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參數(shù)資料
| 型號： | L6720 |
| 文件頁數(shù)： | 7/9頁 |
| 文件大?。?/td> | 157K |
| 代理商： | L6720 |
When V
OUT
= 0.7V Q2 and D3 turn on and also
Q1 whose saturation turns off the power PWR. In
this condition (BV
CBO
) it can withstand the maxi-
mum negativeovervoltage (-18V).
If we now have an overload on V
OUT
(after the di-
ode) for examplewith V
IN
= 12V, V
OUT
= 8V,
P
d
= 4W, the temperature of the chip increases
to the thermal shutdown intervention, so that
V
OUT
= 0. However Q1 and Q2 cannot turn on be-
cause we have 2 diodes (D1 and D2) against 3
diodes(D3, D
EXT
, Base-Emitterof Q2).
If the over load is on point V
O
(beforethe external
diode) as before the chip temperature increases
until shutdown.But inthat condition(with V
OUT
= 0)
we have now 2 diodes (D1, D2) against other 2
diodes (D3, Q2 Base-Emitter); than the power
switch doesn’t turn on because of a slight differ-
ence between the thermal coefficient of the 4 di-
odes.
We will have the new switching-on of power
switch only when the chip temperaturedecreases
of about 80
°
C (beingkept off by Q1 and Q2).
In conclusion with or without the external diode
the absolute value of the thermal shutdown is the
same, but the hysteresis is higher without the ex-
ternal diode.
THERMAL CHARACTERISTICS
The transient thermal resistance of the 16+2+2
powerdip package is shown in Fig. 2: a typical
R
th j-amb
of 50
°
C/W roughly can be seen.To be
able to well sink out the heast from the inside of
the package, the four control pins can be closely
connected to a p.c.b. copper side. By considering
the two square sides of Fig. 4, the thermal resis-
tance junction-ambient can be reduced according
to Fig. 3.
Figure 2:
DIP 16+2+2 Transient Thermal Resis-
tance for single pulses.
Figure 3:
Typical R
th
j-a of Powerdip 16+2+2 vs
side1 for heat sink on the PCBlower side.
Figure4:
Two ”O(jiān)n Board” squareheat sink
L6720 - L6721
7/9
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| L6721 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Peripheral Interface |
| L6722 | 功能描述:DC/DC 開關(guān)控制器 3 Phase Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| L6722TR | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 3 Phase Controller RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| L6725 | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Vltg Mode PWM Controller RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| L6725_07 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Voltage mode PWM controller with bootstrap anti-discharging system |
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