参数资料
型号: LM4140BCMX-2.0/NOPB
厂商: NATIONAL SEMICONDUCTOR CORP
元件分类: 基准电压源/电流源
英文描述: 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 2.048 V, PDSO8
封装: SOIC-8
文件页数: 15/15页
文件大小: 881K
代理商: LM4140BCMX-2.0/NOPB
Application Hints
INPUT CAPACITORS
Although not always required, an input capacitor is recom-
mended. A supply bypass capacitor on the input assures that
the reference is working from a source with low impedance,
which improves stability. A bypass capacitor can also im-
prove transient response by providing a reservoir of stored
energy that the reference can utilize in case where the load
current demand suddenly increases. The value used for C
IN
may be used without limit. Refer to the typical application
section for examples of input capacitors.
OUTPUT CAPACITORS
The LM4140 requires a 1F (nominally) output capacitor for
loop stability (compensation) as well as transient response.
During the sudden changes in load current demand, the
output capacitor must source or sink current during the time
it takes the control loop of the LM4140 to respond.
This capacitor must be selected to meet the requirements of
minimum capacitance and equivalent series resistance
(ESR) range.
In general, the capacitor value must be at least 0.2F (over
the actual ambient operating temperature), and the ESR
must be within the range indicated in Figure 1, Figure 2 and
TANTALUM CAPACITORS
Surface-mountable solid tantalum capacitors offer a good
combination of small physical size for the capacitance value,
and ESR in the range needed for by the LM4140. The results
of testing the LM4140 stability with surface mount solid
tantalum capacitors show good stability with values in the
range of 0.1F. However, optimum performance is achieved
with a 1F capacitor.
Tantalum capacitors that have been verified as suitable for
use with the LM4140 are shown in Table 1.
TABLE 1. Surface-Mount Tantalum Capacitor Selection
Guide
1F Surface-Mount Tantalums
Manufacturer
Part Number
Kemet
T491A105M010AS
NEC
NRU105N10
Siemens
B45196-E3105-K
Nichicon
F931C105MA
Sprague
293D105X0016A2T
2.2F Surface-Mount Tantalums
Kemet
T491A225M010AS
NEC
NRU225M06
Siemens
B45196/2.2/10/10
Nichicon
F930J225MA
Sprague
293D225X0010A2T
ALUMINUM ELECTROLYTIC CAPACITORS
Although probably not a good choice for a production design,
because of relatively large physical size, an aluminium elec-
trolytic capacitor can be used in the design prototype for an
LM4140 reference. A 1F capacitor meeting the ESR condi-
tions can be used. If the operating temperature drops below
0C, the reference may not remain stable, as the ESR of the
aluminium electrolytic capacitor will increase, and may ex-
ceed the limits indicated in the figures.
10107928
FIGURE 1. 0.22 F ESR Range
10107929
FIGURE 2. 1 F ESR Range
10107930
FIGURE 3. 10 F ESR Range
LM4140
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相关PDF资料
PDF描述
LM4140ACMX-1.0/NOPB 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 1.024 V, PDSO8
LM431ACML 1-OUTPUT TWO TERM VOLTAGE REFERENCE, 2.5 V, PSSO3
LM431CCMF 1-OUTPUT TWO TERM VOLTAGE REFERENCE, 2.495 V, PDSO3
LM431BCML 1-OUTPUT TWO TERM VOLTAGE REFERENCE, 2.495 V, PSSO3
LM431ACZSPCT 1-OUTPUT TWO TERM VOLTAGE REFERENCE, PBCY3
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