參數(shù)資料
型號： MIC4690BM
廠商： MICREL INC
元件分類： 穩(wěn)壓器
英文描述： 150000 SYSTEM GATE 2.5 VOLT FPGA - NOT RECOMMENDED for NEW DESIGN
中文描述： SWITCHING REGULATOR, 550 kHz SWITCHING FREQ-MAX, PDSO8
封裝： SOP-8
文件頁數(shù)： 9/12頁
文件大?。?/td> 225K
代理商： MIC4690BM
June 2001
9
MIC4690
MIC4690
Micrel
When designing with the MIC4690, it is a good practice to
connect pins 5 through 8 to the largest ground plane that is
practical for the specific design.
Checking the Maximum Junction Temperature:
For this example, with an output power (P
OUT
) of 5W, (5V
output at 1A maximum with V
IN
= 12V) and 50
°
C maximum
ambient temperature, what is the maximum junction tem-
perature
Referring to the
“
Typical Characteristics: 5V Output Effi-
ciency
”
graph, read the efficiency (
η
) for 1A output current at
V
IN
= 12V or perform you own measurement.
η
= 75%
The efficiency is used to determine how much of the output
power (P
OUT
) is dissipated in the regulator circuit (P
D
).
P =P
P
OUT
η
OUT
P =5W
0.75
5W
P
D
= 1.67W
A worst-case rule of thumb is to assume that 80% of the total
output power dissipation is in the MIC4690 (P
D(IC)
) and 20%
is in the diode-inductor-capacitor circuit.
P
D(IC)
= 0.8 P
D
P
D(IC)
= 0.8
×
1.67W
P
D(IC)
= 1.336W
Calculate the worst-case junction temperature:
T
J
= P
D(IC)
θ
JC
+ (T
C
–
T
A
) + T
A(max)
where:
T
J
= MIC4690 junction temperature
P
D(IC)
= MIC4690 power dissipation
θ
JC
= junction-to-case thermal resistance.
The
θ
JC
for the MIC4690
’
s power-SOP-8 is approximately
20
°
C/W.
T
C
=
“
pin
”
temperature measurement taken at the
entry point of pins 6 or 7
T
A
= ambient temperature
T
A(max)
= maximum ambient operating temperature
for the specific design.
Calculating the maximum junction temperature given a
maximum ambient temperature of 50
°
C:
T
J
= 1.336W
×
20
°
C/W + (63
°
C
–
25
°
C) + 50
°
C
T
J
= 114.72
°
C
This value is within the allowable maximum operating junc-
tion temperature of 125
°
C as listed in
“
Operating Ratings.
”
Typical thermal shutdown is 160
°
C and is listed in
“
Electrical
Characteristics.
”
Layout Considerations
Layout is very important when designing any switching regu-
lator. Rapidly changing currents through the printed circuit
board traces and stray inductance can generate voltage
transients which can cause problems.
θ
JA
θ
JC
θ
CA
AMBENT
printed circuit board
ground plane
heat sink area
SOP-8
Figure 2. Power SOP-8 Cross Section
Thermal Considerations
The MIC4690 SuperSwitcher
features the power-SOP-8.
This package has a standard 8-lead small-outline package
profile, but with much higher power dissipation than a stan-
dard SOP-8. Micrel's MIC4690 SuperSwitcher
family are
the first dc-to-dc converters to take full advantage of this
package.
The reason that the power SOP-8 has higher power dissipa-
tion (lower thermal resistance) is that pins 5 through 8 and the
die-attach paddle are a single piece of metal. The die is
attached to the paddle with thermally conductive adhesive.
This provides a low thermal resistance path from the junction
of the die to the ground pins. This design significantly im-
proves package power dissipation by allowing excellent heat
transfer through the ground leads to the printed circuit board.
One limitation of the maximum output current on any MIC4690
design is the junction-to-ambient thermal resistance (
θ
JA
) of
the design (package and ground plane).
Examining
θ
JA
in more detail:
θ
JA
= (
θ
JC
+
θ
CA
)
where:
θ
JC
= junction-to-case thermal resistance
θ
CA
= case-to-ambient thermal resistance
θ
JC
is a relatively constant 20
°
C/W for a power SOP-8.
θ
CA
is dependent on layout and is primarily governed by the
connection of pins 5 though 8 to the ground plane. The
purpose of the ground plane is to function as a heat sink.
θ
JA
is ideally 63
°
C/W, but will vary depending on the size of
the ground plane to which the power SOP-8 is attached.
Determining Ground-Plane Heat-Sink Area
There are two methods of determining the minimum ground
plane area required by the MIC4690.
Quick Method
Make sure that MIC4690 pins 5 though 8 are connected to a
ground plane with a minimum area of 6cm
2
. This ground
plane should be as close to the MIC4690 as possible. The
area may be distributed in any shape around the package or
on any pcb layer as long as there is good thermal contact to
pins 5 though 8 This ground plane area is more than
sufficient for most designs.
相關PDF資料
PDF描述
MIC4720 400 W Transient Voltage Suppressor, SOD123W (SOD2 FlatPower), Reel Pack, SMD
MIC4720BML 400 W Transient Voltage Suppressor, SOD123W (SOD2 FlatPower), Reel Pack, SMD
MIC4720YML 400 W Transient Voltage Suppressor, SOD123W (SOD2 FlatPower), Reel Pack, SMD
MIC4720YMME Dual UART with 16 bytes of transmit and receive FIFOs and infrared (IrDA) encoder/decoder, SOT313-2 (LQFP48), Tray Pack, Bakeable, Single
MIC4721 Quad UART with 16-byte FIFO and infrared (IrDA) encoder/decoder, SOT315-1 (LQFP80), Reel Dry Pack, SMD, 13",Turned
相關代理商/技術參數(shù)
參數(shù)描述
MIC4690BM TR 功能描述:IC REG BUCK ADJ 1A 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:SuperSwitcher™ 標準包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關:52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應商設備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12
MIC4690YM 功能描述:直流/直流開關調節(jié)器 SO-8 500KHz Simple Buck Regulator (Lead Free) RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MIC4690YM TR 功能描述:直流/直流開關調節(jié)器 SO-8 500KHz Simple Buck Regulator (Lead Free) RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MIC4690YM 制造商:Micrel Inc 功能描述:Voltage Regulator IC
MIC4690YMG11 制造商:Micrel 功能描述:The Micrel MIC4690YMG11 is a 1A Synchronous Buck Regulator.
發(fā)布緊急采購，3分鐘左右您將得到回復。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*