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参数资料
| 型号： | AS2940T-5.0 |
| 元件分类： | 固定正电压单路输出LDO稳压器 |
| 英文描述： | 5 V FIXED POSITIVE LDO REGULATOR, 0.2 V DROPOUT, PSSO2 |
| 封装： | TO-263, 3 PIN |
| 文件页数： | 8/8页 |
| 文件大小： | 121K |
| 代理商： | AS2940T-5.0 |
Rev. 10/11/00
AS2940
APPLICATION HINTS
External Capacitors
A minimum capacitance of 22
F and conditions on ESR (Equivalent Series Resistance) must be met. The minimum value for the capacitance is
22
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 AS2940 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:
IIN = IL + IG
PD = (VIN + VOUT) * IL + VIN * IG
Where IIN is the input current, IL is the load current, IG is the ground current, PD is the power dissipated, VIN is the input voltage and VOUT is the
output voltage.
Output Capacitor ESR
OUTPUT CURRENT (mA)
EQUIVALENT
SERIES
RESISTANCE
(
)
1000
800
600
400
0
200
0.01
0.1
1
10
100
C
OUT = 22 F
V
O = 5V
STABLE
REGION
相关PDF资料 |
PDF描述 |
|---|---|
| AS2940U-5.0 | 5 V FIXED POSITIVE LDO REGULATOR, 0.2 V DROPOUT, PSFM3 |
| AS3431AN | 1-OUTPUT TWO TERM VOLTAGE REFERENCE, 2.503 V, PBCY3 |
| AS37P010410 | ROCKER SWITCH, SPDT, MOMENTARY, THROUGH HOLE-STRAIGHT |
| AS39P000410 | ROCKER SWITCH, SPDT, LATCHED, 0.02A, 20VDC, THROUGH HOLE-STRAIGHT |
| AS39P020720 | ROCKER SWITCH, SPDT, LATCHED, THROUGH HOLE-STRAIGHT |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AS2940T-X | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:1A Low Dropout Voltage Regulators |
| AS2940U-5.0 | 制造商:Alpha & Omega Semiconductor 功能描述: |
| AS2940U-X | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:1A Low Dropout Voltage Regulators |
| AS2945B | 制造商:Alpha & Omega Semiconductor 功能描述: |
| AS2945BP-2.5 | 制造商:Alpha & Omega Semiconductor 功能描述: |
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