LM350T 参数 Datasheet PDF下载

LM350

Typical Application

LM350

IN

Input

ADJ

OUT

I

1

R

1

120

C

O

1uF

Output

I

ADJ

C

I

0.1uF

R

2

Figure 13.

C

I

: C

I

is required if the regulator is located an appreciable distance from power supply filter.

C

O

: Output capacitors in the range of 1μF to 100μF of aluminum or tantalum electronic are commonly used to provide

improved output impedance and rejection of transients.

In operation, the LM350 develops a nominal 1.25V reference voltage, V

REF

, between the output and adjustment terminal. The

reference voltage is impressed across program resistor R

1

and, since the voltage is constant, a constant current I

1

then flows

through the output set resistor R

2

, giving an output voltage of

V

O

= 1.25V(1+R

2

/R

1

) + I

ADJ

R

2

Since I

ADJ

current (less than 100μA) from the adjustment terminal represents an error term, the LM350 was designed to

minimize I

ADJ

and make it very constant with line and load changes. To do this, all quiescent operating current is returned to

the output establishing a minimum load current requirement. If there is insufficient load on the output, the output voltage will

rise. Since the LM350 is a floating regulator, it is only the voltage differential across the circuit which is important to

performance, and operation at high voltage with respect to ground is possible.

Since I

ADJ

is controlled to less than 100μA, the error associated with this term is negligible in most applications.

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