LT3030HFE-PBF 데이터 시트보기 (PDF) - Linear Technology

부품명

상세내역

일치하는 목록

LT3030HFE-PBF

Dual 750mA/250mA Low Dropout, Low Noise, Micropower Linear Regulator

Linear Technology 

LT3030

Applications Information

The maximum junction temperature then equals the maxi-

mum ambient temperature plus the maximum junction

temperature rise above ambient temperature, or:

TJMAX = 50°C + 24.6°C = 74.6°C

Protection Features

The LT3030 regulator incorporates several protection fea-

tures that make it ideal for use in battery-powered circuits.

In addition to the normal protection features associated with

monolithic regulators, such as current limiting and thermal

limiting, the device protects itself against reverse input volt-

ages and reverse voltages from output to input. The two

regulators have independent inputs, a common GND pin

and are thermally coupled. However, the two channels of

the LT3030 operate independently. Each channel’s output

can be shut down independently, and a fault condition on

one output does not affect the other output electrically,

unless the thermal shutdown circuitry is activated.

Current limit protection and thermal overload protection

protect the device against current overload conditions at

each output of the LT3030. For normal operation, do not

allow the junction temperature to exceed 125°C (LT3030E/

LT3030I) or 150°C (LT3030H/LT3030MP). The typical

thermal shutdown temperature threshold is 165°C and

the circuitry incorporates approximately 5°C of hysteresis.

Each channel’s input withstands reverse voltages of 22V.

Current flow into the device is limited to less than 1mA

(typically less than 100μA) and no negative voltage appears

at the respective channel’s output. The device protects

both itself and the load against batteries that are plugged

in backwards.

The LT3030 incurs no damage if either channel’s output

is pulled below ground. If the input is left open-circuit,

or grounded, the output can be pulled below ground by

22V. The output acts like an open circuit, and no current

flows from the output. However, current flows in (but is

limited by) the external resistor divider that sets the output

voltage. If the input is powered by a voltage source, the

output sources current equal to its current limit capabil-

ity and the LT3030 protects itself by its thermal limiting

circuitry. In this case, grounding the relevant SHDN1 or

SHDN2 pin turns off its channel’s output and stops that

output from sourcing current.

The LT3030 incurs no damage if either ADJ pin is pulled

above or below ground by 9V. If the input is left open

circuit or grounded, the ADJ pins perform like an open

circuit down to –1.5V, and then like a 1.2k resistor down

to –9V when pulled below ground. When pulled above

ground, the ADJ pins perform like an open circuit up to

0.5V, then like a 5.7k resistor up to 3V, then like a 1.8k

resistor up to 9V.

In situations where an ADJ pin connects to a resistor divider

that would pull the pin above its 9V clamp voltage if the

output is pulled high, the ADJ pin input current must be

limited to less than 5mA. For example, assume a resistor

divider sets the regulated output voltage to 1.5V, and the

output is forced to 20V. The top resistor of the resistor

divider must be chosen to limit the current into the ADJ

pin to less than 5mA when the ADJ pin is at 9V. The 11V

difference between the OUT and ADJ pins divided by the

5mA maximum current into the ADJ pin yields a minimum

top resistor value of 2.2k.

In circuits where a backup battery is required, several

different input/output conditions can occur. The output

voltage may be held up while the input is either pulled

to ground, pulled to some intermediate voltage or is left

open-circuit. Current flow back into the output follows the

curve shown in Figure 5.

If either of the LT3030’s IN pins is forced below its cor-

responding OUT pin, or the OUT pin is pulled above its

corresponding IN pin, input current for that channel typically

5.0

4.5

TJ = 25°C

VIN1 = VIN2 = 0V

4.0

VADJ1 = VOUT1

VADJ2 = VOUT2

3.5

3.0

2.5

IADJ1 OR IADJ2

2.0

1.5

1.0

0.5

IOUT1 OR IOUT2

0

0123456789

OUTPUT VOLTAGE (V)

3030 F05

IADJ = FLOWS INTO ADJ PIN TO GND PIN

IOUT = FLOWS INTO OUT PIN TO IN PIN

Figure 5. Reverse Output Current

3030fa

16

For more information www.linear.com/LT3030

Share Link: