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參數資料
| 型號： | MAX8869EUE25 |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | 1A, MicroCap, Low-Dropout, Linear Regulator |
| 中文描述： | FIXED/ADJUSTABLE POSITIVE LDO REGULATOR, 0.35 V DROPOUT, PDSO16 |
| 封裝： | 4.40 MM, 1.10 MM HEIGHT, 0.65 MM PITCH, MO-153AC, TSSOP-16 |
| 文件頁數： | 8/10頁 |
| 文件大?。?/td> | 538K |
| 代理商： | MAX8869EUE25 |
M
below its nominal output voltage.
RST
remains low for
3ms after OUT has returned to its nominal value. A
100k
pullup resistor from
RST
to a suitable logic sup-
ply voltage (typically OUT) provides a logic control sig-
nal.
RST
can be used as a power-on-reset signal to a
microcontroller (μC) or can drive an external LED for
indicating a power failure.
RST
is low during shutdown.
RST
remains valid for an input voltage as low as 1V.
Soft-Start
As shown in Figure 4, a capacitor on SS allows a grad-
ual buildup of the MAX8869 output, reducing the initial
in-rush current peaks at startup. When
SHDN
is driven
low, the soft-start capacitor is discharged. When
SHDN
is driven high or power is applied to the device, a con-
stant 6μA current charges the soft-start capacitor. The
resulting linear ramp voltage on SS increases the cur-
rent-limit comparator threshold, limiting the P-channel
gate drive (see
Soft-Start Capacitor Selection
). Leave
SS floating to disable the soft-start feature.
Current Limiting
The MAX8869 features a 4A current limit when the out-
put voltage is in regulation. When the output voltage
drops by 8% below its nominal, the current limit folds
back to 1.7A. The output can be shorted to ground for
an indefinite period of time without damaging the
device. Avoid continuous output current of more than
1A to prevent damage.
Both the in-regulation and short-circuit current limits can
be reduced from their nominal values by reducing the
voltage at the soft-start pin (SS) below 1.25V. The cur-
rent limits scale proportionately with the voltage by I
LIM
= I
LIM_NOM
(V
SS
/ 1.25). Since the SS pin sources a
nominal 6μA current, the current limit can be set by
tying a resistor (R
SS
) between SS and GND, so that I
LIM
= I
LIM_NOM
(I
SS
R
SS
/ 1.25) where I
SS
= 6μA . With
R
SS
in place, soft-start can still be achieved by placing
a capacitor (C
SS
) in parallel with R
SS
. The output current
now ramps up asymptotically to the reduced current
limit rather than the nominal one, increasing the soft-
start time. The time required for the current limit to reach
90% of its steady-state value is given by t
SS
= 2.3
R
SS
C
SS
.
Thermal Overload Protection
Thermal overload protection limits total power dissipa-
tion in the MAX8869. When the junction temperature
exceeds T
J
= +170
°
C, the thermal sensor turns off the
pass transistor, allowing the IC to cool. The thermal sen-
sor turns the pass transistor on once the IC
’
s junction
temperature drops approximately 20
°
C. Continuous
short-circuit conditions will consequently result in a
pulsed output.
Thermal overload protection is designed to safeguard
the MAX8869 in the event of fault conditions. For con-
tinuous operation, do not exceed the absolute maxi-
mum junction temperature rating of T
J
= +150
°
C.
Operating Region and Power Dissipation
Maximum power dissipation of the MAX8869 depends
on the thermal resistance of the case and circuit board,
the temperature difference between the die junction
and ambient air, and the rate of air flow. The power dis-
sipation across the device is P = I
OUT
(V
IN
- V
OUT
). The
resulting maximum power dissipation is:
P
MAX
= [(T
J(MAX)
- T
A
) / (
θ
JC
+
θ
CA
)]
where (T
J(MAX)
- T
A
) is the temperature difference
between the maximum allowed die junction (150
°
C)
and the surrounding air;
θ
JC
(junction to case) is the
1A, MicroCap, Low-Dropout,
Linear Regulator
8
_______________________________________________________________________________________
Figure 3. Typical Operating Circuit with Adjustable Output
Voltage
IN
IN
IN
IN
SHDN
SS
GND
OUT
OUT
OUT
OUT
RST
SET
ON
OFF
C
OUT
1
μ
F
C
IN
1
μ
F
OUT
IN
RESET
OUTPUT
MAX8869
R1
R2
Figure 4. Typical Operating Circuit with Soft-Start and Current-
Limit Reduction
IN
IN
IN
IN
SHDN
SS
OUT
OUT
OUT
OUT
RST
SET
GND
ON
OFF
C
OUT
1
μ
F
C
IN
1
μ
F
OUT
IN
RESET
OUTPUT
MAX8869
C
SS
R
SS
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相關代理商/技術參數 |
參數描述 |
|---|---|
| MAX8869EUE25+ | 功能描述:低壓差穩(wěn)壓器 - LDO 1A MicroCap Linear Regulator 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 |
| MAX8869EUE25+T | 功能描述:低壓差穩(wěn)壓器 - LDO 1A MicroCap Linear Regulator 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 |
| MAX8869EUE25-T | 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 |
| MAX8869EUE33 | 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 |
| MAX8869EUE33+ | 功能描述:低壓差穩(wěn)壓器 - LDO 1A MicroCap Linear Regulator 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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