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參數(shù)資料
| 型號： | NCV4269 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | 5.0 V Micropower 150 mA LDO Linear Regulator with DELAY, Adjustable RESET, and Sense Output(帶有延遲，可調(diào)復(fù)位和檢測輸出功能的5.0V，微功率150mA LDO線性穩(wěn)壓器) |
| 中文描述： | 5.0V的微一百五十毫安LDO線性穩(wěn)壓器的延遲，可調(diào)復(fù)位和檢測輸出（帶有延遲，可調(diào)復(fù)位和檢測輸出功能的5.0V，150mA的微功率LDO的線性穩(wěn)壓器） |
| 文件頁數(shù)： | 11/15頁 |
| 文件大?。?/td> | 140K |
| 代理商： | NCV4269 |
NCV4269
http://onsemi.com
11
SENSE INPUT (SI) / SENSE OUTPUT (SO) VOLTAGE
MONITOR
An onchip comparator is available to provide early
warning to the microprocessor of a possible reset signal. The
output is from an open collector driver with an internal
20 k pull up resistor to output Q. The reset signal typically
turns the microprocessor off instantaneously. This can cause
unpredictable results with the microprocessor. The signal
received from the SO pin will allow the microprocessor time
to complete its present task before shutting down. This
function is performed by a comparator referenced to the
band gap voltage. The actual trip point can be programmed
externally using a resistor divider to the input monitor SI
(Figure 21). The values for R
SI1
and R
SI2
are selected for a
typical threshold of 1.20 V on the SI Pin.
SIGNAL OUTPUT
Figure 22 shows the SO Monitor timing waveforms as a
result of the circuit depicted in Figure 21. As the output
voltage (V
Q
) falls, the monitor threshold (V
SILOW
), is
crossed. This causes the voltage on the SO output to go low
sending a warning signal to the microprocessor that a reset
signal may occur in a short period of time. T
WARNING
is the
time the microprocessor has to complete the function it is
currently working on and get ready for the reset
shutdown signal.
Figure 22. SO Warning Waveform Time Diagram
V
Q
SI
V
RO
V
SILOW
T
WARNING
SO
STABILITY CONSIDERATIONS
The input capacitor C
I
in Figure 21 is necessary for
compensating input line reactance. Possible oscillations
caused by input inductance and input capacitance can be
damped by using a resistor of approximately 1.0 in series
with C
I.
The output or compensation capacitor helps determine
three main characteristics of a linear regulator: startup delay,
load transient response and loop stability.
The capacitor value and type should be based on cost,
availability, size and temperature constraints. A tantalum or
aluminum electrolytic capacitor is best, since a film or
ceramic capacitor with almost zero ESR can cause
instability. The aluminum electrolytic capacitor is the least
expensive solution, but, if the circuit operates at low
temperatures (25
°
C to 40
°
C), both the value and ESR of
the capacitor will vary considerably. The capacitor
manufacturer’s data sheet usually provides this information.
The value for the output capacitor C
Q
shown in Figure 21
should work for most applications; however, it is not
necessarily the optimized solution. Stability is guaranteed at
values C
Q
= 10 F and an ESR = 10 within the operating
temperature range. Actual limits are shown in a graph in the
typical data section.
CALCULATING POWER DISSIPATION IN A SINGLE
OUTPUT LINEAR REGULATOR
The maximum power dissipation for a single output
regulator (Figure 21) is:
PD(max)
[VI(max)
VQ(min)]IQ(max)
VI(max)Iq (eq. 4)
where:
V
I(max)
is the maximum input voltage,
V
Q(min)
is the minimum output voltage,
I
Q(max)
is the maximum output current for the application,
and I
q
is the quiescent current the regulator consumes at
I
Q(max)
.
Once the value of P
D(max)
is known, the maximum
permissible value of R
JA
can be calculated:
R
JA
= (150
°
C – T
A
) / P
D
The value of R
JA
can then be compared with those in the
package section of the data sheet. Those packages with
R
JA
’s less than the calculated value in equation 2 will keep
the die temperature below 150
°
C. In some cases, none of the
packages will be sufficient to dissipate the heat generated by
the IC, and an external heatsink will be required. The current
flow
and
voltages
Measurement Circuit Diagram.
(eq. 5)
are
shown
in
the
H
EATSINKS
A heatsink effectively increases the surface area of the
package to improve the flow of heat away from the IC and
into the surrounding air.
Each material in the heat flow path between the IC and the
outside environment will have a thermal resistance. Like
series electrical resistances, these resistances are summed to
determine the value of R
JA
:
RJA
RJC
RCS
RSA
(eq. 6)
where:
R
JC
= the junctiontocase thermal resistance,
R
CS
= the casetoheat sink thermal resistance, and
R
SA
= the heat sinktoambient thermal resistance.
R
JC
appears in the package section of the data sheet. Like
R
JA
, it too is a function of package type. R
CS
and R
SA
are
functions of the package type, heatsink and the interface
between them. These values appear in data sheets of
heatsink
manufacturers.
heatsinking
considerations
ON Semiconductor application note AN1040/D, available
on the ON Semiconductor website.
Thermal,
are
mounting,
discussed
and
the
in
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCV4269_07 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:5.0 V Micropower 150 mA LDO Linear Regulator with DELAY, Adjustable RESET, and Sense Output |
| NCV4269A | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:5.0 V Micropower 150 mA LDO Linear Regulator with DELAY, Adjustable RESET, and Sense Output |
| NCV4269AD133R2G | 制造商:ON Semiconductor 功能描述:3.3V 150MA LDO - Tape and Reel 制造商:ON Semiconductor 功能描述:IC REG LDO 3.3 150MA 制造商:ON Semiconductor 功能描述:REEL / 3.3V 150MA LDO |
| NCV4269AD150G | 功能描述:低壓差穩(wěn)壓器 - LDO 5.0V 150MA 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 |
| NCV4269AD150R2G | 功能描述:低壓差穩(wěn)壓器 - LDO 5.0V 150MA 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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