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參數(shù)資料
| 型號： | LTC1628IG#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3 A SWITCHING CONTROLLER, 310 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封裝： | 0.209 INCH, PLASTIC, SSOP-28 |
| 文件頁數(shù)： | 19/32頁 |
| 文件大?。?/td> | 360K |
| 代理商： | LTC1628IG#PBF |
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LTC1628/LTC1628-PG
Design Example
As a design example for one channel, assume VIN =
12V(nominal), VIN = 22V(max), VOUT = 1.8V, IMAX = 5A,
and f = 300kHz.
The inductance value is chosen first based on a 30% ripple
current assumption. The highest value of ripple current
occurs at the maximum input voltage. Tie the FREQSET pin
to the INTVCC pin for 300kHz operation. The minimum
inductance for 30% ripple current is:
I
V
fL
V
L
OUT
IN
=
()( )
–
1
A 4.7
H inductor will produce 23% ripple current and a
3.3
H will result in 33%. The peak inductor current will be
the maximum DC value plus one half the ripple current, or
5.84A, for the 3.3
H value. Increasing the ripple current
will also help ensure that the minimum on-time of 200ns
is not violated. The minimum on-time occurs at maximum
VIN:
t
V
Vf
V
kHz
ns
ON MIN
OUT
IN MAX
()
.
()
==
=
18
22 300
273
The RSENSE resistor value can be calculated by using the
maximum current sense voltage specification with some
accommodation for tolerances:
R
mV
A
SENSE ≤≈
60
584
001
.
Since the output voltage is below 2.4V the output resistive
divider will need to be sized to not only set the output
voltage but also to absorb the SENSE pins specified input
current.
Rk
V
VV
K
V
VV
k
MAX
OUT
124
08
24
08
24
18
32
()
.
.–
.
.– .
=
=
=
Choosing 1% resistors; R1 = 25.5k and R2 = 32.4k yields
an output voltage of 1.816V.
The power dissipation on the top side MOSFET can be
easily estimated. Choosing a Siliconix Si4412DY results
in; RDS(ON) = 0.042, CRSS = 100pF. At maximum input
voltage with T(estimated) = 50
°C:
P
V
CC
V
A
pF
kHz
mW
MAIN =
() +° °
[]
()+ () ( )( )(
)
=
18
22
5
1
0 005 50
25
0 042
1 7 22
5
100
300
220
2
.
(.
)(
–
)
..
A short-circuit to ground will result in a folded back current
of:
I
mV
ns
V
H
A
SC =
+
=
25
001
1
2
200
22
33
32
.
()
.
with a typical value of RDS(ON) and δ = (0.005/°C)(20) =
0.1. The resulting power dissipated in the bottom MOSFET
is:
P
VV
V
A
mW
SYNC =
() ( )
()
=
22
1 8
22
32
11 0042
434
2
–.
..
.
which is less than under full-load conditions.
CIN is chosen for an RMS current rating of at least 3A at
temperature assuming only this channel is on. COUT 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:
VORIPPLE = RESR(IL) = 0.02(1.67A) = 33mVP–P
APPLICATIO S I FOR ATIO
WU
UU
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1628IG-PG | 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:- 標準包裝: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 |
| LTC1628IG-PG#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:- 標準包裝: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 |
| LTC1628IG-PG#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:- 標準包裝: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 |
| LTC1628IG-PG#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:- 標準包裝: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 |
| LTC1628IGSYNC | 制造商:Linear Technology 功能描述: |
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