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參數(shù)資料
| 型號： | LTC3727EG-1 |
| 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： | 3 A SWITCHING CONTROLLER, 580 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封裝： | 5.30 MM, PLASTIC, SSOP-28 |
| 文件頁數(shù)： | 25/32頁 |
| 文件大小： | 398K |
| 代理商： | LTC3727EG-1 |
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LTC3727/LTC3727-1
3727f
Design Example
As a design example for one channel, assume V
IN
=
24V(nominal), V
IN
= 30V(max), V
OUT
= 12V, I
MAX
= 5A and
f = 250kHz.
The inductance value is chosen first based on a 40% ripple
current assumption. The highest value of ripple current
occurs at the maximum input voltage. Tie the PLLFLTR pin
to the SGND pin for 250kHz operation. The minimum
inductance for 40% ripple current is:
I
V
f L
( )( )
V
V
L
OUT
OUT
IN
=
–
1
A 14
μ
H inductor will result in 40% ripple current. The peak
inductor current will be the maximum DC value plus one
half the ripple current, or 6A, for the 14
μ
H value.
The R
SENSE
resistor value can be calculated by using the
maximum current sense voltage specification with some
accommodation for tolerances:
R
mV
A
6
SENSE
≤
≈
90
0 015
.
Choosing 1% resistors; R1 = 20k and R2 = 280k yields an
output voltage of 12V.
The power dissipation on the top side MOSFET can be
easily estimated. Choosing a Siliconix Si4412DY results
in; R
DS(ON)
= 0.042
, C
RSS
= 100pF. At maximum input
voltage with T(estimated) = 50
°
C:
P
V
V
C
C
V
A
pF
kHz
mW
MAIN
=
( )
5
+
°
°
[
]
(
)
+
) (
)(
)(
)
=
12
30
0 042
664
1
(0 005 50
25
1 7 30
.
5
100
250
2
)(
–
)
.
A short-circuit to ground will result in a folded back current
of:
I
mV
ns
14
V
H
A
SC
=
+
μ
=
45
0 015
.
1
2
200
30
(
3 2
.
)
with a typical value of R
DS(ON)
and
δ
= (0.005/
°
C)(20) =
0.1. The resulting power dissipated in the bottom MOSFET
is:
V
V
V
mW
=
126
P
A
SYNC
=
(
) (
)
30
12
30
3 2
.
1 1 0 042
.
2
–
.
which is less than under full-load conditions.
C
IN
is chosen for an RMS current rating of at least 3A at
temperature assuming only this channel is on. C
OUT
is
chosen with an ESR of 0.02
for low output ripple. The
output ripple in continuous mode will be highest at the
maximum input voltage. The output voltage ripple due to
ESR is approximately:
V
ORIPPLE
= R
ESR
(
I
L
) = 0.02
(2A) = 40mV
P–P
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC3727. These items are also illustrated graphically in
the layout diagram of Figure 10. The Figure 11 illustrates
the current waveforms present in the various branches of
the 2-phase synchronous regulators operating in the
continuous mode. Check the following in your layout:
1. Are the top N-channel MOSFETs M1 and M3 located
within 1cm of each other with a common drain connection
at C
IN
Do not attempt to split the input decoupling for the
two channels as it can cause a large resonant loop.
APPLICATIOU
W
U
U
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3727EG-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 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 |
| LTC3727EG-1#TR | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 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 |
| LTC3727EG-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 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 |
| LTC3727EG-1PBF | 制造商:Linear Technology 功能描述:DC-DC Controller Dual Step-Dn 36V SSOP28 |
| LTC3727EGPBF | 制造商:Linear Technology 功能描述:Dual Sync Buck Sw Vreg Controller SSOP28 |
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