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參數(shù)資料
| 型號： | LTC1625IS |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| 中文描述： | 2 A SWITCHING CONTROLLER, 150 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | PLASTIC, SO-16 |
| 文件頁數(shù)： | 10/24頁 |
| 文件大?。?/td> | 454K |
| 代理商： | LTC1625IS |
10
LTC1625
APPLICATIO
S I
N
FOR
ATIO
U
V
V
IN
W
U
TopDutyCycle
BottomDutyCycle
V
V
V
OUT
IN
OUT
IN
=
=
–
The MOSFET power dissipations at maximum output
current are:
P
V
V
I
R
k V
I
C
f
P
V
V
V
I
R
TOP
OUT
IN
O MAX
(
T TOP
(
DS ON
(
IN
O MAX
(
RSS
BOT
IN
OUT
IN
O MAX
(
T BOT
(
DS ON
(
=
+
=
(
)(
)(
)
)(
)(
)( )
–
(
)(
)(
)
)
)
)
)
)
)
)
2
2
2
ρ
ρ
Both MOSFETs have I
2
R losses and the P
TOP
equation
includes an additional term for transition losses, which are
largest at high input voltages. The constant k = 1.7 can be
used to estimate the amount of transition loss. The bottom
MOSFET losses are greatest at high input voltage or during
a short circuit when the duty cycle is nearly 100%.
Operating Frequency and Synchronization
The choice of operating frequency and inductor value is a
trade-off between efficiency and component size. Low
frequency operation improves efficiency by reducing
MOSFET switching losses, both gate charge loss and
transition loss. However, lower frequency operation
requires more inductance for a given amount of ripple
current.
The internal oscillator runs at a nominal 150kHz frequency
when the SYNC pin is left open or connected to ground.
Pulling the SYNC pin above 1.2V will increase the fre-
quency by 50%. The oscillator will injection lock to a clock
signal applied to the SYNC pin with a frequency between
165kHz and 200kHz. The clock high level must exceed
1.2V for at least 1
μ
s and no longer than 4
μ
s as shown in
Figure 4. The top MOSFET turn-on will synchronize with
the rising edge of the clock.
0
±
1
μ
s
4
μ
s
1625 F04
7V
1.2V
Figure 4. SYNC Clock Waveform
Inductor Value Selection
Given the desired input and output voltages, the inductor
value and operating frequency directly determine the
ripple current:
I
V
f L
( )( )
V
V
L
OUT
OUT
IN
=
–
1
Lower ripple current reduces core losses in the inductor,
ESR losses in the output capacitors and output voltage
ripple. Thus, highest efficiency operation is obtained at
low frequency with small ripple current. To achieve this,
however, requires a large inductor.
A reasonable starting point is to choose a ripple current
that is about 40% of I
O(MAX)
. Note that the largest ripple
current occurs at the highest V
IN
. To guarantee that ripple
current does not exceed a specified maximum, the induc-
tor should be chosen according to:
L
V
f
I
V
V
OUT
L MAX
(
OUT
IN MAX
(
≥
( )(
)
–
)
)
1
Burst Mode Operation Considerations
The choice of R
DS(ON)
and inductor value also determines
the load current at which the LTC1625 enters Burst Mode
operation. When bursting, the controller clamps the peak
inductor current to approximately:
I
mV
R
BURSTPEAK
DS ON
(
(
)
)
=
30
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1625IS#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:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):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(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC1625IS#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN REGULATOR 16-SOIC |
| LTC1625IS#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(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):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 |
| LTC1625IS#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(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):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 |
| LTC1625ISPBF | 制造商:Linear Technology 功能描述:No RSENSE Current Mode Regulator SOIC16 |
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