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參數(shù)資料
| 型號： | IRU1176 |
| 廠商： | International Rectifier |
| 英文描述： | 7.5A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR WITH SHUTDOWN INPUT |
| 中文描述： | 7.5A的超低壓差型正面的關(guān)斷輸入可調(diào)調(diào)壓器 |
| 文件頁數(shù)： | 5/6頁 |
| 文件大?。?/td> | 46K |
| 代理商： | IRU1176 |
IRU1176
5
Rev. 1.4
03/18/02
www.irf.com
The IRU1176 keeps a constant 1.25V between the V
SENSE
pin and the V
ADJ
pin. By placing a resistor R1 across
these two pins and connecting the V
SENSE
and V
OUT
pin
together, a constant current flows through R1, adding to
the I
ADJ
current and into the R2 resistor producing a volt-
age equal to the (1.25/R1)
×
R2 + I
ADJ
×
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 IRU1176 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 adds a
small error to the output voltage and should be consid-
ered when very precise output voltage setting is required.
Load Regulation
Since the IRU1176 has separate pins for the output (V
OUT
)
and the sense (V
SENSE
), 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 4
shows a typical application of the IRU1176 with remote
sensing.
Figure 4 - Schematic showing connection
for best load regulation.
Stability
The IRU1176 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 IRU1176 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.
Shutdown Operation
The IRU1176 can be disabled by pulling the SD pin low
using an open collector device such as a low cost 2N3904
general purpose transistor as shown in the application
circuit. The current sink of the pin is equal to:
Thermal Design
The IRU1176 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 continuous load operation the junction tempera-
ture is kept below this number. The example below
shows the steps in selecting the proper surface mount
package.
Assuming, the following conditions:
V
OUT
= 2.7V
V
IN
= 3.3V
V
CTRL
= 5V
I
OUT
= 2A (DC Avg)
Calculate the maximum power dissipation using the fol-
lowing equation:
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
(
T
A
=25
°
C
) (
T
A
=45
°
C
)
M or P 1.4"X1.4" 25
M or P 1.0"X1.0" 30
M or P 0.7"X0.7" 35
M or P Pad Size 45
4.4W
3.7W
3.1W
2.4W
3.6W
3.0W
2.6W
2.0W
Note:
Above table is based on the maximum junction
temperature of 135
8
C.
As shown in the above table, any of the two packages
will do the job. For lower cost applications the Ultra Thin-
Pak package is recommended.
P
D
= 2
×
(3.3 - 2.7) +
o
p
×
(5 - 2.7) = 1.28W
60
2
P
D
= I
OUT
×
(V
IN
- V
OUT
) +
o
p
×
(V
CTRL
- V
OUT
)
60
I
OUT
I
SINK
= (V
Typically
R
CTRL
- 1.4)
R1
R2
V
IN
V
CTRL
R
L
IRU1176
V
SENSE
Adj
V
OUT
V
CTRL
V
IN
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| IRU1176CM | 功能描述:IC REG LDO ADJ 7.5A TO-263-7 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 |
| IRU1176CMTR | 功能描述:IC REG LDO ADJ 7.5A TO-263-7 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（最小）:- 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 |
| IRU1176CP | 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 |
| IRU1176CPTR | 功能描述:IC REG LDO ADJ 7.5A 7-UTHINPAK 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 |
| IRU1205 | 制造商:IRF 制造商全稱:International Rectifier 功能描述:300mA ULTRA LOW DROPOUT POSITIVE ADJUSTABLE AND FIXED REGULATORS |
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