- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377705 > LT1507C (Linear Technology Corporation) RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS PDF資料下載
參數(shù)資料
| 型號： | LT1507C |
| 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(shù)： | 15/20頁 |
| 文件大?。?/td> | 343K |
| 代理商： | LT1507C |
15
LT1507
APPLICATIO
S I
FOR
ATIO
U
is not a problem, but it should be noted that for equal case
size the ripple current rating and ESR of higher voltage
capacitors will be somewhat worse. The lower input
operating voltages of the LT1507 allow considerable
derating of capacitor voltage. If solid tantalum units are
used, it would be wise to use units rated at 25V or more,
as long as ripple current requirements are met. Design
Note 122 discusses the problem of showing typical input
capacitor surges that occur when batteries or adapters are
hot plugged to typical regulator systems.
A new capacitor type known as OS-CON uses a “semicon-
ductor” dielectric to achieve extremely low ESR and high
ripple current rating. These are ideal for input bypassing
because they are not surge sensitive. They are not sug-
gested for output capacitors because the very low ESR
may present loop stability problems. Price and size (height)
are issues to be considered. The original manufacturer is
Sanyo but there are now additional sources.
Larger capacitors may be necessary when the input volt-
age is very close to the minimum specified on the data
sheet. A 5
μ
F ceramic input capacitor for instance, moves
at about 0.1V/
μ
s during switch ON time when load current
is 1A, creating a ripple voltage due to reactance. This is in
addition to the ripple caused by capacitor ESR. Physically
larger input capacitors will have more capacitance (less
reactance) and lower ESR. Small voltage dips during
switch ON time are not normally a problem, but at very low
input voltage they may cause erratic operation because the
input voltage drops below the minimum specification.
Problems can also occur if the input to output voltage
differential is near minimum.
W
U
U
Minimum Input Voltage (After Start-Up)
Minimum input voltage to make the LT1507 “run” cor-
rectly is typically 3.6V, but to regulate the output, a buck
converter input voltage must always be higher than the
output voltage. To calculate minimum operating input
voltage, switch voltage loss and maximum duty cycle
must be taken into account. With the LT1507 there is the
additional consideration of proper operation of the boost
circuit. The boost circuit allows the power switch to
saturate for high efficiency, but it also sometimes results
in a start-up or low current operating voltage that is 0.5V
to 1.5V higher than the standard running voltage, espe-
cially at light loads. An approximate formula to calculate
minimum running voltage at load currents above 100mA
is:
V
I
IN MIN
(
)
.
0 85
With V
OUT
= 3.3V and I
OUT
= 0.1A, this formula yields
V
IN(MIN)
= 3.9V. Increasing load current to 1A raises
minimum input to 4.2V. For start-up and operation at light
loads, see the next section.
V
I
mA
OUT
OUT
OUT
(
)0 3
)
(
)
=
+
≥
100
Minimum Start-Up Voltage and Operation
at Light Loads
The boost capacitor supplies current to the BOOST pin
during switch ON time. This capacitor is recharged only
during switch OFF time. Under certain conditions of light
load and low input voltage, the capacitor may not be fully
recharged during the relatively short OFF time. This causes
the boost voltage to collapse and minimum input voltage
is increased. Start-up voltage at light loads is higher than
normal running voltage for the same reasons. Figure 5
shows minimum input voltage for a 3.3V output, both for
start-up and for normal operation. This graph indicates
that a 5V to 3.3V converter with 4.7V minimum input
voltage, will not start correctly below a 40mA load current
and will not run correctly below a 4mA load current. If
minimum load current is less than 50mA, a preload should
be added or the circuit in Figure 6 can be used.
LOAD CURRENT (mA)
1
I
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
10
100
1000
LT1400 GXX
VALID ONLY FOR V
OUT
= 3.3V
MINIMUM VOLTAGE
TO START WITH
STANDARD CIRCUITS
MINIMUM VOLTAGE
TO START WITH
PNP ADDED
MINIMUM VOLTAGE
TO RUN WITH
STANDARD CIRCUIT
MINIMUM VOLTAGE
TO RUN WITH
PNP ADDED
MINIMUM VOLTAGE
TO RUN WITH
PNP ADDED
OUT
= 3.3V
相關PDF資料 |
PDF描述 |
|---|---|
| LT1507CN8 | Octal D-Type Edge-Triggered Flip-Flops With 3-State Outputs 24-SOIC 0 to 70 |
| LT1507CN8-3.3 | Octal D-Type Edge-Triggered Flip-Flops With 3-State Outputs 24-SOIC 0 to 70 |
| LT1507CS8 | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| LT1507CS8-3.3 | Octal D-Type Edge-Triggered Flip-Flops With 3-State Outputs 24-SO 0 to 70 |
| LT1507I | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LT1507CN8 | 功能描述:IC REG BUCK ADJ 1.5A 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝: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:- 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) 供應商設備封裝:10-MSOP 裸露焊盤 |
| LT1507CN8#PBF | 功能描述:IC REG BUCK ADJ 1.5A 8DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關:52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應商設備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12 |
| LT1507CN8-3.3 | 功能描述:IC REG BUCK 3.3V 1.5A 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝: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:- 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) 供應商設備封裝:10-MSOP 裸露焊盤 |
| LT1507CN8-3.3#PBF | 功能描述:IC REG BUCK 3.3V 1.5A 8DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝: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: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) 供應商設備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LT1507CS8 | 功能描述:IC REG BUCK ADJ 1.5A 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 設計資源:Design Support Tool 標準包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:100mA 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:SOT-23-5 細型，TSOT-23-5 包裝:剪切帶 (CT) 供應商設備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
發(fā)布緊急采購，3分鐘左右您將得到回復。