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參數(shù)資料
| 型號： | LMS8117AMPX-ADJ |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | 1A Low-Dropout Linear Regulator |
| 中文描述： | 1.25 V-13.8 V ADJUSTABLE POSITIVE LDO REGULATOR, 1.25 V DROPOUT, PDSO4 |
| 封裝： | SOT-223, 3 PIN |
| 文件頁數(shù)： | 9/16頁 |
| 文件大?。?/td> | 777K |
| 代理商： | LMS8117AMPX-ADJ |
Application Note
(Continued)
The LMS8117Aregulators have internal thermal shutdown to
protect the device from over-heating. Under all possible
operating conditions, the junction temperature of the
LMS8117A must be within the range of 0C to 125C. A
heatsink may be required depending on the maximum power
dissipation and maximum ambient temperature of the appli-
cation. To determine if a heatsink is needed, the power
dissipated by the regulator, P
D
, must be calculated:
I
IN
= I
L
+ I
G
P
D
= (V
IN
-V
OUT
)I
L
+ V
IN
I
G
Figure 6
shows the voltages and currents which are present
in the circuit.
The next parameter which must be calculated is the maxi-
mum allowable temperature rise, T
R
(max):
T
R
(max)=T
J
(max)-T
A
(max)
where T
J
(max) is the maximum allowable junction tempera-
ture (125C), and T
A
(max) is the maximum ambient tem-
perature which will be encountered in the application.
Using the calculated values for T
R
(max) and P
D
, the maxi-
mum allowable value for the junction-to-ambient thermal
resistance (
θ
JA
) can be calculated:
θ
JA
= T
R
(max)/P
D
If the maximum allowable value for
θ
is found to be
≥
136C/W for SOT-223 package or
≥
92C/W for TO-252
package, no heatsink is needed since the package alone will
dissipate enough heat to satisfy these requirements. If the
calculated value for
θ
JA
falls below these limits, a heatsink is
required.
As a design aid,
Table 1
shows the value of the
θ
of
SOT-223 and TO-252 for different heatsink area. The copper
patterns that we used to measure these
θ
s are shown at
the end of theApplication Notes Section.
Figure 7
and
Figure
8
reflects the same test results as what are in the
Table 1
.
Figure 9
and
Figure 10
shows the maximum allowable power
dissipation vs. ambient temperature for the SOT-223 and
TO-252 device.
Figure 11
and
Figure 12
shows the maxi-
mum allowable power dissipation vs. copper area (in
2
) for
the SOT-223 and TO-252 devices. Please see AN–1028 for
power enhancement techniques to be used with SOT-223
and TO-252 packages.
10119637
temperature is measured at the point where the leads contact with the mounting pad surface
10119616
FIGURE 6. Power Dissipation Diagram
L
www.national.com
9
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| LMS8117AMPX-ADJ/NOPB | 功能描述:IC REG LDO ADJ 1A SOT223-4 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:3.1V 輸入電壓:最高 5.5V 電壓 - 壓降（標(biāo)準(zhǔn)）:- 穩(wěn)壓器數(shù)量:1 電流 - 輸出:300mA 電流 - 限制（最?。?420mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-5 細(xì)型，TSOT-23-5 供應(yīng)商設(shè)備封裝:TSOT-23-5 包裝:帶卷 (TR) |
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