Braunschweig, 03.08.2009

UltraFast™ Digitally Programmable 5A LDO

85mV Dropout & 25uVRMS Noise

Linear Technology Corporation announces the LT3070, a digitally programmable linear regulator with the lowest dropout voltage, lowest noise and fastest transient response of any monolithic 5A LDO currently available. Dropout voltage at 5A is an ultralow 85mV. Output voltage noise at 5A is only 25uVRMS over a 10Hz to 100kHz bandwidth. The LT3070’s 1MHz unity gain bandwidth, coupled with its minimum 15uF ceramic output capacitance, provides a mere 30mV of overshoot/undershoot in response to a fast 4.5A output load step, saving significant bulk capacitance, space and cost. The LT3070 is ideal for efficiently powering low voltage, high current devices such as FPGAs, DSPs, ASICs, microprocessors, sensitive communication supplies, server/storage devices, and post-buck regulation applications.
The LT3070’s output voltage is digitally programmable from 0.8V to 1.8V in 50mV increments. Accuracy is tightly specified at ±1% over line, load and temperature. A digital margining feature can adjust system output voltage in increments of ±1%, ±3% or ±5%, advantageous during system development debug. A PowerGood flag indicates if output voltage is in regulation or the device is in UVLO and the flag also provides an early warning indication of a thermal fault. The LT3070’s input supply voltage range is 0.95V to 3.0V and its bias supply voltage ranges from 2.2V to 3.6V. The bias supply provides gate drive to the internal NMOS pass device.
Multiple LT3070 devices can be easily paralleled for higher output current and to spread heat across a PCB. A tracking feature can control a buck regulator powering the LT3070’s input. This tracking function drives the upstream buck regulator to maintain the LT3070’s input voltage at VOUT + 300mV, minimizing power dissipation. If output voltage is dynamically changed, the tracking function automatically adjusts the output voltage of the buck regulator to maintain efficiency. Internal protection circuitry includes UVLO, reverse-current protection, precision current limiting with power foldback and thermal shutdown with hysteresis.
The LT3070 is offered in a thermally enhanced, low profile (0.75mm) 28-lead 4mm x 5mm QFN package, and both E and I grades operate from -40°C to +125°C junction temperature range.

Summary of Features: LT3070

Output Current: 5A
Dropout Voltage: 85mV Typical
Digitally Programmable VOUT : 0.8V to 1.8V in 50mV Increments
Digital Output Margining: ±1%, ±3% or ±5%
Low Output Noise: 25uVRMS (10Hz to 100kHz)
Parallelable: Use Two for a 10A Output
Precision Current Limit: ±10%
±1% Accuracy Over Line, Load and Temperature
Stable with Low ESR Ceramic Output Capacitors (15uF Minimum)
High Frequency PSRR: 30dB at 1MHz
Enable Function Turns Output On/Off
VIOC Pin Controls Buck Converter to Maintain Low Power Dissipation and Optimize Efficiency
PWRGD/UVLO Flag
Current Limit with Foldback & Thermal Shutdown with Hysteresis Protection
Low Profile (0.75mm) Thermally Enhanced 28-Lead 4mm x 5mm QFN Package

3070 Pre-release Datasheet
LT3070 Backgrounder
LT3070 Presentation