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參數(shù)資料
| 型號： | LP2957A |
| 廠商： | National Semiconductor Corporation |
| 文件頁數(shù)： | 3/14頁 |
| 文件大?。?/td> | 378K |
| 代理商： | LP2957A |
Electrical Characteristics
(Continued)
Limits in standard typeface are for T
J
= 25C, and limits in
boldface type
apply over the full operating temperature range. Un-
less otherwise specified: V
IN
= 6V, I
L
= 1 mA, C
L
= 2.2 μF, V
SD
= 3V.
Symbol
Parameter
Conditions
Typical
LP2957AI
Min
LP2957I
Min
Units
Max
Max
e
n
Output Noise Voltage
(10 Hz to 100 kHz)
I
L
= 100 mA
C
L
= 2.2 μF
C
L
= 33 μF
500
320
μV
RMS
SHUTDOWN INPUT
V
SD
(ON)
Output Turn-On
Threshold Voltage
Hysteresis
Input Bias
Current
1.155
1.140
1.305
1.320
1.155
1.140
1.305
1.320
V
HYST
I
B
6
10
mV
nA
V
IN(SD)
= 0V to 5V
30
50
30
50
30
50
30
50
DROPOUT DETECTION COMPARATOR
I
OH
Output “HIGH”
Leakage
V
OL
Output “LOW”
Voltage
V
THR
Upper Threshold
(Max)
Voltage
V
THR
Lower Threshold
(Min)
Voltage
HYST
Hysteresis
Note 1:
Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the de-
vice outside of its rated operating conditions.
Note 2:
The maximum allowable power dissipation is a function of the maximum junction temperature, T
(MAX), the junction-to-ambient thermal resistance,
θ
JA
,
and the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient temperature is calculated using:
V
OH
= 30V
0.01
1
2
1
2
μA
V
IN
= 4V
I
O
(COMP) = 400 μA
(Note 8)
150
250
400
150
100
230
160
250
400
150
100
230
160
mV
240
320
380
450
640
320
380
450
640
mV
(Note 8)
350
mV
(Note 8)
60
mV
Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The junction-to-ambient
thermal resistance of the TO-220 (without heatsink) is 60C/W and 73C/W for the TO-263. If the TO-263 package is used, the thermal resistance can be reduced
by increasing the P.C. board copper area thermally connected to the package: Using 0.5 Square inches of copper area,
θ
is 50C/W, with 1 square inch of copper
area,
θ
is 37C/W; and with 1.6 or more square inches of copper area,
θ
is 32C/W. The junction-to-case thermal resistance is 3C/W. If an external heatsink is
used, the effective junction-to-ambient thermal resistance is the sum of the junction-to-case resistance (3C/W), the specified thermal resistance of the heatsink se-
lected, and the thermal resistance of the interface between the heatsink and the LP2957 (see Application Hints).
Note 3:
Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 4:
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested separately for load regulation in the load ranges
0.1 mA–1 mA and 1 mA–250 mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 5:
Dropout voltage is defined as the input to output voltage differential at which the output voltage drops 100 mV below the value measured with a 1V input
to output differential.
Note 6:
Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground pin current.
Note 7:
Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation ef-
fects. Specifications are for a 200 mA load pulse at V
IN
= 20V (3W pulse) for T = 10 ms.
Note 8:
Voltages are referenced to the nominal regulated output voltage.
Note 9:
When used in dual-supply systems where the regulator load is returned to a negative supply, the output voltage must be diode-clamped to ground.
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| LP2957A-12 WAF | 制造商:Texas Instruments 功能描述: |
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| LP2957AIS/NOPB | 制造商:Texas Instruments 功能描述:Voltage Regulator IC |
| LP2957AISX | 功能描述:低壓差穩(wěn)壓器 - 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(shù)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 |
| LP2957AISX/NOPB | 功能描述:低壓差穩(wěn)壓器 - 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(shù)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 |
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