Analog Integrated Circuit Device Data
Freescale Semiconductor
17
34652
FUNCTIONAL DEVICE OPERATION
PROTECTION FEATURES
rchived by Freescale Semiconductor, Inc., 2008
The power dissipation in the device can be calculated as
follows:
P = I
2
(LOAD)
*
R
DS(ON)
OR
P = [T
J
(max) - T
A
(max)] / R
窲A
Combining the two equations:
I
2
(LOAD)
= [ T
J
(max) - T
A
(max)] / [R
窲A
*
R
DS(ON)
] Eq 1
For example:
T
A
(max) = 55癈
R
窲A
= 51癈/W for a four-layer board
R
DS(ON)
= 0.251 ?at high temperatures
Then:
I
2
(LOAD)
= [ T
J
(max) - 55癈] / [51癈/W
*
0.251
I
2
(LOAD)
= [ T
J
(max) - 55癈] / 12.80癈 / A
2
So if the overcurrent limit is 2.0 A, then the maximum
junction temperature is 106.2癈, which is well below the
thermal shutdown temperature that is allowed.
The previous explanation applies to steady state power
when the device is in normal operation. During the charging
process, the power is dominated by the I * V across the Power
MOSFET. When charging starts, the power in the Power
MOSFET rises up and reaches a maximum value of I * V, then
quickly ramps back down to the steady state level in a period
governed by the size of the loads input capacitor that is being
charged and by the value of the charging current limit I
CHG
.
In this case the instantaneous power dissipation is much
higher than the steady state case, but it is on for a very short
time.
For example:
I
CHG
= 100 mA, the default value
C
LOAD
= 400 ?/SPAN>F, a very large capacitor
V
PWR
= 80 V, worst case
Then:
The power pulse magnitude = I
CHG
*
V
PWR
= 8.0 W
The power pulse duration = C
LOAD
*
V
PWR
/ I
CHG
= 320 ms
Figure 17
displays the temperature profile of the device
under the instantaneous power pulse during the charging
process. Table 5
depicts thermal resistance values for
different board configurations.
Figure 17. Instantaneous Temperature Rise of an 8.0 W
0.0
10.0
20.0
30.0
40.0
50.0
60.0
0
100
200
300
400
Time (millisec)
Time (ms)
Table 5. Thermal Resistance Data
Type
Condition
Symbol Value  Unit
Junction to Ambient
Single-layer board (1s), per JEDEC JESD51-2 with board (JESD51-3) horizontal
R
?/DIV>
JA
103   癈/W
Junction to Ambient
Four-layer board (2s2p), per JEDEC JESD51-2 with board (JESD51-3) horizontal
R
?/DIV>
JMA
65   癈/W
Junction to Ambient
Single-layer board with a 300 mm
2
radiator pad on its top surface, not standard JEDEC
    69   癈/W
Junction to Ambient
Single-layer board with a 600 mm
2
radiator pad on its top surface, not standard JEDEC
    65   癈/W
Junction to Ambient
Four-layer board with a via for each thermal lead, not standard JEDEC
    51   癈/W
Junction to Ambient
Four-layer board with a 300 mm
2
radiator pad on its top surface and a full array of vias
between radiator pad and top surface, not standard JEDEC
    47   癈/W
Junction to Ambient
Four-layer board with a 600 mm
2
radiator pad on its top surface and a full array of vias
between radiator pad and top surface, not standard JEDEC
    47   癈/W
Junction to Board
Thermal resistance between die and board per JEDEC JESD51-8
R
?/DIV>
JB
29   癈/W
Junction to Case
Thermal resistance between die and case top
R
?/DIV>
JC
33   癈/W
Junction to Package
Top
Temperature difference between package top and junction per JEDEC JESD51-2
?/DIV>
JT
12   癈/W
Junction to Lead
Thermal resistance between junction and thermal lead, not standard JEDEC
R
?/DIV>
JL
33   癈/W
相關代理商/技術參數 |
參數描述 |
MCZ34652EFR2SCALE |
制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:2.0 A Negative Voltage Hot Swap Controller with Enhanced Programmability |
MCZ34653EF |
功能描述:熱插拔功率分布 Hot Swap Controller 1.0 Neg Vltg RoHS:否 制造商:Texas Instruments 產品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
MCZ34653EF/R2 |
制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:1.0 A Negative Voltage Hot Swap Controller |
MCZ34653EFR2 |
功能描述:熱插拔功率分布 Hot Swap Controller 1.0 Neg Vltg RoHS:否 制造商:Texas Instruments 產品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
MCZ34670EG |
功能描述:熱插拔功率分布 POWER OVER ETHERNET RoHS:否 制造商:Texas Instruments 產品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
主站蜘蛛池模板:
卢龙县|
安徽省|
阳东县|
弋阳县|
墨玉县|
故城县|
抚远县|
乌拉特中旗|
江孜县|
玉溪市|
广州市|
汝南县|
梨树县|
尖扎县|
鄢陵县|
镶黄旗|
资阳市|
淮南市|
宜城市|
连山|
宝应县|
玉溪市|
永平县|
德惠市|
嘉兴市|
那坡县|
蓬溪县|
古浪县|
吴忠市|
鄂托克前旗|
吉隆县|
平乐县|
靖西县|
宣城市|
民和|
瓮安县|
梅州市|
通榆县|
蒙自县|
疏勒县|
虹口区|