參數(shù)資料
型號(hào)： TPS79901DDC
廠商： Texas Instruments, Inc.
英文描述： 200mA, Low Quiescent Current, Ultra-Low Noise, High PSRR Low Dropout Linear Regulator
中文描述： 200mA的，低靜態(tài)電流，超低噪聲，高PSRR低壓降線性穩(wěn)壓器
文件頁(yè)數(shù)： 10/21頁(yè)
文件大?。?/td> 453K
代理商： TPS79901DDC
www.ti.com
APPLICATION INFORMATION
Feedback Capacitor Requirements
(TPS79901 only)
The feedback capacitor, C
FB
, shown in
Figure 29
is
required for stability. For a parallel combination of R
1
and R
equal to 250k
, any value from 3pF to 1nF
can be used. Fixed voltage versions have an internal
30pF feedback capacitor which is quick-charged at
start-up. The adjustable version does not have this
quick-charge circuit, so values below 5pF should be
used to ensure fast startup; values above 47pF can
be used to implement an output voltage soft-start.
Larger value capacitors also improve noise slightly.
The TPS79901 is stable in unity-gain configuration
(OUT tied to FB) without C
FB
.
Output Noise
In most LDOs, the bandgap is the dominant noise
source. If a noise reduction capacitor (C
) is used
with the TPS799xx, the bandgap does not contribute
significantly to noise. Instead, noise is dominated by
the output resistor divider and the error amplifier
input. To minimize noise in a given application, use a
0.01
μ
F noise reduction capacitor; for the adjustable
version, smaller value resistors in the output resistor
divider reduce noise. A parallel combination that
gives 2
μ
A of divider current will have the same noise
performance as a fixed voltage version. To further
optimize noise, equivalent series resistance of the
output capacitor can be set to approximately 0.2
.
This configuration maximizes phase margin in the
control loop, reducing total output noise by up to
10%.
Input and Output Capacitor Requirements
Although an input capacitor is not required for
stability, it is good analog design practice to connect
a 0.1
μ
F to 1
μ
F low ESR capacitor across the input
supply near the regulator. This will counteract
reactive
input
sources
response, noise rejection, and ripple rejection. A
higher-value capacitor may be necessary if large,
fast rise-time load transients are anticipated or the
device is located several inches from the power
source. If source impedance is not sufficiently low, a
0.1
μ
F input capacitor may be necessary to ensure
stability.
TPS799xx
GND
EN
NR
IN
OUT
V
IN
V
OUT
Optional input capacitor.
May improve source
impedance, noise, or PSRR.
Optional bypass capacitor
to reduce output noise
and increase PSRR.
2.2
μ
F
Ceramic
V
EN
TPS799xx
GND
EN
FB
IN
OUT
V
IN
V
OUT
R
1
C
FB
R
2
Optional input capacitor.
May improve source
impedance, noise, or PSRR.
V
OUT
=
×
1.193
(R
1
+ R
2
)
R
2
V
EN
2.2
μ
F
Ceramic
TPS799xx
SBVS056G–JANUARY 2005–REVISED AUGUST 2006
The TPS799xx family of LDO regulators combines
the high performance required of many RF and
precision analog applications with ultra-low current
consumption. High PSRR is provided by a high gain,
high bandwidth error loop with good supply rejection
at very low headroom (V
IN
– V
OUT
). Fixed voltage
versions provide a noise reduction pin to bypass
noise generated by the bandgap reference and to
improve PSRR while a quick-start circuit fast-charges
this capacitor at startup. The combination of high
performance and low ground current also make the
TPS799xx
an
excellent
applications.
All
versions
over-current protection and are fully specified from
–40
°
C to +125
°
C.
Figure 28
shows the basic circuit connections for
fixed
voltage
models.
connections
for
the
adjustable
(TPS79901). R
and R
can be calculated for any
output voltage using the formula in
Figure 29
.
Sample resistor values for common output voltages
are shown in
Figure 29
.
The TPS799xx is designed to be stable with
standard ceramic capacitors of values 2.2
μ
F or
larger. X5R and X7R type capacitors are best as
they have minimal variation in value and ESR over
temperature. Maximum ESR should be < 1.0
.
choice
have
for
thermal
portable
and
Figure
29
output
gives
the
version
and
improve
transient
Figure 28. Typical Application Circuit for
Fixed Voltage Versions
Figure 29. Typical Application Circuit for
Adjustable Voltage Version
10
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TPS79901DDCR 功能描述:低壓差穩(wěn)壓器 - LDO 200mA High PSRR 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(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
TPS79901DDCRG4 功能描述:低壓差穩(wěn)壓器 - LDO 200mA High PSRR 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(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
TPS79901DDCT 功能描述:低壓差穩(wěn)壓器 - LDO 200mA High PSRR 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(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
TPS79901DDCTG4 功能描述:低壓差穩(wěn)壓器 - LDO 200mA High PSRR 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(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
TPS79901DRVR 功能描述:低壓差穩(wěn)壓器 - LDO 200mA High PSRR 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(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
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