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参数资料
| 型号： | LTC3823EGN |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 4 A SWITCHING CONTROLLER, 200 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封装： | 0.150 INCH, PLASTIC, SSOP-28 |
| 文件页数： | 13/24页 |
| 文件大小： | 345K |
| 代理商： | LTC3823EGN |
LTC3823
0
3823fb
applications information
Design Example
As a design example, take a supply with the following
specifications: VIN = 5V to 28V (15V nominal), VOUT =
2.5V ±5%, IOUT(MAX) = 10A, f = 320khz. First, calculate
the timing resistor with VON = VOUT:
R
V
kHz
pF
k
ON =
( )(
)( )
=
Ω
2 5
3 2 5 320
10
104
.
and choose the inductor for about 40% ripple current at
the maximum VIN:
L
V
kHz
A
V
= (
)( )( )
=
2 5
320
0 4 10
1
2 5
28
1 7
.
. 77
H
Selecting a standard value of 1.2h results in a maximum
ripple current of:
Δ = (
)
(
)
=
I
V
kHz
H
V
A
L
2 5
320
1 2
1
2 5
28
5 9
.
–
.
Next, choose the synchronous MOSFET switch. Choosing
a Si7892ADP (RDS(ON) = 0.005Ω (NOM) 0.006Ω (MAX),
θJA = 50°C/W) yields a nominal sense voltage of:
VSNS(NOM) = (7A)(1.3)(0.005Ω) = 45mV
TyingVRNGto0.75Vwillsetthecurrentsensevoltagerange
for a nominal value of 75mV with current limit occurring
at 100mV. To check if the current limit is acceptable, as-
sume a junction temperature of about 80°C above a 70°C
ambient with
ρ150°C = 1.5:
I
mV
A
LIMIT ≥
( )
Ω
(
)
+
( ) =
100
1 5 0 006
1
2
5 9
14
.
and double check the assumed TJ in the MOSFET:
P
V
A
W
BOT =
( ) ( )
Ω
(
) =
28
2 5
28
14
1 5 0 006
1 6
2
– .
.
TJ = 70°C + (1.6W)(50°C/W) = 150°C
Because the top MOSFET is on for such a short time,
an Si7342DP RDS(ON)(MAX) = 0.010Ω, CRSS = 120pF,
θJA=53°C/Wwillbesufficient.Checkingitspowerdissipa-
tionatcurrentlimitwith
ρ100°C=1.4:
P
V
A
V
TOP =
( ) ( )
Ω
(
)+
( )( )
2 5
28
14
1 4 0 010
1 7 28
2
.
114 120
320
0 25
0 72
0 97
A
pF
kHz
W
( )(
)(
)
=
+
=
.
TJ = 70°C + (0.97W)(53°C/W) = 121°C
The junction temperature will be significantly less at
nominal current, but this analysis shows that careful at-
tention to heat sinking on the board will be necessary in
this circuit.
CIN is chosen for an RMS current rating of about 3A at
85°C. The output capacitors are chosen for a low ESR
of 0.013
Ω to minimize output voltage changes due to
inductor ripple current and load steps. The ripple voltage
will be only:
ΔVOUT(RIPPLE) = ΔIL(MAX) (ESR)
= (5.9A) (0.013
Ω) = 77mV
however, a 0A to 10A load step will cause an output
change of up to:
ΔVOUT(STEP)=ΔILOAD(ESR)=(10A)(0.013Ω)=130mV
An optional 22F ceramic output capacitor is included
to minimize the effect of ESL in the output ripple. The
complete circuit is shown in Figure 12.
PC Board Layout Checklist
When laying out a PC board follow one of two suggested
approaches. The simple PC board layout requires a dedi-
cated ground plane layer. Also, for higher currents, it is
recommended to use a multilayer board to help with heat
sinking power components.
The ground plane layer should not have any traces and
it should be as close as possible to the layer with power
MOSFETs.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3823EGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3823EGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3823EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC3823EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3823IGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
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