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參數(shù)資料
| 型號： | RT8008-25QB |
| 廠商： | Richtek Technology Corporation |
| 英文描述： | 1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter |
| 中文描述： | 1.5MHz的，600mA，高效率的PWM降壓型DC / DC轉(zhuǎn)換器 |
| 文件頁數(shù)： | 11/14頁 |
| 文件大小： | 223K |
| 代理商： | RT8008-25QB |
RT8008
11
DS8008-04 March 2007
www.richtek.com
curves. Thus, to obtain I
2
R losses, simply add R
SW
to R
L
and multiply the result by the square of the average output
current.
Other losses including C
IN
and C
OUT
ESR dissipative
losses and inductor core losses generally account for less
than 2% of the total loss.
Thermal Considerations
The maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
junction to ambient. The maximum power dissipation can
be calculated by following formula :
P
D(MAX)
= ( T
J(MAX)
- T
A
) /
θ
JA
Where T
J(MAX)
is the maximum operation junction
temperature 125
°
C, T
A
is the ambient temperature and the
θ
JA
is the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT8008 DC/DC converter, where T
J (MAX)
is the maximum
junction temperature of the die (125
°
C) and T
A
is the
maximum ambient temperature. The junction to ambient
thermal resistance
θ
JA
is layout dependent. For
SOT-23-5/TSOT-23-5 packages, the thermal resistance
θ
JA
is 250
°
C/W on the standard JEDEC 51-3 single-layer
thermal test board. The maximum power dissipation at
T
A
= 25
°
C can be calculated by following formula :
P
D(MAX)
= ( 125
°
C - 25
°
C ) / 250 = 0.4 W for SOT-23-5/
TSOT-23-5 packages
The maximum power dissipation depends on operating
ambient temperature for fixed T
J(MAX)
and thermal
resistance
θ
JA
. For RT8008 packages, the Figure 5 of
derating curves allows the designer to see the effect of
rising ambient temperature on the maximum power
allowed.
The value of junction to case thermal resistance
θ
JC
is
popular for users. This thermal parameter is convenient
for users to estimate the internal junction operated
temperature of packages while IC operating. It's
independent of PCB layout, the surroundings airflow effects
and temperature difference between junction to ambient.
The operated junction temperature can be calculated by
following formula :
T
J
= T
C
+ P
D
x
JC
Where T
C
is the package case (Pin 2 of package leads)
temperature measured by thermal sensor, P
D
is the power
dissipation defined by user's function and the
θ
JC
is the
junction to case thermal resistance provided by IC
manufacturer. Therefore it's easy to estimate the junction
temperature by any condition.
Checking Transient Response
The regulator loop response can be checked by looking
at the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, V
OUT
immediately shifts by an amount
equal to
I
LOAD
(ESR), where ESR is the effective series
resistance of C
OUT
.
I
LOAD
also begins to charge or
discharge C
OUT
generating a feedback error signal used
by the regulator to return V
OUT
to its steady-state value.
During this recovery time, V
OUT
can be monitored for
overshoot or ringing that would indicate a stability problem.
Layout Considerations
Follow the PCB layout guidelines for optimal performance
of RT8008.
}
For the main current paths as indicated in bold lines in
Figure 6, keep their traces short and wide.
}
Put the input capacitor as close as possible to the device
pins (VIN and GND).
}
LX node is with high frequency voltage swing and should
be kept small area. Keep analog components away from
LX node to prevent stray capacitive noise pick-up.
Figure 5. Derating Curves for RT8008 Package
0
50
100
150
200
250
300
350
400
450
0
20
40
60
80
100
120
140
Ambient Temperature (
°
C)
M
Single Layer PCB
SOT-23-5, TSOT-23-5 Packages
相關(guān)PDF資料 |
PDF描述 |
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| RT8008-25QJ5 | 1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter |
| RT8008-33PB | 1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter |
| RT8008-33PJ5 | 1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter |
| RT8008-33QB | 1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter |
| RT8008-33QJ5 | 1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| RT8008-25QJ5 | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter |
| RT8008-33CB | 制造商:RICHTEK 功能描述:1.5MHz, 600mA, PWM Step-Down DC/DC Converter |
| RT8008-33GB | 功能描述:IC REG BUCK SYNC 3.3V SOT23-5 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:5 V ~ 25 V 輸入電壓:2.3 V ~ 5.5 V PWM 型:電流模式 頻率 - 開關(guān):600kHz，1.2MHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP，8-MSOP（0.118"，3.00mm 寬） 包裝:管件 供應(yīng)商設(shè)備封裝:8-MSOP |
| RT8008-33GJ5 | 功能描述:IC REG BUCK SYNC 3.3V TSOT23-5 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:5 V ~ 25 V 輸入電壓:2.3 V ~ 5.5 V PWM 型:電流模式 頻率 - 開關(guān):600kHz，1.2MHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP，8-MSOP（0.118"，3.00mm 寬） 包裝:管件 供應(yīng)商設(shè)備封裝:8-MSOP |
| RT8008-33PB | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter |
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