參數(shù)資料
型號: LM238K
廠商: 意法半導體
英文描述: THREE-TERMINAL 5 A ADJUSTABLE VOLTAGE REGULATORS
中文描述: 三端可調(diào)5甲電壓調(diào)節(jié)器
文件頁數(shù): 7/12頁
文件大?。?/td> 186K
代理商: LM238K
will be 0.05
(1 + R
2
/R
1
) or inthis case, 11.5 times
worse.
Figure 2shows the effectof resistancebetween the
regulator and 140
set resistor.
WiththeTO-3package,itiseasy tominimize there-
sistance from the case to the set resistor, by using
2 separate leads to the case. The ground of R2can
be returned near the ground of the load to provide
remote ground sensing and improve load regula-
tion.
PROTECTION DIODES
WhenexternalcapacitorsareusedwithanyICregu-
lator it is sometimes necessary to add protection
diodes to prevent the capacitors from discharging
through low current points into the regulator. Most
Figure 2 :
Regulator with Line Resistance inOut-
put Lead.
20
μ
F capacitors have low enoughinternal seriesre-
sistance to deliver 20A spikes when shorted. Al-
thoughthe surge is short, there is enough energy to
damage parts of the IC.
When anoutput capacitor is connected toa regula-
tor and the input isshorted, the output capacitor will
discharge into the output of the regulator. The dis-
chargecurrent depends on the value of thecapaci-
tor, the output voltage of the regulator, and therate
of decrease of V
I
. In the LM338 this discharge path
is through a large junction that isable tosustain 25A
surgewithno problem.Thisis nottrue ofother types
of positive regulators. For output capacitors of
100
μ
F or less at output of 15V or less, there is no
need to use diodes.
The bypass capacitor on the adjustment terminal
can discharge through a low current junction. Dis-
charge occurs when either the input or output is
shorted. Internal to the LM338 is a 50
resistor
which limits the peak discharge current. Noprotec-
tionis neededfor outputvoltages of25V or less and
10
μ
F capacitance. Figure 3 shows an LM338 with
protection diodes included for use with outputs
greaterthan 25V and high values of output capacit-
ance.
Figure 3 :
Regulator with Protection Diodes.
LM138-LM238-LM338
7/12
相關PDF資料
PDF描述
LM238 Very Low Drop Voltage Regulator with Inhabit(帶禁止的低壓差電壓穩(wěn)壓器)
LM138 Very Low Drop Voltage Regulator with Inhabit(帶禁止的低壓差電壓穩(wěn)壓器)
LM338 Very Low Drop Voltage Regulator with Inhabit(帶禁止的低壓差電壓穩(wěn)壓器)
LM248 Quadruple Operational Amplifiers(四路運放)
LM348 Quadruple Operational Amplifiers(四通用運算放大器)
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