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參數(shù)資料
| 型號： | TPS73728 |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | 1A Low-Dropout Regulator with Reverse Current Protection |
| 中文描述： | 1A低壓差穩(wěn)壓器的反向電流保護 |
| 文件頁數(shù)： | 11/18頁 |
| 文件大?。?/td> | 578K |
| 代理商： | TPS73728 |
www.ti.com
BOARD LAYOUT RECOMMENDATION TO
IMPROVE PSRR AND NOISE
PERFORMANCE
To improve ac performance such as PSRR, output
noise, and transient response, it is recommended
that the printed circuit board (PCB) be designed with
separate ground planes for V
IN
and V
OUT
, with each
ground plane connected only at the GND pin of the
device. In addition, the ground connection for the
bypass capacitor should connect directly to the GND
pin of the device.
TRANSIENT RESPONSE
The low open-loop output impedance provided by the
NMOS
pass
element
configuration allows operation without a 1.0μF output
capacitor. As with any regulator, the addition of
additional capacitance from the output pin to ground
reduces
undershoot
magnitude
duration. In the adjustable version, the addition of a
capacitor, C
FB
, from the output to the adjust pin will
also improve the transient response.
INTERNAL CURRENT LIMIT
The TPS737xx internal current limit helps protect the
regulator during fault conditions. Foldback helps to
protect the regulator from damage during output
short-circuit conditions by reducing current limit when
V
OUT
drops below 0.5V.
SHUTDOWN
The Enable pin is active high and is compatible with
standard TTL-CMOS levels. V
below 0.5V (max)
turns the regulator off and drops the ground pin
current to approximately 10nA. When shutdown
capability is not required, the Enable pin can be
connected to V
IN
. When a pull-up resistor is used,
and operation down to 1.8V is required, use pull-up
resistor values below 50k
.
dV
dT
V
OUT
80k
C
OUT
R
LOAD
(3)
DROPOUT VOLTAGE
The TPS737xx uses an NMOS pass transistor to
achieve extremely low dropout. When (V
– V
) is
less than the dropout voltage (V
DO
), the NMOS pass
device is in its linear region of operation and the
input-to-output resistance is the R
DS, ON
of the NMOS
pass element.
dV
dT
V
OUT
(R
1
C
OUT
80k
R
2
) R
LOAD
(4)
REVERSE CURRENT
The NMOS pass element of the TPS737xx provides
inherent protection against current flow from the
output of the regulator to the input when the gate of
the pass device is pulled low. To ensure that all
charge is removed from the gate of the pass
element, the enable pin must be driven low before
the input voltage is removed. If this is not done, the
pass element may be left on because of stored
charge on the gate.
TPS737xx
SBVS067C–JANUARY 2006–REVISED AUGUST 2006
in
a
voltage
follower
but
increases
The TPS737xx does not have active pull-down when
the output is over-voltage. This architecture allows
applications that connect higher voltage sources,
such as alternate power supplies, to the output. This
architecture also results in an output overshoot of
several percent if the load current quickly drops to
zero when a capacitor is connected to the output.
The duration of overshoot can be reduced by adding
a load resistor. The overshoot decays at a rate
determined
by
output
capacitor
internal/external load resistance. The rate of decay is
given by:
C
and
the
(Fixed voltage version)
(Adjustable voltage version)
For
TPS737xx requires a larger voltage drop from V
to
V
OUT
to avoid degraded transient response. The
boundary
of
this
transient
approximately twice the dc dropout. Values of V
–
V
OUT
above
this
line
ensure
response.
large
step
changes
in
load
current,
the
dropout
region
is
normal
transient
After the enable pin is driven low, no bias voltage is
needed on any pin for reverse current blocking. Note
that reverse current is specified as the current
flowing out of the IN pin because of voltage applied
on the OUT pin. There will be additional current
flowing into the OUT pin as a result of the 80k
internal resistor divider to ground (see
Figure 1
and
Figure 2
).
Operating in the transient dropout region can cause
an increase in recovery time. The time required to
recover from a load transient is a function of the
magnitude of the change in load current rate, the
rate of change in load current, and the available
headroom
(V
IN
to
V
OUT
worst-case conditions [full-scale instantaneous load
change with (V
IN
– V
OUT
) close to dc dropout levels],
the TPS737xx can take a couple of hundred
microseconds to return to the specified regulation
accuracy.
voltage
drop).
Under
For the TPS73701, reverse current may flow when
V
FB
is more than 1.0V above V
IN
.
11
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| TPS73730DRBR | 功能描述:低壓差穩(wěn)壓器 - LDO Sgl Out LDO,1A,Fixed Rev Crnt Prot 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| TPS73730DRBT | 功能描述:低壓差穩(wěn)壓器 - LDO Sgl Out LDO,1A,Fixed Rev Crnt Prot 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| TPS73733DCQ | 功能描述:低壓差穩(wěn)壓器 - LDO Cap-Free 1A LDO Reg 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| TPS73733DCQ | 制造商:Texas Instruments 功能描述:Voltage Regulator |
| TPS73733DCQG4 | 功能描述:低壓差穩(wěn)壓器 - LDO Sgl Output LDO 1A Fixed 3.3V 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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