7083A1K データシートの表示（PDF） - Fairchild Semiconductor
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7083A1K Datasheet PDF : 16 Pages
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ILC7083/ILC7084
VIN
CNOISE
BANDGAP
REFERENCE
VREFD
INTERNAL VDD
ERROR
AMPLIFIER
TRANS-
CONDUCTANCE
AMPLIFIER
GND
FEEDBACK
VOUT
ON/OFF
Figure 2. ILC7083 RF LDO Regulator Block Diagram
Shutdown (ON/OFF) Operation
The ILC7083/ILC7084 output can be turned off by applying
0.6V or less to the device’s ON/OFF pin (pin 3). In shutdown
mode, the ILC7083/ILC7084 draws less than 1µA quiescent
current. In shutdown mode the output of ILC7083 is coupled
to a low impedance circuit which discharges the output
capacitor. The output of the ILC7083/ILC7084 is enabled by
applying 1.5V to 13V at the ON/OFF pin. In applications
where the ILC7083 output will always remain enabled, the
ON/OFF pin may be connected to VIN (pin 1). The ILC7083/
ILC7084’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.
Short Circuit Protection
The ILC7083/ILC7084 output can withstand momentary
short circuit to ground. Moreover, the regulator can deliver
very high output peak current due to its 1A instantaneous
short circuit current capability.
Thermal Protection
The ILC7083/ILC7084 also includes a thermal protection
circuit which shuts down the regulator when die temperature
exceeds 150°C due to overheating. In thermal shutdown,
once the die temperature cools to below 140°C, the regulator
is enabled. If the die temperature is excessive due to high
package power dissipation, the regulator’s thermal circuit
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 eas-
ily achieved using ILC7083/ILC7084-ADJ. The output volt-
age, VOUT is given by the following equation:
VOUT = 1.255V x (R1/R2 + 1)
VOUT
R1
R2
5 SOT23-5 4 VADJ
COUT
VIN
CIN
ILC7083-ADJ
or ILC7084-ADJ
1
23
ON
OFF
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 that an external capacitor should not be connected
to the adjustable feedback pin (pin 4). Connecting an
external capacitor to pin 4 may cause regulator instabil-
ity and lead to oscillations.
6
REV. 1.0.9 1/28/03
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