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參數(shù)資料
| 型號： | A8287SLB |
| 廠商： | Allegro MicroSystems, Inc. |
| 英文描述： | LNB Supply and Control Voltage Regulator |
| 中文描述： | LNB電源和控制穩(wěn)壓器 |
| 文件頁數(shù)： | 12/17頁 |
| 文件大?。?/td> | 527K |
| 代理商： | A8287SLB |
12
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
D
P
2
A8285/A8287
LNB Supply and Control Voltage Regulator
Example.
Given:
V
IN
= 12 V
V
OUT
= 18 V
I
LOAD
= 500 mA
Two-layer PCB.
Maximum ambient temperature = 70 oC,
Maximum allowed junction temperature= 110 oC
Assume:
V
D
= 0.4 V and select
V
REG
= 0.7 V
D = 1 – (12 / (18 + 0.4 + 0.7) = 0.37
I
PK
= 18
×
0.5 / (0.89
×
12) = 843 mA
R
DSBOOST
= 0.5 + (110
– 25)
×
2.7 m
= 730 m
Worst case losses can now be estimated:
Pd_Rds = 0.843
2
×
0.73
×
0.37 = 192 mW
Pd_sw = 70 mW
Pd_control = 15 mA
×
V
IN
= 180 mW
Pd_lin = 0.7
×
0.5 = 350 mW
and therefore
P
TOT
= 0.192 + 0.07 + 0.18 + 0.35 = 0.792 W
The thermal resistance required is:
(110 – 70) / 0.792 = 50.5oC/W
Note: For the case of the A8287, the area of copper required
on each layer is approximately 1.2 in
2
.
Layout Considerations
Recommended placement of critical components and track-
ing for the A8287 is shown in the PCB Layout digagram on
the following page. It is recommended that the ground plane
be separated into two areas, referred to as
switcher
and
con-
trol,
on each layer using a ground plane. With respect to the
input connections, VIN and 0V, the two ground plane areas
are isolated as shown by the dotted line and the ground plane
areas are connected together at pins 6, 7, 18, and 19. This
con
fi
guration minimizes the effects of the noise produced by
the switcher on the noise-sensitive sections of the circuit.
Power-related tracking from INPUT to L1, LNB (pin 17) to
L2 then OUTPUT, LX (pin 20) to D1 and L1, VBOOST (pin
23) to C4 and D1 should be as short and wide as possible.
Power components such as the boost diode D1, inductor
L1, and input/output capacitors C1, C9, and C4, should be
located as close as possible to the IC. The DiSEqC inductor
L2 should be located as far away from the boost inductor L1
to prevent potential magnetic crosstalk.
The
fi
lter capacitor (VREG), charge pump capacitor (VCP),
ac coupling tone detect capacitor (TDI), tone pull-down
resistor (TOUT), and LNB output capacitor/protection diode
(LNB) should be located directly next to the appropriate pin.
Where a PCB with two or more layers is used, it is recom-
mended that four thermal vias be deployed as shown in the
PCB Layout diagram. Note that adding additional vias does
not enhance the thermal characteristics.
40
50
60
70
80
90
100
0
1
2
3
4
2
)
Area (in.
2
)
T
0
C
One side Copper
Two side Copper
40
50
60
70
80
0
1
2
3
4
2
)
Area (in.
2
)
T
0
C
One side Copper
Two side Copper
R
JA
vs. Area Charts
A8285, 16-Pin SOIC
A8287, 24-Pin SOIC
T
(
T
(
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| A8287SLB-T | 制造商:Allegro MicroSystems LLC 功能描述: |
| A8287SLBTR | 功能描述:IC REG LNB SUPPLY/CTRL 24-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
| A8287SLBTR-T | 功能描述:IC LNB SUPPLY/VOLTAGE REG 24SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:控制器，DSP 輸入電壓:4.5 V ~ 25 V 輸出數(shù):2 輸出電壓:最低可調(diào)至 1.2V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:30-TFSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:30-TSSOP 包裝:帶卷 (TR) |
| A8290 | 制造商:ALLEGRO 制造商全稱:Allegro MicroSystems 功能描述:Single LNB Supply and Control Voltage Regulator |
| A8290SETTR-T | 功能描述:IC VOLTAGE REG SGL LNB 28-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
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