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參數(shù)資料
| 型號： | LTC1778-1 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Wide Operating Range, No RSENSE Step-Down Controller |
| 中文描述： | 寬工作，無檢測電阻范圍步降控制器 |
| 文件頁數(shù)： | 18/24頁 |
| 文件大?。?/td> | 303K |
| 代理商： | LTC1778-1 |
18
LTC1778/LTC1778-1
1778fa
APPLICATIOU
C
IN
is chosen for an RMS current rating of about 5A at
85
°
C. The output capacitors are chosen for a low ESR of
0.013
to minimize output voltage changes due to induc-
tor ripple current and load steps. The ripple voltage will be
only:
V
OUT(RIPPLE)
=
I
L(MAX)
(ESR)
= (5.1A) (0.013
) = 66mV
However, a 0A to 10A load step will cause an output
change of up to:
V
OUT(STEP)
=
I
LOAD
(ESR) = (10A) (0.013
) = 130mV
An optional 22
μ
F ceramic output capacitor is included to
minimize the effect of ESL in the output ripple. The
complete circuit is shown in Figure 9.
W
U
U
PC Board Layout Checklist
When laying out a PC board follow one of the two sug-
gested approaches. The simple PC board layout requires
a dedicated ground plane layer. Also, for higher currents,
it is recommended to use a multilayer board to help with
heat sinking power components.
Figure 9. Design Example: 2.5V/10A at 250kHz
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
RUN/SS
PGOOD
V
RNG
FCB
I
TH
SGND
I
ON
V
FB
BOOST
TG
SW
PGND
BG
INTV
CC
V
IN
EXTV
CC
LTC1778
+
M2
Si4874
M1
Si4884
L1
1.8
μ
H
D1
B340A
C
OUT1-2
180
μ
F
4V
×
2
C
OUT3
22
μ
F
6.3V
X7R
C
IN
10
μ
F
35V
×
3
V
5V TO 28V
V
2.5V
10A
C
SS
0.1
μ
F
C
500pF
C
C2
100pF
C2
6.8nF
C
VCC
4.7
μ
F
C
F
0.1
μ
F
C
B
0.22
μ
F
R
C
20k
R1
14.0k
R
1.4M
R2
30.1k
R
F
1
D
CMDSH-3
1778 F09
C
IN
: UNITED CHEMICON THCR60EIHI06ZT
C
: CORNELL DUBILIER ESRE181E04B
L1: SUMIDA CEP125-1R8MC-H
R
PG
100k
R3
11k
R4
39k
+
The ground plane layer should not have any traces and
it should be as close as possible to the layer with power
MOSFETs.
Place C
IN
, C
OUT
, MOSFETs, D1 and inductor all in one
compact area. It may help to have some components on
the bottom side of the board.
Place LTC1778 chip with pins 9 to 16 facing the power
components. Keep the components connected to pins
1 to 8 close to LTC1778 (noise sensitive components).
Use an immediate via to connect the components to
ground plane including SGND and PGND of LTC1778.
Use several bigger vias for power components.
Use compact plane for switch node (SW) to improve
cooling of the MOSFETs and to keep EMI down.
Use planes for V
IN
and V
OUT
to maintain good voltage
filtering and to keep power losses low.
Flood all unused areas on all layers with copper. Flood-
ing with copper will reduce the temperature rise of
power component. You can connect the copper areas to
any DC net (V
IN
, V
OUT
, GND or to any other DC rail in
your system).
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| LTC1778EGN | 功能描述:IC REG CTRLR BUCK PWM CM 16-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:2,500 系列:- PWM 型:電流模式 輸出數(shù):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) |
| LTC1778EGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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:2,500 系列:- PWM 型:電流模式 輸出數(shù):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) |
| LTC1778EGN#TR | 功能描述:IC REG CTRLR BUCK PWM CM 16-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:2,500 系列:- PWM 型:電流模式 輸出數(shù):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) |
| LTC1778EGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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:2,500 系列:- PWM 型:電流模式 輸出數(shù):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) |
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