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69190-405

150mA SOT-23 Ultra Low Noise CMOS RF-LDO™ Regulator

Impala Linear Corporation 

150mA SOT-23 Ultra Low Noise CMOS RF-LDO™ Regulator

ELECTRICAL CHARACTERISTICS ILC7082AIM5 (continued)

Shutdown (ON/OFF) Operation

The ILC7082 output can be turned off by applying 0.4V or

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

the ILC7082 draws less than 1mA quiescent current. The

output of the ILC7081 is enabled by applying 1.5V to 13V at

the ON/OFF pin. In applications were the ILC7082 output

will always remain enabled, the ON/OFF pin may be con-

nected to VIN (pin 1). The ILC7082’s shutdown circuitry

includes hysteresis, as such the device will operate proper-

ly even if a slow moving signal is applied to the ON/OFF pin.

The device’s shutdown pin includes a 2MW internal pull

down resistor connected to ground.

Short Circuit Protection

The ILC7082 output can withstand momentary short circuit

to ground. Moreover, the regulator can deliver very high out-

put peak current due to its 1A instantaneous short circuit

current capability.

Thermal Protection

The ILC7082 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.

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.

Adjustable Output Voltage

Figure 5 shows how an adjustable output voltage can be

easily achieved using ILC7082-Adj. The output voltage,

VOUT is given by the following equation:

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

VOUT

R1

R2

5 SOT23-5 4 VADJ

COUT

VIN

CIN

ILC7082-ADJ

1

23

ON

OFF

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

used for R2. The output voltage can be programmed from

2.5V to 12V.

Note that an external capacitor should not be connect-

ed to the adjustable feedback pin (pin 4). Connecting

an external capacitor to pin 4 may cause regulator

instability and lead to oscillations.

Maximum Output Current

The maximum output current available from the ILC7082 is

limited by the maximum package power dissipation as well

as the device’s internal current limit. For a given ambient

temperature, TA, the maximum package power dissipation

is given by:

PD(MAX) = (TJ(MAX) - TA) / θJA

where TJ(MAX) = 150°C is the maximum junction temperature

and θJA = 333°C/W is the package thermal resistance. For

example at TA = 85°C ambient temperature, the maximum

package power dissipation is;

PD(MAX) = 195mW.

The maximum output current can be calculated from the fol-

lowing equation:

IOUT(MAX) < PD(MAX) / (VIN - VOUT)

For example at VIN = 6V, VOUT = 5V and TA = 85°C, the max-

imum output current is IOUT(MAX) < 195mA. At higher output

current, the die temperature will rise and cause the thermal

protection circuit to be enabled.

APPLICATION HINTS

Figure 4 shows the typical application circuit for the ILC7082.

VOUT

COUT

5 SOT23-5 4

ILC7082

CNOISE

VIN

1

CIN

23

ON

OFF

Figure 4: Basic application circuit for fixed

output voltage versions

Fig. 3: Application circuit for adjustable output voltage

Impala Linear Corporation

ILC7082 1.3

(408) 574-3939

www.impalalinear.com

April 1999 6

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