LM1085T-ADJ datasheet, PDF - EEWORLD Datasheet

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LM1085T-ADJ: DescriptionOutput type: Adjustable Maximum input voltage: 15V Output current: 3A Output voltage (minimum value/fixed value): 1.25V; CategoryPower/power management Low dropout linear regulator (they); File Size720KB，5 Pages; ManufacturerGuangdong Huaguan Semiconductor Co., Ltd.; Websitehttp://www.hgsemi.net/; Guangdong Huaguan Semiconductor Co., Ltd. was established in 2011. It is a quasi-high-tech enterprise specializing in the research and development, packaging, testing and sales of semiconductor devices. The company has an internationally advanced level of semiconductor discrete devices and integrated circuit packaging and testing production lines, and a technical team with rich experience in the design, packaging and testing of semiconductor devices. It has established long-term strategic cooperative relations with first-class companies in the same industry, and has formed a professional technical development team to engage in the development of new products and new technologies. The company's R&D project products include power management, operational amplifiers, audio amplifiers, interfaces and drivers, logic devices, memory, time base and clock, data acquisition, MOSFT and special circuits, which are mainly used in automotive electronics, instrumentation, network communications, industrial automation, LED lighting, switching power supplies, smart home appliances, gold card projects, smart transportation and other fields. Huaguan products are positioned as high-end quality, and have been well received by users in recent years. It is currently a high-end quality brand in the industry; HGSEMI&HGC is Huaguan's own brand. The establishment of an independent brand is more conducive to our service to customers, promoting the development of the company, and becoming a leading manufacturer in China's semiconductor industry.

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LM1085T-ADJ Overview

Output type: Adjustable Maximum input voltage: 15V Output current: 3A Output voltage (minimum value/fixed value): 1.25V

LM1085T-ADJ Parametric

Parameter Name	Attribute value
Output type	Adjustable
Maximum input voltage	15V
Output current	3A
Output configuration	just
Number of voltage regulators	1
Output voltage (maximum)	-
PSRR/ripple suppression	65dB ~ 60dB(120Hz)
Output voltage (minimum/fixed value)	1.25V
Pressure drop (maximum)	1.5V @ 3A
Operating power current (maximum)	7mA
Operating temperature	-40℃ ~ 125℃

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LM1085

LOW DROPOUT POSITIVE VOLTAGE REGULATOR

DESCRIPTION

The LM1085 series of positive adjustable and fixed regulators are designed to provide 3A with high efficiency. All internal

circuitry is designed to operate down to 1.3V input to output differential. On-chip trimming adjusts the reference voltage to

1%.

APPLICATIONS



High Efficiency Linear Regulators

Post Regulators for Switching Supplies

Adjustable Power Supply

FEATURES



Adjustable or Fixed Output

Output Current of 3A

Low Dropout, 1.5V max at 3A Output Current

0.04% Line Regulation

0.2 % Load Regulation

100% Thermal Limit Burn-In

Fast Transient Response



TYPICAL APPLICATION DATA

4.8V

4.95V

LM1085-3.3

AMS1085

LM1085

PIN DESCRIPTION

http://www.hgsemi.com.cn

2019 JUN

LM1085

for an output capacitor increases. The value of 22µF tantalum or 150µF aluminum covers all cases of bypassing the

adjustment terminal. Without bypassing the adjustment terminal smaller capacitors can be used with equally good results.

To ensure good transient response with heavy load current changes capacitor values on the order of 100µF are used in the

output of many regulators. To further improve stability and transient response of these devices larger values of output

capacitor can be used.

PROTECTION DIODES

Unlike older regulators, the LM1085 family does not need any protection diodes

between the adjustment pin and the output and from the output to the input to

prevent over-stressing the die.

Internal resistors are limiting the internal current paths on the LM1085 adjustment

pin, therefore even with capacitors on the adjustment pin no protection diode is

needed to ensure device safety under short-circuit conditions.

Diodes between the input and output are not usually needed.

Microsecond surge currents of 50A to 100A can be handled by the internal diode between the input and output pins of the

device. In normal operations it is difficult to get those values of surge currents even with the use of large output

capacitances. If high value output capacitors are used, such as 1000µF to 5000µF and the input pin is instantaneously

shorted to ground, damage can occur. A diode from output to input is recommended, when a crowbar circuit at the input of

the LM1085 is used. Normal power supply cycling or even plugging and unplugging in the system will not generate current

large enough to do any damage.

The adjustment pin can be driven on a transient basis ±25V, with respect to the output without any device degradation. As

with any IC regulator, none the protection circuitry will be functional and the internal transistors will break down if the

maximum input to output voltage differential is exceeded.

LM1085

RIPPLE REJECTION

The ripple rejection values are measured with the adjustment pin bypassed. The impedance of the adjust pin capacitor at the

ripple frequency should be less than the value of R1 (normally 100 to 120) for a proper bypassing and ripple rejection

approaching the values shown. The size of the required adjust pin capacitor is a function of the input ripple frequency. If

R1=100

at 120Hz the adjust pin capacitor should be 25µF. At 10

kHz only 0.22

µF is needed.

The ripple rejection will be a function of output voltage, in circuits without an adjust pin bypass capacitor. The output ripple

will increase directly as a ratio of the output voltage to the reference voltage (V

OUT

/ V

REF

OUTPUT VOLTAGE

LM1085

The LM1085 series develops a 1.25V reference voltage between the output and

the adjust terminal. Placing a resistor between these two terminals causes a

constant current to flow through R1 and down through R2 to set the overall output

voltage.

This current is normally the specified minimum load current of 10mA. Because I

ADJ

is very small and constant it represents a small error and it can usually be ignored.

LOAD REGULATION

LM1085

True remote load sensing it is not possible to provide, because the LM1085 is a

three terminal device. The resistance of the wire connecting the regulator to the

load will limit the load regulation.

The data sheet specification for load regulation is measured at the bottom of the

package. Negative side sensing is a true Kelvin connection, with the bottom of the

output divider returned to the negative side of the load.

The best load regulation is obtained when the top of the resistor divider R1 is

connected directly to the case not to the load. If R1 were connected to the load, the

effective resistance between the regulator and the load would be:

http://www.hgsemi.com.cn

2019 JUN

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