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| 型号： | LTC4253AIGN#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | -48V Hot Swap Controller with Sequencer; Package: SSOP; No of Pins: 16; Temperature Range: -40°C to +85°C |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| 封装： | 0.150 INCH, LEAD FREE, PLASTIC, SSOP-16 |
| 文件页数： | 14/34页 |
| 文件大小： | 369K |
| 代理商： | LTC4253AIGN#PBF |
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LTC4253/LTC4253A
21
425353afd
Computingthemaximumsoft-startcapacitorvalueduring
soft-start to a load short is complicated by the nonlinear
MOSFET’s SOA characteristics and the RSSCSS response.
An overconservative but simple approach begins with the
maximum circuit breaker current, given by:
ICB(MAX) =
VCB(MAX)
RS
(14)
where VCB(MAX) is 60mV (55mV for the LTC4253A).
From the SOA curves of a prospective MOSFET, determine
the time allowed, tSOA(MAX). CSS is given by:
CSS =
tSOA(MAX)
0.916 RSS
for the LTC4253
CSS =
tSOA(MAX)
2.48 RSS
for the LTC4253A
(15)
In the above example, 60mV/40mΩ gives 1.5A. tSOA for
the IRF530S is 40ms. From Equation (15), CSS = 437nF.
Actual board evaluation showed that CSS = 100nF was ap-
propriate. The ratio ( RSS CSS ) to tCL(CHARGE) is a good
gauge as large ratios may result in the time-out period
expiringprematurely.Thisgaugeisdeterminedempirically
with board level evaluation.
SUMMARY OF DESIGN FLOW
To summarize the design flow, consider the application
shown in Figure 3 for the LTC4253A. It was designed for
80W and CL=100F.
Calculate maximum load current: 80W/43V = 1.86A;
allowing for 83% converter efficiency, IIN(MAX) = 2.2A.
Calculate RS: from Equation (8) RS = 20mΩ.
Calculate ISHORT-CIRCUIT(MAX): from Equation (10)
ISHORTCIRCUIT(MAX) = 3.3A.
Select a MOSFET that can handle 3.3A at 71V: IRF530S.
Calculate CT: from Equation (13) CT = 302nF. Select
CT = 680nF, which gives the circuit breaker time-out
period tMAX = 5.9ms.
ConsultMOSFETSOAcurves:theIRF530Scanhandle3.3A
at 100V for 8.3ms, so it is safe to use in this application.
Calculate CSS: using Equations (14) and (15) select
CSS=33nF.
FREQUENCY COMPENSATION
The LTC4253 typical frequency compensation network
for the analog current limit loop is a series RC (10Ω)
and CC connected from GATE to VEE. Figure 6 depicts the
relationship between the compensation capacitor CC and
the MOSFET’s CISS. The line in Figure 6 is used to select
a starting value for CC based upon the MOSFET’s CISS
specification. Optimized values for CC are shown for sev-
eral popular MOSFETs. Differences in the optimized value
of CC versus the starting value are small. Nevertheless,
compensation values should be verified by board level
short-circuit testing.
As seen in Figure 5, at the onset of a short-circuit event,
theinputsupplyvoltagecanringdramaticallyduetoseries
inductance.IfthisvoltageavalanchestheMOSFET,current
continues to flow through the MOSFET to the output. The
analog current limit loop cannot control this current flow
and therefore the loop undershoots. This effect cannot be
eliminated by frequency compensation. A Zener diode is
required to clamp the input supply voltage and prevent
MOSFET avalanche.
Figure 6. Recommended Compensation
Capacitor CC vs MOSFET CISS for the LTC4253
MOSFET CISS (pF)
COMPENSATION
CAPACITOR
C
C(nF)
4253 F06
60
50
40
30
20
10
0
2000
4000
6000
8000
IRF530
IRF540
IRF740
IRF3710
NTY100N10
applicaTions inForMaTion
相关PDF资料 |
PDF描述 |
|---|---|
| LTC4253AIGN#TRPBF | -48V Hot Swap Controller with Sequencer; Package: SSOP; No of Pins: 16; Temperature Range: -40°C to +85°C |
| LTC4253CGN#PBF | -48V Hot Swap Controller with Sequencer; Package: SSOP; No of Pins: 16; Temperature Range: 0°C to +70°C |
| LTC4253CGN#TRPBF | -48V Hot Swap Controller with Sequencer; Package: SSOP; No of Pins: 16; Temperature Range: 0°C to +70°C |
| LTC4253IGN#PBF | -48V Hot Swap Controller with Sequencer; Package: SSOP; No of Pins: 16; Temperature Range: -40°C to +85°C |
| LTC4253IGN#TRPBF | -48V Hot Swap Controller with Sequencer; Package: SSOP; No of Pins: 16; Temperature Range: -40°C to +85°C |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4253BCGN#PBF | 功能描述:IC HOT SWAP CONTROLLER 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LTC4253BCGN#PBF | 制造商:Linear Technology 功能描述:HOT SWAP CONTROLLER -48V SSOP-16 |
| LTC4253BCGN#TRPBF | 功能描述:IC HOT SWAP CONTROLLER 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4253BIGN#PBF | 功能描述:IC HOT SWAP CONTROLLER 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LTC4253BIGN#PBF | 制造商:Linear Technology 功能描述:HOT SWAP CONTROLLER -48V SSOP-16 |
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