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參數資料
| 型號： | FAN2558MPX |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | 180mA Low Voltage CMOS LDO |
| 中文描述： | 1 V-5.5 V ADJUSTABLE POSITIVE LDO REGULATOR, DSO6 |
| 封裝： | 2 X 2 MM, MLP-6 |
| 文件頁數： | 7/15頁 |
| 文件大小： | 307K |
| 代理商： | FAN2558MPX |
PRODUCT SPECIFICATIONS
FAN2558/FAN2559
REV. 1.0.4 3/15/04
7
Control Functions
Enable Pin
Connecting 2V or greater to the Enable pin will enable the
output, while 0.4V or less will disable it while reducing the
quiescent current consumption to less than 1μA. If this shut-
down function is not needed, the pin can simply be con-
nected permanently to the V
IN
pin. Allowing this pin to
fl
oat
will cause erratic operation.
Error Flag (Power Good)
Fault conditions such as input voltage dropout (low V
IN
),
overheating, or overloading (excessive output current), will
set an error
fl
ag. The PG pin which is an open-drain output,
will go LOW when V
OUT
is less than 95% or the speci
fi
ed
output voltage. When the voltage at V
OUT
is greater than
95% of the speci
fi
ed output voltage, the PG pin is HIGH. A
logic pull-up resistor of 47K
is recommended at this out-
put. The pin can be left disconnected if unused.
Thermal Protection
The FAN2558/FAN2559 is designed to supply high peak
output currents for brief periods, however sustained exces-
sive output load at high input - output voltage difference will
increase the device’s temperature and exceed maximum rat-
ings due to power dissipation. During output overload condi-
tions, when the die temperature exceeds the shutdown limit
temperature of 150°C, an onboard thermal protection will
disable the output until the temperature drops approximately
10°C below the limit, at which point the output is re-enabled.
During a thermal shutdown, the user may assert the power-
down function at the Enable pin, reducing power consump-
tion to a minimum.
Thermal Characteristics
The FAN2558/FAN2559 is designed to supply 180mA at the
speci
fi
ed output voltage with an operating die (junction)
temperature of up to 125°C. Once the power dissipation and
thermal resistance is known, the maximum junction tempera-
ture of the device can be calculated. While the power dissipa-
tion is calculated from known electrical parameters, the
actual thermal resistance depends on the thermal characteris-
tics of the SOT23-5 surface-mount package and the sur-
rounding PC board copper to which it is mounted.
The power dissipation is equal to the product of the input-to-
output voltage differential and the output current plus the
ground current multiplied by the input voltage,
or:
The ground pin current I
GND
can be found in the charts
provided in the Electrical Characteristics section.
The relationship describing the thermal behavior of the
package is:
where T
J(max)
is the maximum allowable junction tempera-
ture of the die, which is 125°C, and T
A
is the ambient operat-
ing temperature.
θ
JA
is dependent on the surrounding PC
board layout and can be empirically obtained. While the
θ
JC
(junction-to-case) of the SOT23-5 package is speci
fi
ed at
130°C /W, the
θ
JA
of the minimum PWB footprint will be at
least 235°C /W. This can be improved by providing a heat
sink of surrounding copper ground on the PWB. Depending
on the size of the copper area, the resulting
θ
JA
can range
from approximately 180°C /W for one square inch to nearly
130°C /W for 4 square inches. The addition of backside cop-
per with through-holes, stiffeners, and other enhancements
can also aid in reducing thermal resistance. The heat contrib-
uted by the dissipation of other devices located nearby must
be included in the design considerations. Once the limiting
parameters in these two relationships have been determined,
the design can be modi
fi
ed to ensure that the device remains
within speci
fi
ed operating conditions. If overload conditions
are not considered, it is possible for the device to enter a
thermal cycling loop, in which the circuit enters a shutdown
condition, cools, re-enables, and then again overheats and
shuts down repeatedly due to an unmanaged fault condition.
Adjustable Version
The FAN2558ADJ includes an input pin ADJ which allows
the user to select an output voltage ranging from 1V to near
V
IN
, using an external resistor divider. The voltage V
ADJ
pre-
sented to the ADJ pin is fed to the onboard error ampli
fi
er
which adjusts the output voltage until V
ADJ
is equal to the
onboard bandgap reference voltage of 1.00V(typ). The equa-
tion is:
Since the bandgap reference voltage is trimmed, 1% initial
accuracy can be achieved. The total value of the resistor
chain should not exceed 250KOhm total to keep the error
ampli
fi
er biased during no-load conditions. Programming
output voltages very near V
IN
need to allow for the magni-
tude and variation of the dropout voltage V
DO
over load, sup-
ply, and temperature variations. Note that the low-leakage
FET input to the CMOS error ampli
fi
er induces no bias
current error to the calculation.
P
D
V
IN
V
OUT
–
(
)
I
OUT
V
IN
I
GND
×
+
×
=
P
D max
)
T
-------------------------------
T
A
–
JA
=
V
OUT
0.59V
1
R
1
R
2
-----
+
×
=
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相關代理商/技術參數 |
參數描述 |
|---|---|
| FAN2558S10X | 功能描述:低壓差穩壓器 - LDO 180ma LV CMOS LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節:0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| FAN2558S12X | 功能描述:低壓差穩壓器 - LDO 180ma LV CMOS LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節:0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| FAN2558S12X | 制造商:Fairchild Semiconductor Corporation 功能描述:IC LDO VOLT REG 1.2V 180mA 5-SOT-23 |
| FAN2558S12X_NL | 功能描述:低壓差穩壓器 - LDO 180ma LV CMOS LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節:0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| FAN2558S12X_Q | 功能描述:低壓差穩壓器 - LDO 180ma LV CMOS LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節:0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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