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參數資料
| 型號： | LTC1143CS |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Enclosures; Leaded Process Compatible:Yes; Peak Reflow Compatible (260 C):Yes RoHS Compliant: Yes |
| 中文描述： | SWITCHING CONTROLLER, 400 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCH, PLASTIC, SO-16 |
| 文件頁數： | 9/20頁 |
| 文件大?。?/td> | 372K |
| 代理商： | LTC1143CS |
9
LTC1143/LTC1143L
LTC1143L-ADJ
APPLICATIO
S I
FOR
ATIO
U
W
U
U
MAXIMUM OUTPUT CURRENT (A)
0
R
S
)
0.20
0.15
0.10
0.05
0
4
1143 F02
1
2
3
5
Figure 2. Selecting R
SENSE
The load current below which Burst Mode operation
commences, I
BURST
, and the peak short circuit current,
I
SC(PK)
, both track I
MAX
. Once R
SENSE
has been chosen,
I
BURST
and I
SC(PK)
can be predicted from the following:
I
BURST
≈
15mV
R
SENSE
I
SC(PK)
= 150mV
R
SENSE
The LTC1143 series automatically extends t
OFF
during a
short circuit to allow sufficient time for the inductor
current to decay between switch cycles. The resulting
I
SC(AVG)
to be reduced to approximately I
MAX
.
L and C
T
Selection for Operating Frequency
Each regulator section of the LTC1143 series uses a
constant off-time architecture with t
OFF
determined by an
external timing capacitor C
T
. Each time the P-channel
MOSFET switch turns on the voltage on C
T
is reset to
approximately 3.3V. During the off-time, C
T
is discharged
by a current that is proportional to V
OUT
. The voltage on C
T
is analogous to the current in inductor L, which likewise
decays at a rate proportional to V
OUT
. Thus the inductor
value must track the timing capacitor value.
The value of C
T
is calculated from the desired continuous
mode operating frequency:
C
f
V
V
+
V
V
T
IN
OUT
IN
D
=
1
1 3 10
4
.
where V
D
is the drop across the diode.
A graph for selecting C
T
versus frequency including the
effects of input voltage is given in Figure 3.
As the operating frequency is increased the gate charge
losses will be higher, reducing efficiency (see Efficiency
Considerations). The complete expression for operating
frequency of the circuit in Figure 1 is given by:
f
t
V
V
OFF
OUT
IN
≈
1
1
where:
t
C
V
V
OFF
T
REG
OUT
=
1 3 10
4
.
V
REG
is the desired output voltage (i.e., 5V, 3.3V). V
OUT
is the measured output voltage. Thus V
REG
/V
OUT
= 1 in
regulation.
Note that as V
IN
decreases, the frequency decreases.
When the input-to-output voltage differential drops below
1.5V for a particular section, the LTC1143 series reduces
t
OFF
in that section by increasing the discharge current in
C
T
. This prevents audible operation prior to dropout.
FREQUENCY (kHz)
0
C
50
100
150
200
LTC1143 F03
250
1000
800
600
400
200
0
300
V
IN
= 12V
V
IN
= 10V
V
IN
= 7V
V
SENSE
= V
OUT
= 5V
Figure 3. Timing Capacitor Value
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LTC1143CS#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC 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:2,500 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1143CS#TR | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC 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:2,500 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1143CS#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC 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:2,500 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1143L | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual High Efficiency SO-16 Step-Down Switching Regulator Controllers |
| LTC1143L-ADJ | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual High Efficiency SO-16 Step-Down Switching Regulator Controllers |
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