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參數(shù)資料
| 型號(hào)： | NCV8664_07 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Ultra−Low Iq Low Dropout Linear Regulator |
| 文件頁(yè)數(shù)： | 9/13頁(yè) |
| 文件大小： | 158K |
| 代理商： | NCV8664_07 |
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NCV8664
http://onsemi.com
9
Circuit Description
The NCV8664 is a precision trimmed 3.3 V and 5.0 V
fixed output regulator. Careful management of light load
consumption combined with a low leakage process results
in a typical quiescent current of 22 A. The device has
current capability of 150 mA, with 600 mV of dropout
voltage at full rated load current. The regulation is provided
by a PNP pass transistor controlled by an error amplifier
with a bandgap reference. The regulator is protected by
both current limit and short circuit protection. Thermal
shutdown occurs above 150
°
C to protect the IC during
overloads and extreme ambient temperatures.
Regulator
The error amplifier compares the reference voltage to a
sample of the output voltage (V
out
) and drives the base of
a PNP series pass transistor by a buffer. The reference is a
bandgap design to give it a temperature
stable output.
Saturation control of the PNP is a function of the load
current and input voltage. Over saturation of the output
power device is prevented, and quiescent current in the
ground pin is minimized.
Regulator Stability Considerations
The input capacitor C
IN
in Figure 2 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 in series
with C
IN
. The output or compensation capacitor, C
OUT
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.
Tantalum, aluminum electrolytic, film, or ceramic
capacitors are all acceptable solutions, however, attention
must be paid to ESR constraints. 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
OUT
shown in Figure 2 should work for most
applications; however, it is not necessarily the optimized
solution. Stability is guaranteed at values C
OUT
≥
10 F for
5.0 V version, and C
OUT
≥
22 F for 3.3 V version and an
ESR
≤
9
within the operating temperature range. Actual
limits are shown in a graph in the Typical Performance
Characteristics section.
Calculating Power Dissipation in a Single Output
Linear Regulator
The maximum power dissipation for a single output
regulator (Figure 3) is:
PD(max)
[VIN(max)
IQ(max)
VI(max)
Iq
(eq. 1)
VOUT(min)]
Where:
V
IN(max)
is the maximum input voltage,
V
OUT(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:
150
o
C
PJA
TA
PD
(eq. 2)
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 heat sink will be
required. The current flow and voltages are shown in the
Measurement Circuit Diagram.
Heat Sinks
A heat sink 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. 3)
Where:
R
JC
= the junction
to
case thermal resistance,
R
CS
= the case
to
heat sink thermal resistance, and
R
SA
= the heat sink
to
ambient thermal resistance.
R
JA
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, heat sink and the
interface between them. These values appear in data sheets
of heat sink manufacturers. Thermal, mounting, and heat
sinking are discussed in the ON Semiconductor application
note AN1040/D, available on the ON Semiconductor
Website.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCV8664D50G | 功能描述:低壓差穩(wěn)壓器 - LDO NCV8664 SOIC8 FUSED 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 |
| NCV8664D50R2G | 功能描述:低壓差穩(wěn)壓器 - LDO NCV8664 SOIC8 FUSED 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 |
| NCV8664DT33RKG | 功能描述:低壓差穩(wěn)壓器 - LDO ULTRA LOW IQ 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 |
| NCV8664DT50RKG | 功能描述:低壓差穩(wěn)壓器 - LDO ULTRA LOW IQ 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 |
| NCV8664DT50RKG/H | 制造商:ON Semiconductor 功能描述: |
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