POWER AND LINEAR IC SOLUTIONS

Directly Parallelable 1.1A LDO for Modern PCBs

The LT3080 is a 1.1A low noise Low DropOut regulator (LDO) that can accommodate a wide range of input and output voltages and offers tight line and load regulation, high ripple rejection and low external parts count. Unlimited devices can be used in parallel, making it highly suitable for use in modern multiple-rail systems.

The first three-terminal adjustable regulators were introduced in 1976. They used two external resistors that generated an output voltage between 1.2V up to a maximum of 40V.



Featuring good line and load regulation, 300mV dropout, 1.5A output current and a well-controlled current limit that was constant with temperature, these devices represented a major advance over earlier regulators.

Today, designs are constrained by the ability of a surface mount board to dissipate power. This limits attainable output currents. The solution is to use several regulators in parallel, to provide higher current capability and at the same time spread the dissipated power over a larger area.

A further design requirement in modern systems is the need to adjust output voltage to 1.2V and below. New, high performance digital circuits require such low voltages and there is reason to believe that this figure will continue downwards. Even newer generations of LDOs, such as the LT1086, are limited to 1.2V.

Furthermore, surface mount components and high density boards put severe restrictions on the use of heat sinks and wires.

The LT3080 is designed to satisfy such requirements. The device features a wide input voltage capability from 1.2V to 36V (40V absolute maximum) and has a dropout voltage as low as 300mV (two supply operation) at full load, limiting power dissipation and increasing overall system efficiency.

The device’s output voltage is adjustable, spanning a wide range from 0V to 34.7V (single-supply operation), and the on-chip trimmed reference achieves high accuracy of ±1%. Output noise is only 40µV RMS over a wide 10Hz to 100kHz bandwidth.

The device is offered in an eight-lead Mini Small Outline Plastic (MSOP) package (with an exposed pad for better thermal characteristics), a 3mm x 3mm Dual Flat No lead (DFN) package, five-lead TO-220 and a simple-to-use three-lead SOT-223 (Small Outline Transistor) version.

Specification Table

Part No	IOUT	Max VIN (V)	Dropout Voltage (V)	Noise (μVRMS)	IQ	ISD (μA)	Output Voltage (V)	Ability to Parallel	Package
LT3010/H	50mA	80	0.30	100	30μA	<1	Adj, 5	Yes, with op amp	ThinSOT
LT1761	100mA	20	0.30	20	20μA	<1	Adj	Yes, with op amp	ThinSOT
LT1762	150mA	6.5	0.30	20	25μA	<1	Adj, Fixed	Yes, with op amp	MS8
LTC1844	150mA	6.5	0.11	30	40μA	<1	Adj, Fixed	Yes, with op amp	ThinSOT
LT3012/H	250mA/ 200mA	80	0.40	100	40μA	<1	Adj (1.24V to 60V)	Yes, with op amp	DFN-12, TSSOP-16E
LT3013/H	250mA/ 200mA	80	0.40	100	65μA	<1	Adj (1.24V to 60V)	Yes, with op amp	DFN-12, TSSOP-16E
LT1962	300mA	20	0.27	20	30μA	<1	Adj, Fixed	Yes, with op amp	MS8
LT1763	500mA	20	0.30	20	30μA	<1	Adj, Fixed	Yes, with op amp	SO-8
LT3080 *	1.1A	40	0.30**	36	1mA	N/A	Adj (0V to 34.7V)	Yes	DFN, MSOP8-E, TO-220, SOT-223
LT1965	1.1A	20	0.29	40	500µA	N/A	Adj (1.2V to 19.5V)	Yes, with op amp	DFN, MSOP8-E, TO-220, DDPak
LT1963/A	1.5A	20	0.34	40	1mA	<1	Adj, Fixed	Yes, with op amp	DD, T5, SOT-223, SO-8
LT1764/A	3A	20	0.34	40	1mA	<1	Adj, Fixed	Yes, with op amp	DDPak, TO-220

* current-based reference
** two-supply operation

Features

• 1.1A low noise Low DropOut regulator (LDO)
• Unlimited direct parallel operation
• Wide input voltage capability: 1.2V to 36V (40V abs max)
• Dropout voltage as low as 300mV (two-supply operation)
• Output voltage adjustable from 0V to 34.7V (one-supply operation)
• On-chip ±1% reference
• Output noise 40µV RMS, 10Hz to 100kHz
• MSOP, DFN, TO-220 or SOT-223 package

Applications

• High current, all surface mount supply
• High efficiency linear regulator
• Post regulator for switching supplies
• Low parts count variable voltage supply
• Low output-voltage power supplies

For further information, including a copy of the Linear Technology LT3080 Datasheet, please click here