ILC7080 Просмотр технического описания (PDF) - Impala Linear Corporation

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ILC7080

50/100mA SOT-23 CMOS RF LDO™ Regulators

Impala Linear Corporation 

50/100mA SOT-23 CMOS RF LDO™ Regulators

VIN

CNOISE

BANDGAP

REFERENCE

VREF

INTERNAL VDD

ERROR

AMPLIFIER

TRANS-

CONDUCTANCE

AMPLIFIER

GND

FEEDBACK

VOUT

ON/OFF

Figure 2: ILC7080/81 RF LDO regulator block digram

Shutdown (ON/OFF) Operation

The ILC7080/81 output can be turned off by applying 0.4V

or less to the device’s ON/OFF pin (pin 3). In shutdown

mode, the ILC7080/81 draws less than 1mA quiescent cur-

rent. The output of the ILC7081 is enabled by applying 2V

to 13V at the ON/OFF pin. In applications where the

ILC7080/81 output will always remain enabled, the ON/OFF

pin may be connected to VIN (pin 1). The ILC7080/81’s

shutdown circuitry includes hysteresis, as such the device

will operate properly even if a slow moving signal is applied

to the ON/OFF pin. The device’s shutdown pin includes a

2MΩ internal pull down resistor connected to ground.

Short Circuit Protection

The ILC7080/81 output can withstand momentary short cir-

cuit to ground. Moreover, the regulator can deliver very high

output peak current due to its 1A instantaneous short circuit

current capability.

Adjustable Output Voltage

Figure 3 shows how an adjustable output voltage can be

easily achieved using ILC7080/81-ADJ. The output voltage,

VOUT is given by the following equation:

VOUT = 1.24V x (R1/R2 + 1)

VOUT

COUT

VIN

CIN

R1

R2

5 SOT23-5 4 VADJ

ILC7080-ADJ

ILC7081-ADJ

1

2

3

ON

OFF

Thermal Protection

The ILC7080/81 also includes a thermal protection circuit

which shuts down the regulator when die temperature

exceeds 170°C due to overheating. In thermal shutdown,

once the die temperature cools to below 160°C, the regula-

tor is enabled. If the die temperature is excessive due to

high package power dissipation, the regulator’s thermal cir-

cuit will continue to pulse the regulator on and off. This is

called thermal cycling.

Figure 3: Application circuit for adjustable output voltage

For best results, a resistor value of 470kΩ or less may be

used for R2. The output voltage can be programmed from

2.5V to 12V.

Note: An external capacitor should not be connected to the

adjustable feedback pin (pin 4). Connecting an external capacitor

to pin 4 may cause regulator instability and lead to oscillations.

Excessively high die temperature may occur due to high dif-

ferential voltage across the regulator or high load current or

high ambient temperature or a combination of all three.

Thermal protection protects the regulator from such fault

conditions and is a necessary requirement in today’s

designs. In normal operation, the die temperature should be

limited to under 150°C.

Impala Linear Corporation

ILC7080/81 1.1

(408) 574-3939 www.impalalinear.com

Sept. 1998 6

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