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參數(shù)資料
| 型號(hào)： | LT3433 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | High Voltage Step-Up/Step-Down DC/DC Converter |
| 中文描述： | 高電壓降壓型DC / DC變換器 |
| 文件頁(yè)數(shù)： | 9/12頁(yè) |
| 文件大小： | 183K |
| 代理商： | LT3433 |
9
LT3433
3433ia
The LT3433 contains circuitry to eliminate the current limit
reduction associated with slope-compensation, or anti-
slope compensation. As the slope compensation ramp is
added to the sensed current, a similar ramp is added to the
current limit threshold reference. The end result is that
current limit is not compromised so the LT3433 can
provide full power regardless of required duty cycle.
Mode Switching
The LT3433 senses operational duty cycle by directly
monitoring V
IN
and V
OUT
. Voltage drops associated with
pass and catch diodes are estimated internally such that
mode switching occurs when the duty cycle required for
continuous buck operation is greater than 75%. If such a
condition exists, a second switch is enabled during the
switch on time, changing operation to a dual switch
bridged configuration. Because the voltage available across
the switched inductor is greater in bridged mode, duty
cycle will decrease.
The output current in bridged mode is not continuous, so
switch currents are considerably higher than while oper-
ating in buck mode. In order to maximize available output
power, continuous operation and low ripple currents are
recommended. Switch currents will increase by a factor of
1/(1 – DC) during bridged mode, so this mode of operation
is typically the gating item for converter drive capability.
I
OUT(MAX)
= I
SW(MAX)
(1 –DC)
= [0.5A – (
I
L
/ 2)] (1 – DC)
where
I
L
is the ripple current in the inductor.
It is also important to note that I
OUT
cannot be considered
equivalent to I
LOAD
during bridged operation. Most of the
converter’s switch drive power is derived from the gener-
ated output supply, so I
OUT
must also accommodate this
current requirement. During single-switch buck opera-
tional conditions, switch drive current is negligible in
terms of output current; however, during bridged opera-
tion, these currents can become significant. These output
derived switch drive currents will increase the current
loading on V
IN
by the same 1/(1 – DC) factor as the switch
currents. As maximum switch current is referenced to that
coming from the V
IN
supply, the available maximum
switch current will be reduced by this required drive
current.
I
DRIVE
= DC 2 I
SW(MAX)
I
SWDRIVE(MAX)
Using 50mA/A for the required drive current for each
switch yields the portion of switch current used to drive
the switches is:
I
SW(DRIVE)
= DC 2 I
SW(MAX)
0.05/(1 – DC)
Removing drive currents from the available maximum
switch current yields:
I
SW(MAX)
' = I
SW(MAX)
[1 – DC 2 I
SW(MAX)
0.05/(1 – DC)]
where I
SW(MAX)
' is maximum switch current available to
the load during bridged operation. The maximum load
current can then be calculated as:
I
LOAD(MAX)
= I
SW(MAX)
' (1 – DC)
which reduces to:
I
LOAD(MAX)
= [0.5A – (
I
L
/2)] (1 – 1.1 DC)
Design Equations
APPLICATIOU
W
U
U
SW_H
LT3433
V
IN
V
OUT
3433 AI01
SW_L
L
Constants:
V
SWH
= voltage drop across boosted switch
V
SWL
= voltage drop across grounded switch
V
F
= forward drop of external Schottky diodes
f
0
= operating frequency
Duty Cycle (continuous operation):
DC
BUCK
= (V
OUT
+ 2V
F
)/(V
IN
– V
SWH
+ V
F
)
DC
BRIDGED
= (V
OUT
+ 2V
F
)/(V
OUT
+ V
IN
+ 2V
F
– V
SWH
– V
SWL
)
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT3433_1 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Voltage Step-Up/Step-Down DC/DC Converter |
| LT3433EFE | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP RoHS:否 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:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LT3433EFE#PBF | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP 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:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁(yè)面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LT3433EFE#TR | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP RoHS:否 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:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LT3433EFE#TRPBF | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP 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:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
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