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參數資料
| 型號： | LTC1628C |
| 廠商： | Linear Technology Corporation |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| 中文描述： | 抗輻射高效，5安培開關穩(wěn)壓器 |
| 文件頁數： | 11/32頁 |
| 文件大小： | 375K |
| 代理商： | LTC1628C |
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11
LTC1628-SYNC
Output Overvoltage Protection
An overvoltage comparator, OV, guards against transient
overshoots (>7.5%) as well as other more serious condi-
tions that may overvoltage the output. In this case, the top
MOSFET is turned off and the bottom MOSFET is turned on
until the overvoltage condition is cleared.
Power Good (PGOOD) Pin
The PGOOD pin is connected to an open drain of an internal
MOSFET. The MOSFET turns on and pulls the pin low when
either output is not within
±
7.5% of the nominal output
level as determined by the resistive feedback divider.
When both outputs meet the
±
7.5% requirement, the
MOSFET is turned off within 10
μ
s and the pin is allowed to
be pulled up by an external resistor to a source of up to 7V.
Foldback Current, Short-Circuit Detection
and Short-Circuit Latchoff
The RUN/SS capacitors are used initially to limit the inrush
current of each switching regulator. After the controller
has been started and been given adequate time to charge
up the output capacitors and provide full load current, the
RUN/SS capacitor is used in a short-circuit time-out
circuit. If the output voltage falls to less than 70% of its
nominal output voltage, the RUN/SS capacitor begins
discharging on the assumption that the output is in an
overcurrent and/or short-circuit condition. If the condi-
tion lasts for a long enough period as determined by the
size of the RUN/SS capacitor, the controller will be shut
down until the RUN/SS pin(s) voltage(s) are recycled.
This built-in latchoff can be overridden by providing a
>5
μ
A pull-up at a compliance of 5V to the RUN/SS pin(s).
This current shortens the soft start period but also pre-
vents net discharge of the RUN/SS capacitor(s) during an
overcurrent and/or short-circuit condition. Foldback cur-
rent limiting is also activated when the output voltage falls
below 70% of its nominal level whether or not the short-
circuit latchoff circuit is enabled. Even if a short is present
and the short-circuit latchoff is not enabled, a safe, low
output current is provided due to internal current foldback
and actual power wasted is low due to the efficient nature
of the current mode switching regulator.
THEORY AND BENEFITS OF 2-PHASE OPERATION
The LTC1628-SYNC dual high efficiency DC/DC controller
brings the considerable benefits of 2-phase operation to
portable applications for the first time. Notebook comput-
ers, PDAs, handheld terminals and automotive electronics
will all benefit from the lower input filtering requirement,
reduced electromagnetic interference (EMI) and increased
efficiency associated with 2-phase operation.
Why the need for 2-phase operation Up until the LTC1628
family, constant-frequency dual switching regulators op-
erated both channels in phase (i.e., single-phase opera-
tion). This means that both switches turned on at the same
time, causing current pulses of up to twice the amplitude
of those for one regulator to be drawn from the input
capacitor and battery. These large amplitude current pulses
increased the total RMS current flowing from the input
capacitor, requiring the use of more expensive input
capacitors and increasing both EMI and losses in the input
capacitor and battery.
With 2-phase operation, the two channels of the dual-
switching regulator are operated 180 degrees out of
phase. This effectively interleaves the current pulses
drawn by the switches, greatly reducing the overlap time
where they add together. The result s a significant reduc-
tion in total RMS input current, which in turn allows less
expen
sive input capacitors to be used, reduces shielding
requirements for EMI and improves real world operating
efficiency.
Figure 3 compares the input waveforms for a representa-
tive single-phase dual switching regulator to the new
LTC1628-SYNC 2-phase dual switching regulator. An
actual measurement of the RMS input current under these
conditions shows that 2-phase operation dropped the
input current from 2.53A
RMS
to 1.55A
RMS
. While this is an
impressive reduction in itself, remember that the power
losses are proportional to I
RMS2
, meaning that the actual
power wasted is reduced by a factor of 2.66. The reduced
input ripple voltage also means less power is lost in the
input power path, which could include batteries, switches,
trace/connector resistances and protection circuitry. Im-
provements in both conducted and radiated EMI also
directly accrue as a result of the reduced RMS input
current and voltage.
(Refer to Functional Diagram)
OPERATIOU
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LTC1628CG | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數:1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1628CG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數:1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC1628CG#TR | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數:1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1628CG#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數:1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1628CGPBF | 制造商:Linear Technology 功能描述:LTC1628 dual SD PS controller |
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