參數(shù)資料
型號(hào): SPX2940
元件分類: 基準(zhǔn)電壓源/電流源
英文描述: 1A Low Dropout Voltage Regulators(1A,低壓差穩(wěn)壓器)
中文描述: 1A低壓差穩(wěn)壓器(1A中,低壓差穩(wěn)壓器)
文件頁數(shù): 8/9頁
文件大?。?/td> 165K
代理商: SPX2940
Rev. 10/24/00
SPX2940
APPLICATION HINTS
External Capacitors
A minimum capacitance of 22
μ
F and conditions on ESR (Equivalent Series Resistance) must be met. The minimum value for the capacitance is
22
μ
F and can be increased without limit. However the ESR may cause loop instability if it is too high or too low. The following graph shows the
acceptable range for the ESR.
If the capacitor does not meet these requirements oscillation can result.
ESR is specified only at room temperature. Therefore the designer must ensure the proper behavior of the ESR over the temperature range. ESR, for
electrolytic capacitor, will increase by about 30X as the temperature is reduced from 25
°
C to -40
°
C. Aluminum electrolytic capacitors are not well
suited for low temperature operation.
Solid tantalum capacitors’ ESR are more stable over temperature, but expensive. A cost-effective approach is then to put in parallel a solid tantalum
and a aluminum electrolytic capacitors in the ratio25/75%.
Thermal Consideration
Although the SPX2940 offers some limiting circuitry for overload conditions, it is necessary not to exceed the maximum junction temperature, and
therefore to be careful about thermal resistance. The heat flow will follow the lowest resistance path, which is the Junction-to-case thermal
resistance. In order to insure the best
thermal flow of the component, a proper mounting is required. Note that the case of the device is electrically connected to the output. In case the
case has to be electrically isolated, a thermally conductive spacer can be used. However do not forget to consider its contribution to thermal
resistance.
Formulas for calculating the power dissipated in the regulator are the following:
I
IN
= I
L
+ I
G
P
D
= (V
IN
+ V
OUT
) * I
L
+ V
IN
* I
G
Where I
IN
is the input current, I
L
is the load current, I
G
is the ground current, P
D
is the power dissipated, V
IN
is the input voltage and V
OUT
is the
output voltage.
Output Capacitor ESR
OUTPUT CURRENT (mA)
E
)
1000
800
600
400
0
200
0.01
0.1
1
10
100
C
OUT
= 22
μ
F
V
O
= 5V
STABLE
REGION
相關(guān)PDF資料
PDF描述
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SPX2946 500mA Low Drop Out Voltage Regulator with Shutdown(Output Programmable From 1.24V to 29V)(500mA,低壓差穩(wěn)壓器(帶關(guān)斷,可編程輸出從1.24V-29V))
SPX2947 500mA Low Drop Out Voltage Regulator with Shutdown(Output Programmable From 1.24V to 29V)(500mA,低壓差穩(wěn)壓器(帶關(guān)斷,可編程輸出從1.24V-29V))
SPX2946T3-3.3 500mA Low Drop Out Voltage Regulator with Shutdown
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