µH
EN PWRGD
PHMODE SW IN SENSE
CIN2 OUT 1V
22µF LT3070 COUT1 COUT2 COUT3 3.5A VO0
VO1 RTRACE
PLLLPF 3mΩ
VO2 *X5R OR X7R CAPACITORS
CONTROLLED
MARGTOL
CLKIN
MGN MARGSEL P.O.L. 1
LTC3415
CLKOUT BSEL VIOC REF/BYP
17.4k RREF/BYP1 POWER
1n F GND
1% 0.01µF PLANE
SGND VFB 1V/7A
MODE CBULK
CBIAS2
ITHM 4.7µF
ITH RTRACE
SGND ×2
PGND CONTROLLED
EN PWRGD
IN SENSE
CIN3 OUT 1V
NOTE: LTC3415 SWITCHER, 2MHz INTERNAL OSCILLATOR 22µF LT3070 COUT4 COUT5 COUT6 3.5A
LTC3415 AND LT3070 ×2 ON SAME PCB POWER PLANE 2.2µF* 4.7µF* 10µF*
VO1 VO2 *X5R OR X7R CAPACITORS CBULK: TDK C3225X5ROJ107M MARGTOL
CIN1: TDK C3225X5ROJ107M MARGSEL CIN2’ CIN3: TDK C2012X5R1A226K
COUT1’ COUT4: TDK C2012X5R1A225K VIOC REF/BYP
RREF/BYP1
COUT2’ COUT5: TDK C2012X5R1A475K 1n F GND
COUT3’ COUT6: TDK C2012X5R1A106K
CBIAS1’ CBIAS2: TDK C2012X5R1A475K
L1: IHLP-2525CZ-01 RREF/BYP: GRM155R71E103K ALL RESISTORS ARE 1%, 0402 CASE SIZE, UNLESS OTHERWISE NOTED
28 | July 2010 : LT Journal of Analog Innovation
Page Summary Contents For Linear Design Features - LTJournal-V20N2-06-di-LT3070-Kelly_Consoer User Manual
Manual Details
| Brand | Linear |
|---|---|
| Pages | 2 |
| File Size | 1.21 MB |
| Published | July 22, 2026 |
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Frequently Asked Questions
What problem do high-speed processors pose for power supply?
High transient power demand (over 10A peak in nanoseconds) and local PCB backplane impedances can cause supply droop, degrading data integrity.
How can multiple linear regulators be used together?
Multiple LT3070/LT3071s can be paralleled to share a common load current, increasing the total output capability while maintaining clean power.
What are the key benefits of the LT3070/LT3071 family?
They offer ultrafast transient response and low noise point-of-load regulation for sensitive applications like FPGAs and microprocessors.
Does the LT3070 provide advanced control features?
Yes, it includes digital controls (like VIOC) that allow the user to margin the system output voltage without significant external ballasting.