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參數(shù)資料
| 型號： | LP2983IM5-1.0 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Micropower 150 mA Voltage Regulator in SOT-23 Package For Output Voltages 1.2V Designed for Use with Very Low ESR Output Capacitors |
| 中文描述： | 1 V FIXED POSITIVE REGULATOR, PDSO5 |
| 封裝： | SOT-23, SOP-5 |
| 文件頁數(shù)： | 10/11頁 |
| 文件大?。?/td> | 285K |
| 代理商： | LP2983IM5-1.0 |
Application Hints
EXTERNAL CAPACITORS
Like any low-dropout regulator, the LP2983 requires external
capacitors for regulator stability. These capacitors must be
correctly selected for good performance.
Input Capacitor
An input capacitor whose capacitance is
≥
1 μF is required
between the LP2983 input and ground (the amount of ca-
pacitance may be increased without limit).
This capacitor must be located a distance of not more than 1
cm from the input pin and returned to a clean analog ground.
Any good quality ceramic, tantalum, or film capacitor may be
used at the input.
Important:
Tantalum capacitors can suffer catastrophic fail-
ure
due
to
surge
current
low-impedance source of power (like a battery or very large
capacitor). If a Tantalum capacitor is used at the input, it
must be guaranteed by the manufacturer to have a surge
current rating sufficient for the application.
There are no requirements for ESR on the input capacitor,
but tolerance and temperature coefficient must be consid-
ered when selecting the capacitor to ensure the capacitance
will be
≥
1 μF over the entire operating temperature range.
Output Capacitor
The LP2983 is designed specifically to work with ceramic
output capacitors, utilizing circuitry which allows the regula-
tor to be stable across the entire range of output current with
an output capacitor whose ESR is as low as zero ohms. See
Figure 1 below.
when
connected
to
a
The LP2983 requires a minimum of 2.2 μF on the output
(output capacitor size can be increased without limit).
It is important to remember that capacitor tolerance and
variation with temperature must be taken into consideration
when selecting an output capacitor so that the minimum
required amount of output capacitance is provided over the
full operating temperature range. It should be noted that
ceramic capacitors can exhibit large changes in capacitance
with temperature (see next section, Capacitor Characteris-
tics).
The output capacitor must be located not more than 1 cm
from the output pin and returned to a clean analog ground.
CAPACITOR CHARACTERISTICS
The LP2983 was designed to work with ceramic capacitors
on the output to take advantage of the benefits they offer: for
capacitance values in the 2.2 μF to 4.7 μF range, ceramics
are the least expensive and also have the lowest ESR
values
(which
makes
them
high-frequency noise).
One disadvantage of ceramic capacitors is that their capaci-
tance can vary with temperature. Most large value ceramic
capacitors (
≥
2.2 μF) are manufactured with the Z5U or Y5V
temperature characteristic, which results in the capacitance
dropping by more than 50% as the temperature goes from
25C to 85C.
This could cause problems if a 2.2 μF capacitor were used
on the output since it will drop down to approximately 1 μF at
high ambient temperatures (which could cause the LP2983
to oscillate). If Z5U or Y5V capacitors are used on the output,
a minimum capacitance value of 4.7 μF must be observed.
Abetter choice for temperature coefficient in ceramic capaci-
tors is X7R, which holds the capacitance within
±
15%. Un-
fortunately, the larger values of capacitance are not offered
by all manufacturers in the X7R dielectric.
best
for
eliminating
ON/OFF INPUT OPERATION
The LP2983 is shut off by driving the ON/OFF input low, and
turned on by pulling it high. If this feature is not to be used,
the ON/OFF input should be tied to V
IN
to keep the regulator
output on at all times.
To assure proper operation, the signal source used to drive
the ON/OFF input must be able to swing above and below
the specified turn-on/turn-off voltage thresholds listed in the
Electrical Characteristics section under V
. To prevent
mis-operation, the turn-on (and turn-off) voltage signals ap-
plied to the ON/OFF input must have a slew rate which is
≥
40 mV/μs.
Caution:
the regulator output voltage can not be guaranteed
if a slow-moving AC (or DC) signal is applied that is in the
range between the specified turn-on and turn-off voltages
listed under the electrical specification V
ON/OFF
(see Electri-
cal Characteristics).
REVERSE INPUT-OUTPUT VOLTAGE
The PNP power transistor used as the pass element in the
LP2983 has an inherent diode connected between the regu-
lator output and input. During normal operation (where the
input voltage is higher than the output) this diode is
reverse-biased.
However, if the output is pulled above the input, this diode
will turn ON and current will flow into the regulator output. In
such cases, a parasitic SCR can latch which will allow a high
current to flow into V
IN
(and out the ground pin), which can
damage the part.
In any application where the output may be pulled above the
input, an external Schottky diode must be connected from
V
to V
(cathode on V
, anode on V
), to limit the
reverse voltage across the LP2983 to 0.3V (see Absolute
Maximum Ratings).
C
= 2.2μF
Ceramic to ESR Pin
20029120
FIGURE 1.
L
www.national.com
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| LP2983IM5X-1.0 | 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(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 |
| LP2983IM5X-1.0/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(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 |
| LP2983IM5X-1.2 | 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(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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