UltraFast™ Digitally Programmable 5A LDO Features Analog Margining, Output Current Monitor, 85mV Dropout & 25µVRMS Noise
Linear Technology Corporation announces the LT3071, the second in a family of digitally programmable linear regulators 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 25µVRMS over a 10Hz to 100kHz bandwidth. The LT3071's 1MHz unity gain bandwidth, coupled with its minimum 15µF 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 LT3071 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 LT3071'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. An analog output margining feature can adjust system output voltage over a continuous ±10% range, advantageous during system development debug. A PowerGood flag indicates if output voltage is in regulation or if the device is in UVLO, and the flag also provides an early warning indication of a thermal fault. An output current monitor sources a scaled dynamic representation of output current (IOUT/2500) that can be measured directly or terminated with a resistor and converted to voltage, allowing load conditions or power to be calculated. The LT3071'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 LT3071 devices can be easily paralleled for higher output current and to spread heat across a circuit board. A tracking feature can control a buck regulator powering the LT3071's input. This tracking function drives the upstream buck regulator to maintain the LT3071'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 LT3071 is offered in a thermally enhanced, low profile (0.75mm) 28-lead 4mm × 5mm QFN package, and both E and I grades operate from –40ºC to +125ºC junction temperature range. 1,000-piece pricing starts at $4.20 and $4.80 each, respectively. For more information, visit www.linear.com.
Summary Features LT3071
- Output Current: 5A
- Dropout Voltage: 85mV Typical
- Digitally Programmable VOUT: 0.8V to 1.8V in 50mV Increments
- Analog Output Margining: ±10% Range
- Output Current Monitor: Sources IOUT/2500, 2mA at IOUT=5A
- Low Output Noise: 25µVRMS (10Hz to 100kHz)
- Parallelable: Use Two for a 10A Output
- Precision Current Limit: ±20%
- ±1% Accuracy Over Line, Load and Temperature
- Stable with Low ESR Ceramic Output Capacitors (15µF Minimum)
- High Frequency PSRR: 30dB at 1MHz
- Enable Function Turns Output On/Off
- VIOC Pin Controls Buck Converter to Maintain Low Power Dissipation & Optimize Efficiency
- PWRGD/UVLO/Thermal Shutdown Flag
- Current Limit with Foldback Protection
- Thermal Shutdown
- Low Profile (0.75mm) Thermally Enhanced 28-Lead 4mm × 5mm QFN Package
UltraFast, Digitally Programmable Ultralow Dropout, Low Noise 5A LDO with Analog Margining
Editor's Contact Information
- Doug Dickinson