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參數資料
| 型號： | LT1376CN8-5#TR |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3 A SWITCHING REGULATOR, 570 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封裝： | 0.300 INCH, PLASTIC, DIP-8 |
| 文件頁數： | 2/28頁 |
| 文件大小： | 500K |
| 代理商： | LT1376CN8-5#TR |
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10
LT1375/LT1376
13756fd
APPLICATIONS INFORMATION
WU
U
pin when output voltage is low. The equivalent circuitry is
shown in Figure 2. Q1 is completely off during normal
operation. If the FB pin falls below 1V, Q1 begins to
conduct current and reduces frequency at the rate of
approximately 5kHz/
A. To ensure adequate frequency
foldback (under worst-case short-circuit conditions), the
external divider Thevinin resistance must be low enough
to pull 150
A out of the FB pin with 0.6V on the pin (RDIV
≤ 4k). The net result is that reductions in frequency and
current limit are affected by output voltage divider imped-
ance. Although divider impedance is not critical, caution
should be used if resistors are increased beyond the
suggested values and short-circuit conditions will occur
with high input voltage. High frequency pickup will in-
crease and the protection accorded by frequency and
current foldback will decrease.
MAXIMUM OUTPUT LOAD CURRENT
Maximum load current for a buck converter is limited by
the maximum switch current rating (IP) of the LT1376.
This current rating is 1.5A up to 50% duty cycle (DC),
decreasing to 1.35A at 80% duty cycle. This is shown
graphically in Typical Performance Characteristics and as
shown in the formula below:
IP = 1.5A for DC ≤ 50%
IP = 1.65A – 0.15 (DC) – 0.26 (DC)2 for 50% < DC < 90%
DC = Duty cycle = VOUT/VIN
Example: with VOUT = 5V, VIN = 8V; DC = 5/8 = 0.625, and;
ISW(MAX) = 1.64 – 0.15 (0.625) – 0.26 (0.625)2 = 1.44A
Current rating decreases with duty cycle because the
LT1376 has internal slope compensation to prevent cur-
rent mode subharmonic switching. For more details, read
Application Note 19. The LT1376 is a little unusual in this
regard because it has nonlinear slope compensation which
gives better compensation with less reduction in current
limit.
Maximum load current would be equal to maximum
switch current
for an infinitely large inductor, but with
finite inductor size, maximum load current is reduced by
one-half peak-to-peak inductor current. The following
formula assumes continuous mode operation, implying
that the term on the right is less than one-half of IP.
IOUT(MAX) =
Continuous Mode
For the conditions above and L = 10
H,
I
A
OUT MAX
( )
=
()
()
()
=
=
144
58 5
2 10
500 10
8
144 019
125
53
.
..
.
At VIN = 15V, duty cycle is 33%, so IP is just equal to a fixed
1.5A, and IOUT(MAX) is equal to:
15
515 5
2 10
500 10
15
15 033
117
53
.
..
.
()
()
()
=
=
A
Note that there is less load current available at the higher
input voltage because inductor ripple current increases.
This is not always the case. Certain combinations of
inductor value and input voltage range may yield lower
available load current at the lowest input voltage due to
reduced peak switch current at high duty cycles. If load
current is close to the maximum available, please check
maximum available current at both input voltage ex-
tremes. To calculate actual peak switch current with a
given set of conditions, use:
II
VV
V
Lf V
SW PEAK
OUT
IN
OUT
IN
( ) =+
()
()( )( )
2
For lighter loads where discontinuous operation can be
used, maximum load current is equal to:
IOUT(MAX) =
Discontinuous mode
IP ()
()
()( )( )
VV
V
Lf V
OUT
IN
OUT
IN
2
If L V
VV
V
P
OUT
IN
OUT
() ( )( )( )
()
()
2
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LT1376CN8PBF | 制造商:Linear Technology 功能描述:LT1376CN8PBF |
| LT1376CS | 功能描述:IC REG BUCK ADJ 1.5A 16SOIC 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: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 |
| LT1376CS#PBF | 功能描述:IC REG BUCK ADJ 1.5A 16SOIC 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:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數: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 |
| LT1376CS#TR | 功能描述:IC REG BUCK ADJ 1.5A 16SOIC 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: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 |
| LT1376CS#TRPBF | 功能描述:IC REG BUCK ADJ 1.5A 16SOIC 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:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數: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 |
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