參數(shù)資料
型號(hào)： MIC4684BM
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, 225 kHz SWITCHING FREQ-MAX, PDSO8
封裝： SOP-8
文件頁(yè)數(shù)： 11/16頁(yè)
文件大?。?/td> 213K
代理商： MIC4684BM
July 2001
11
MIC4684
MIC4684
Micrel
A worst-case rule of thumb is to assume that 80% of the total
output power dissipation is in the MIC4684 (P
D(IC)
) and 20%
is in the diode-inductor-capacitor circuit.
P
D(IC)
= 0.8 P
D
P
D(IC)
= 0.8
×
0.95W
P
D(IC)
= 0.76W
Calculate the worst-case junction temperature:
T
J
= P
D(IC)
θ
JC
+ (T
C
–
T
A
) + T
A(max)
where:
T
J
= MIC4684 junction temperature
P
D(IC)
= MIC4684 power dissipation
θ
JC
= junction-to-case thermal resistance.
The
θ
JC
for the MIC4684
’
s power-SOP-8 is approximately
25
°
C/W.
T
C
=
“
pin
”
temperature measurement taken at the
entry point of pins 2, 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 60
°
C:
T
J
= 0.76
×
25
°
C/W + (41
°
C
–
25
°
C) + 60
°
C
T
J
= 95
°
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 Also see SOA curves on pages 7 through 8.
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.
To minimize stray inductance and ground loops, keep trace
lengths as short as possible. For example, keep D1 close to
pin 1 and pins 2, 6, and 7, keep L1 away from sensitive node
FB, and keep C
IN
close to pin 3 and pins 2, 6, and 7. See
Applications Information: Thermal Considerationsfor ground
plane layout.
The feedback pin should be kept as far way from the switching
elements (usually L1 and D1) as possible.
A circuit with sample layouts are provided. See Figure 7.
Gerber files are available upon request.
Feed Forward Diode
The FF diode (feed forward) provides an external bias source
directly to the main pass element, this reduces V
SAT
thus
allowing the MIC4684 to be used in very low head-room
applications I.E. 5V
IN
to 3.3V
OUT.
L
BS
SW
L1
68
μ
H
IN
EN
FB
GND
2
C
OUT
R1
R2
D1
V
OUT
MIC4684BM
GND
C
IN
V
+4V to +30V
(34V transient)
Power
SOP-8
6
7
5
4
3
1
8
Figure 5. Critical Traces for Layout
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MIC4684BM TR 功能描述:IC REG BUCK ADJ 2A 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:SuperSwitcher™ 標(biāo)準(zhǔn)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(kāi)關(guān):52kHz 電流 - 輸出:1A 同步整流器:無(wú) 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(yīng)商設(shè)備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12
MIC4684YM 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 SO-8 Efficient Simple Buck Regulator (Lead Free) RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)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(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MIC4684YM TR 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 SO-8 Efficient Simple Buck Regulator (Lead Free) RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)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(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MIC4684YM 制造商:Micrel Inc 功能描述:IC VOLTAGE REGULATOR SOIC
MIC4684YM 制造商:Micrel Inc 功能描述:Voltage Regulator IC
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