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參數(shù)資料
| 型號： | L4990AD |
| 廠商： | 意法半導體 |
| 英文描述： | PRIMARY CONTROLLER |
| 中文描述： | 主控制器 |
| 文件頁數(shù)： | 18/24頁 |
| 文件大?。?/td> | 322K |
| 代理商： | L4990AD |
Layout hints.
Generally speaking a proper cir-
cuitboard layout is vital for correct operationbut is
not an easy task. Careful component placing, cor-
rect traces routing, appropriate traces widths and,
in case of high voltages,compliancewith isolation
distances are the major issues. The L4990 eases
this task by putting two pins at disposal for sepa-
rate current returns of bias (SGND) and switch
drive currents (PGND) The matter is complexand
only fewimportant points will be herereminded.
1) All current returns (signal ground, power
ground, shielding, etc.) should be routed sepa-
rately and should be connectedonly at a single
ground point.
2) Noise coupling can be reduced by minimizing
the area circumscribed by current loops. This
applies particularly to loops where high pulsed
currentsflow.
3) For high current paths, the traces should be
doubled on the other side of thePCB whenever
possible: this will reduce both the resistance
and the inductanceof the wiring.
4) Magnetic field radiation (and stray inductance)
can be reduced by keeping all traces carrying
switched currents as short as possible.
5) In general, traces carrying signal currents
should run far from traces carrying pulsed cur-
rents or with quickly swinging voltages. From
this viewpoint, particular care should be taken
of the high impedance points (current sense in-
put, feedback input, ...). It could be a good idea
to route signal traces on one PCB side and
power traceson the other side.
6) Provide adequate filtering of some crucial
points of the circuit, such as voltage refer-
ences, IC’s supplypins, etc.
APPLICATION IDEAS
Here follows a seriesof ideas/suggestionsaimed at
either improving performance or solving common
applicationproblemsof L4990-basedsupplies.
D97IN504
L4990
PGND
ISEN
OUT
V
C
SGND
V
IN
ISOLATION
BOUNDARY
10
9
13
11
12
Figure 33. Isolated MOSFET Drive & Current TransformerSensing in 2-switch Topologies.
L4990
12
V
REF
T
STD1NB50-1
V
CC
V
IN
22V
D97IN505A
2.2M
33K
SELF-SUPPLY
WINDING
8
4
11
47K
Figure 34. Low consumptionstart-up
L4990 - L4990A
18/24
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PDF描述 |
|---|---|
| L4990D | PRIMARY CONTROLLER |
| L4992 | TRIPLE OUTPUT POWER SUPPLY CONTROLLER |
| L5170 | CAP CER 47000PF 50V X7R 0805 |
| L5170A | OCTAL LINE DRIVER |
| L5170D | OCTAL LINE DRIVER |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| L4990D | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:PRIMARY CONTROLLER |
| L4991 | 功能描述:TEST COIL FOR REED SWITCH, 1PC RoHS:是 類別:開關 >> 配件 系列:- 標準包裝:100 系列:- 其它名稱:886.0007886.0007-ND |
| L4992 | 制造商:STMicroelectronics 功能描述: 制造商:STMicroelectronics 功能描述:VOLT SUPERVISOR CNTRLR 5.1V/3.3V 32TQFP - Trays |
| L4993 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Low drop voltage regulator |
| L4993D | 功能描述:低壓差穩(wěn)壓器 - LDO Low drop voltage regulator RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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