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參數(shù)資料
| 型號： | TK71245MTL |
| 廠商： | TOKO INC |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| 中文描述： | 4.5 V FIXED POSITIVE LDO REGULATOR, 0.2 V DROPOUT, PDSO5 |
| 封裝： | MINIATURE, SOT-23, SOT-25, 5 PIN |
| 文件頁數(shù)： | 15/18頁 |
| 文件大小： | 97K |
| 代理商： | TK71245MTL |
January 1999 TOKO, Inc.
Page 15
TK712xx
DEFINITION AND EXPLANATION OF TECHNICAL TERMS
LINE REGULATION (LINE REG)
Line regulation is the ability of the regulator to maintain a
constant output voltage as the input voltage changes.
LOAD REGULATION (LOAD REG)
Load regulation is the ability of the regulator to maintain a
constant output voltage as the load current changes. It is
a pulsed measurement to minimize temperature effects.
The load regulation is specified an output current step
condition of 1 mA to 60 mA.
QUIESCENT CURRENT (I
Q
)
The quiescent current is the current which flows through
the ground terminal under no load conditions (I
OUT
= 0 mA).
GROUND CURRENT (I
GND
)
Ground current is the current which flows through the
ground pin(s). It is defined as I
IN
- I
OUT
, excluding I
CONT
.
DROPOUT VOLTAGE (V
DROP
)
This is a measure of how well the regulator performs as the
input voltage decreases. The smaller the number, the
further the input voltage can decrease before regulation
problems occur. Nominal output voltage is first measured
when V
= V
+ 1 at a chosen load current. When the
output voltage has dropped 100 mV from the nominal, V
- V
is the dropout voltage. This voltage is affected by load
current and junction temperature.
OUTPUT NOISE VOLTAGE
This is the effective AC voltage that occurs on the output
voltage under the condition where the input noise is low
and with a given load, filter capacitor, and frequency
range.
THERMAL PROTECTION
This is an internal feature which turns the regulator off
when the junction temperature rises above 150
°
C. After
the regulator turns off, the temperature drops and the
regulator output turns back on. Under certain conditions,
the output waveform may appear to be an oscillation as the
output turns off and on and back again in succession.
PACKAGE POWER DISSIPATION (P
D
)
This is the power dissipation level at which the thermal
sensor is activated. The IC contains an internal thermal
sensor which monitors the junction temperature. When the
junction temperature exceeds the monitor threshold of
150
°
C, the IC is shut down. The junction temperature
rises as the difference between the input power (V
IN
x I
IN
)
and the output power (V
OUT
x I
OUT
) increases. The rate of
temperature rise is greatly affected by the mounting pad
configuration on the PCB, the board material, and the
ambient temperature. When the IC mounting has good
thermal conductivity, the junction temperature will be low
even if the power dissipation is great. When mounted on
the mounting pad, the power dissipation of the SOT-25 is
increased to 350 mW. For operation at ambient
temperatures over 25
°
C, the power dissipation of the
SOT-25 device should be derated at 2.8 mW/
°
C. To
determine the power dissipation for shutdown when
mounted, attach the device on the actual PCB and
deliberately increase the output current (or raise the input
voltage) until the thermal protection circuit is activated.
Calculate the power dissipation of the device by subtracting
the output power from the input power. These
measurements should allow for the ambient temperature
of the PCB. The value obtained from P
D
/(150
°
C - T
A
) is the
derating factor. The PCB mounting pad should provide
maximum thermal conductivity in order to maintain low
device temperatures. As a general rule, the lower the
temperature, the better the reliability of the device. The
thermal resistance when mounted is expressed as follows:
T
j
= 0
jA
x P
D
+ T
A
For Toko ICs, the internal limit for junction temperature is
150
°
C. If the ambient temperature (T
A
) is 25
°
C, then:
150
°
C = 0
jA
x P
D
+ 25
°
C
0
jA
= 125
°
C / P
D
P
D
is the value when the thermal sensor is activated. A
simple way to determine P
D
is to calculate V
IN
x I
IN
when
the output side is shorted. Input current gradually falls as
temperature rises. You should use the value when thermal
equilibrium is reached.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TK71250 | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| TK71250M | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| TK71250MTL | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| TK712XX | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| TK71340 | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TK71245MTL/J45 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
| TK71250 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
| TK71250M | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
| TK71250MTL | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
| TK71250MTL/J50 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
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