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參數資料
| 型號： | REG1117A-TR |
| 英文描述： | Positive Adjustable Voltage Regulator |
| 中文描述： | 積極可調電壓穩(wěn)壓器 |
| 文件頁數： | 7/12頁 |
| 文件大小： | 382K |
| 代理商： | REG1117A-TR |
REG1117, REG1117A
SBVS001B
7
www.ti.com
THERMAL CONSIDERATIONS
The REG1117 has current limit and thermal shutdown
circuits that protect it from overload. The thermal shutdown
activates at approximately T
J
= 165
°
C. For continuous op-
eration, however, the junction temperature should not be
allowed to exceed 125
°
C. Any tendency to activate the
thermal shutdown in normal use is an indication of an
inadequate heat sink or excessive power dissipation. The
power dissipation is equal to:
P
D
= (V
IN
– V
OUT
) I
OUT
The junction temperature can be calculated by:
T
J
= T
A
+ P
D
(
θ
JA
)
where T
A
is the ambient temperature, and
θ
JA
is the junction-to-ambient thermal resistance
A simple experiment will determine whether the maximum
recommended junction temperature is exceeded in an actual
circuit board and mounting configuration: Increase the am-
bient temperature above that expected in normal operation
until the device’s thermal shutdown is activated. If this
occurs at more than 40
°
C above the maximum expected
ambient temperature, then the T
J
will be less than 125
°
C
during normal operation.
The internal protection circuitry of the REG1117 was de-
signed to protect against overload conditions. It was not
intended to replace proper heat sinking. Continuously run-
ning the REG1117 into thermal shutdown will degrade
reliability.
LAYOUT CONSIDERATIONS
The DDPAK (REG1117F-3.3 and REG1117FA) is a sur-
face-mount power package that has excellent thermal char-
acteristics. For best thermal performance, its mounting tab
should be soldered directly to a circuit board copper area, as
shown in Figure 3. Increasing the copper area improves heat
dissipation. Figure 4 shows typical thermal resistance from
junction-to-ambient as a function of the copper area.
FIGURE 3. DDPAK Thermal Resistance versus Circuit Board Copper Area.
FIGURE 4. DDPAK Thermal Resistance versus Circuit Board Copper Area.
3-Lead DDPAK
(1)
NOTE: (1) For improved thermal performance increase
footprint area. See Figure 4,
“
Thermal Resistance vs
Circuit Board Copper Area
”
.
All measurements
in inches.
0
0
0
0.51
0.10
0.155
0.05
Circuit Board Copper Area
REG1117F
DDPAK Surface-Mount Package
THERMAL RESISTANCE vs
CIRCUIT BOARD COPPER AREA
60
50
40
30
20
10
T
J
°
C
0
1
2
3
4
5
Copper Area (inches
2
)
REG1117F
DDPAK Surface Mount Package
1oz copper
θ
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相關代理商/技術參數 |
參數描述 |
|---|---|
| REG1117F-3.3 | 制造商:Texas Instruments 功能描述:Voltage Regulator, +3.3V, Bi-Polar, 3 Pin, Plastic, SIP |
| REG1117F-3.3/2K5 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:VOLT REGULATOR|FIXED|+3.3V|BIPOLAR|SIP|3PIN|PLASTIC |
| REG1117F-3.3/500 | 功能描述:低壓差穩(wěn)壓器 - LDO 800mA & 1A 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(jié):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 |
| REG1117F-3.3/500G3 | 功能描述:低壓差穩(wěn)壓器 - LDO 800mA & 1A 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(jié):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 |
| REG1117F-3.3500 | 制造商:BB 制造商全稱:BB 功能描述:800mA and 1A Low Dropout Positive Regulator 1.8V, 2.5V, 2.85, 3.3V, 5V, and Adjustable |
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