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參數(shù)資料
| 型號： | MAX8890 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Integrated Cellular RF-Section Power-Management IC |
| 中文描述： | 集成的蜂窩電話RF部分電源管理IC |
| 文件頁數(shù)： | 9/12頁 |
| 文件大小： | 233K |
| 代理商： | MAX8890 |
M
Integrated Cellular RF-S ec tion
Power-Management IC
_______________________________________________________________________________________
9
When the junction temperature exceeds T
J
= 160
°
C, a
thermal sensor activates the shutdown logic, disabling
the overheated regulator. The thermal sensor turns the
linear regulator on again after the regulator
’
s junction
temperature cools by 15
°
C, resulting in a pulsed output
during continuous thermal-overload conditions. For
continuous operation, do not exceed the absolute maxi-
mum junction-temperature rating of T
J
= 150
°
C.
Applic ations Information
Capac itor S elec tion and Regulator
S tability
Capacitors are required at each input and each output
of the MAX8890 for stable operation over the full load
range and full temperature range. Connect a minimum
2.2μF ceramic capacitor between OUT_ and ground to
ensure stability and optimum transient response. Use
larger 10μF ceramic output capacitors for lower noise
requirements.
The input capacitor (C
IN
_) lowers the source imped-
ance of the input supply, thereby reducing the input
noise and improving transient response. Connect a
minimum 1μF ceramic capacitance between each IN_
and ground. Place all input and output capacitors as
close to the MAX8890 as possible to minimize the
impact of PC board trace impedance. Because IN1
and IN2 are next to each other, they may easily share a
single 2.2μF or larger ceramic capacitor.
Surface-mount ceramic capacitors have very low ESR
and are commonly available in values up to 10μF.
However, note that some ceramic dielectrics exhibit
large capacitance and ESR variation with temperature.
Z5U and Y5V dielectrics may require a minimum 3.3μF
nominal output capacitance, especially with low tem-
perature operation.
Referenc e Bypass Capac itor
An external bypass capacitor is connected to BP to
reduce the inherent reference noise. The capacitor
forms a lowpass filter in conjunction with an internal
network. Use a 0.01μF or greater ceramic capacitor
connected as close to BP as possible. Capacitance
values greater than 0.01μF will increase the startup
time. (See
Typical Operating Characteristics
for startup
waveforms.) For the lowest noise, increase the bypass
capacitor to 0.1μF. Values above 0.1μF provide no per-
formance improvement and are therefore not recom-
mended. Do not place any additional loading on this
reference bypass pin.
Noise, PS RR, and T ransient Response
The MAX8890 is designed to operate with low dropout
voltages and low quiescent currents in battery-powered
systems while providing low noise, fast transient
response, and high AC rejection. See the
Typical
Operating Characteristics
for a plot of Power-Supply
Rejection Ratio (PSRR) vs. Frequency. When operating
from noisy sources, improved supply-noise rejection
and transient response can be achieved by increasing
the values of the input and output bypass capacitors
and through passive filtering techniques.
The MAX8890 load-transient response graphs (see
Typical Operating Characteristics
) show two compo-
nents of the output response: a DC shift from the output
impedance due to the load current change and the
transient response. Increasing the output capacitor
’
s
value and decreasing the ESR reduces the transient
under/overshoot.
Input-Output (Dropout) V oltage
A regulator
’
s minimum input-to-output voltage differen-
tial (dropout voltage) determines the lowest useable
input supply voltage. Once the linear regulator reaches
dropout, the series pass transistor is fully on and regu-
lation ceases. The output voltage tracks the input volt-
age as the input voltage drops lower. Because the
MAX8890 uses P-channel MOSFET pass transistors, its
dropout voltage is a function of the MOSFET
’
s drain-to-
source on-resistance (R
DS(ON)
) multiplied by the load
current (see
Typical Operating Characteristics
):
V
DROPOUT
= V
IN
_ - V
OUT
_ = R
DS(ON)
I
OUT
_
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相關(guān)代理商/技術(shù)參數(shù) |
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| MAX8890EGCAAA | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8890EGCABK | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8890EGCAKM | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8890EGCBBB | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8890EGCBKK | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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