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參數(shù)資料
| 型號(hào)： | TK73233 |
| 廠商： | TOKO Inc. |
| 元件分類： | 基準(zhǔn)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： | 無電容，NMOS管，150mA的低壓差穩(wěn)壓器的反向電流保護(hù) |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 117K |
| 代理商： | TK73233 |
Page 10
January 1999 TOKO, Inc.
TK732xx
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.
The range of usable currents can also be found from the
graph below.
Procedure:
1)
2)
Find P
D
P
is taken to be P
x (
Note: It is not necessary to connect
a ceramic capacitor in parallel with an aluminum or tantalum output
capacitor.
(~0.8 - 0.9)
SENSOR CIRCUITS
Overcurrent Sensor
The overcurrent sensor protects the device if the output is
shorted to ground.
Thermal Sensor
The thermal sensor protects the device if the junction
temperature exceeds the safe value (T
j
= 150
°
C). This
temperature rise can be caused by extreme heat, excessive
power dissipation caused by large output voltage drops, or
excessive output current. The regulator will shut off when
the temperature exceeds the safe value. As the junction
temperature decreases, the regulator will begin to operate
again. Under sustained fault conditions, the regulator
output will oscillate as the device turns off then resets.
Damage may occur to the device under extreme fault
conditions.
Reverse Voltage Protection
Reverse voltage protection prevents damage due to the
output voltage being higher than the input voltage. This
fault condition can occur when the output capacitor remains
charged and the input is reduced to zero, or when an
external voltage higher than the input voltage is applied to
the output side.
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 recommended mounting pad, the power dissipation of
the SOT-23L-8 is increased to 600 mW. For operation at
ambient temperatures over 25
°
C, the power dissipation of
the SOT-23L-8 device should be derated at 4.8 mW/
°
C. To
determine the power dissipation for shutdown when
mounted, attach the device on the actual PCB and
DEFINITION AND EXPLANATION OF TECHNICAL TERMS (CONT.)
PD
DPD
25
50
75
150
(mW)
TA (
°
C)
3
6
5
4
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TK73233M | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| TK73233MCLH | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| TK73234 | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| TK73234M | Cap-Free, NMOS, 150mA Low Dropout Regulator with Reverse Current Protection |
| TK73234MCLH | 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 |
|---|---|
| TK73233M | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
| TK73233MCLH | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
| TK73233MCLH/33 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
| TK73233MILH | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
| TK73233MILH/33 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:LOW DROPOUT REGULATOR |
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