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參數(shù)資料
| 型號(hào)： | IRU1175 |
| 廠商： | International Rectifier |
| 英文描述： | 7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| 中文描述： | 7.5A的超低壓差型正，可調(diào)式穩(wěn)壓器 |
| 文件頁數(shù)： | 5/6頁 |
| 文件大小： | 50K |
| 代理商： | IRU1175 |
IRU1175
2-83
Rev. 1.2
11/29/99
The IRU1175 keeps a constant 1.25V between the
Vsense pin and the Vadj pin. By placing a resistor R1
across these two pins and connecting the Vsense and
Vout pin together, a constant current flows through R1,
adding to the Iadj current and into the R2 resistor pro-
ducing a voltage equal to the (1.25/R1)*R2 + Iadj*R2.
This voltage is then added to the 1.25V to set the output
voltage. This is summarized in the above equation. Since
the minimum load current requirement of the IRU1175 is
10mA, R1 is typically selected to be a 121
resistor so
that it automatically satisfies this condition. Notice that
since the Iadj is typically in the range of 50
μ
A it only
adds a small error to the output voltage and should be
considered when very precise output voltage setting is
required.
Load Regulation
Since the IRU1175 has separate pins for the output (Vout)
and the sense (Vsense), it is ideal for providing true re-
mote sensing of the output voltage at the load. This
means that the voltage drops due to parasitic resistance
such as PCB traces between the regulator and the load
are compensated for using remote sensing. Figure 3
shows a typical application of the IRU1175 with remote
sensing.
Figure 3 - Schematic showing connection for best
load regulation
Stability
The IRU1175 requires the use of an output capacitor as
part of the frequency compensation in order to make the
regulator stable. Typical designs for the microproces-
sor applications use standard electrolytic capacitors with
typical ESR in the range of 50 to 100m
and an output
capacitance of 500 to 1000
μ
F. Fortunately as the ca-
pacitance increases, the ESR decreases resulting in a
fixed RC time constant. The IRU1175 takes advantage
of this phenomena in making the overall regulator loop
stable.
For most applications a minimum of 100
μ
F aluminum
electrolytic capacitor such as Sanyo, MVGX series,
Panasonic FA series as well as the Nichicon PL series
insures both stability and good transient response.
Thermal Design
The IRU1175 incorporates an internal thermal shutdown
that protects the device when the junction temperature
exceeds the allowable maximum junction temperature.
Although this device can operate with junction tempera-
tures in the range of 150
°
C, it is recommended that the
selected heat sink be chosen such that during maxi-
mum continuos load operation the junction temperature
is kept below this number. The example below shows
the steps in selecting the proper surface mount pack-
age.
Assuming, the following conditions:
Vout=2.7V
Vin=3.3V
Vctrl=5V
Iout=2A DC Avg
Calculate the maximum power dissipation using the fol-
lowing equation:
Pd=Iout*(Vin-Vout) + (Iout/60)*(Vctrl - Vout)
Pd=2*(3.3-2.7) + (2/60)*(5-2.7)=1.28 W
Using table below select the proper package and the
amount of copper board needed.
Pkg
Copper
θ
JA
(
°
C/W) Max Pd Max Pd
Area (
Ta=25
°
C
) (
Ta=45
°
C
)
TO-263 1.4"X1.4" 25
TO-263 1.0"X1.0" 30
TO-263 0.7"X0.7" 35
TO-263 Pad Size 45
SO-8
1.0"X1.0"
55
4.4W
3.7W
3.1W
2.4W
2.0W
3.6W
3.0W
2.6W
2.0W
1.63W
Note: Above table is based on the maximum junction
temperature of 135
°
C.
As shown in the above table, any of the two packages
will do the job. For low cost applications the SO-8 pack-
age is recommended.
1175app3-1.0
R1
R2
Vin
Vctrl
RL
IRU1175
Vsense
Adj
Vout
Vctrl
Vin
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| IRU1175CM | 7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| IRU1175CP | 7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| IRU1175CS | 7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| IRU1175CM | 制造商:IRF 制造商全稱:International Rectifier 功能描述:7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| IRU1175CMTR | 功能描述:IC REG LDO ADJ 7.5A TO-263-5 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:4V 輸入電壓:最高 16V 電壓 - 壓降（標(biāo)準(zhǔn)）:0.28V @ 150mA 穩(wěn)壓器數(shù)量:1 電流 - 輸出:150mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:5-VFBGA 供應(yīng)商設(shè)備封裝:5-uSMD 包裝:Digi-Reel® 其它名稱:LP2985AIBP-4.0DKR |
| IRU1175CP | 制造商:IRF 制造商全稱:International Rectifier 功能描述:7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| IRU1175CS | 制造商:IRF 制造商全稱:International Rectifier 功能描述:7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| IRU1176 | 制造商:IRF 制造商全稱:International Rectifier 功能描述:7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR WITH SHUTDOWN INPUT |
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