- 您现在的位置：买卖IC网 > Sheet目录1224 > LM5051MAEVAL/NOPB (National Semiconductor)BOARD EVAL FOR LM5051MA
SNVS702D – OCTOBER 2011 – REVISED MARCH 2013
The dominate MOSFET loss for the LM5051 active OR-ing controller is conduction loss due to source-to-drain
current to the output load, and the R DS(ON) of the MOSFET. This conduction loss could be reduced by using a
MOSFET with the lowest possible R DS(ON) . However, contrary to popular belief, arbitrarily selecting a MOSFET
based solely on having low R DS(ON) may not always give desirable results for several reasons:
1) Reverse transition detection. Higher R DS(ON) will provide increased voltage information to the LM5051 Reverse
Comparator at a lower reverse current level. This will give an earlier MOSFET turn-off condition should the input
voltage become shorted to ground. This will minimize any disturbance of the redundant bus.
2) Reverse current leakage. In cases where multiple input supplies are closely matched it may be possible for
some small current to flow continuously through the MOSFET drain to source (i.e. reverse) without activating the
LM5051 Reverse Comparator. Higher R DS(ON) will reduce this reverse current level.
3) Cost. Generally, as the R DS(ON) rating goes lower, the cost of the MOSFET goes higher.
Selecting a MOSFET with an R DS(ON) that is too large will result in excessive power dissipation.
As a guideline, it is suggest that R DS(ON) be selected to provide at least 20 mV, and no more than 100 mV, at the
nominal load current.
(20 mV / I D ) ≤ R DS(ON) ≤ (100mV / I D )
(10)
The thermal resistance of the MOSFET package should also be considered against the anticipated dissipation in
the MOSFET in order to ensure that the junction temperature (T J ) is reasonably well controlled, since the R DS(ON)
of the MOSFET increases as the junction temperature increases.
P DISS = I D2 x (R DS(ON) )
(11)
Operating with a maximum ambient temperature (T A(MAX) ) of 35°C, a load current of 10A, and an R DS(ON) of 10
m ? , and desiring to keep the junction temperature under 100°C, the maximum junction-to-ambient thermal
resistance rating ( θ JA ) would need to be:
θ JA ≤ (T J(MAX) - T A(MAX) )/(I D2 x R DS(ON) )
θ JA ≤ (100°C - 35°C)/(10A x 10A x 0.01 ? )
θ JA ≤ 65°C/W
(12)
(13)
(14)
16
Product Folder Links: LM5051
Copyright ? 2011–2013, Texas Instruments Incorporated
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
LMR020-0650-CCF9-1KIT2X
KIT DEV LMR020-0650, 120V
LMR040-1000-CCF9-1KIT2X
KIT DEV LMR4 1000 TRUEWHITE
LPSJ601.ZXID
FUSEHOLDER CLASS J 60A IND 1POLE
LR4-1300F
POLYSWITCH PTC RESET 13A STRAP
LR4-170UF
POLYSWITCH PTC RESET 1.7A STRAP
LR4-190SLF
POLYSWITCH PTC RESET 1.9A STRAP
LR4-190XF
POLYSWITCH PTC RESET 1.9A STRAP
LR4-260F
POLYSWITCH PTC RESET 2.6A STRAP
相关代理商/技术参数
LM5051MAX/NOPB
功能描述:热插拔功率分布 Lo Side OR-ing FET Cntlr RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube
LM5056
制造商:TI 制造商全称:Texas Instruments 功能描述:High-Voltage System Power Management Device with PMBusa?￠
LM5056A
制造商:TI 制造商全称:Texas Instruments 功能描述:High-Voltage System Power Management Device with PMBusa?￠
LM5056APMH/NOPB
功能描述:PMIC 解决方案 Hi Vtg System Pwr Mgmt IC
RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel
LM5056APMHE/NOPB
功能描述:PMIC 解决方案 Hi Vtg System Pwr Mgmt IC
RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel
LM5056APMHENOPB
制造商:Texas Instruments 功能描述:LM5056APMHENOPB
LM5056APMHX/NOPB
功能描述:PMIC 解决方案 Hi Vtg System Pwr Mgmt IC
RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel
LM5056APMHXNOPB
制造商:National Semiconductor 功能描述:LM5056APMHXNOPB