参数资料
| 型号： | MAX5943BEEE+ |
| 厂商： | Maxim Integrated |
| 文件页数： | 15/20页 |
| 文件大小： | 0K |
| 描述： | IC FIREWIRE CURR LIMITER 16-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 100 |
| 应用： | FireWire? 应用程序 |
| FET 型： | N 沟道 |
| 输出数： | 2 |
| 内部开关： | 无 |
| 延迟时间 - 关闭： | 100ns |
| 电源电压： | 7.5 V ~ 37 V |
| 电流 - 电源： | 1.3mA |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-QSOP |
| 包装： | 管件 |
FireWire Current Limiter and Low-Drop
ORing Switch Controller
Fault Management
The MAX5943 offers either latch or autoretry fault man-
To prevent the MAX5943B–MAX5943E from starting up
in a fault condition set:
agement configurable by the LATCH input. Connect
LATCH to IN for latch fault management or connect
LATCH to GND for autoretry fault management. In latch
fault management, FAULT latches low, GATE1 and
I INRUSH <
V TH
R SENSE
GATE2 latch off indefinitely. Cycle ON low and then
high to unlatch and restart the MAX5943. However, the
MAX5943 will not enter a startup cycle until t OFF has
+
R SENSE
Q1
Q2
1k Ω
C GATE
I C
I LOAD
expired. Figure 9 illustrates a way to reset the MAX5943
after a fault using a pushbutton switch.
45 μ A
In autoretry fault management, the MAX5943_ attempt
to restart after a t OFF of 128 x t ILIM (or 128 x t CB ) limit-
V IN
IN
SENSE GATE1 GATE2
MAX5943B–MAX5943E
OUT
C OUT LOAD
ing the duty cycle of the MOSFETs to 1/129 under con-
tinuous fault conditions. FAULT deasserts every time a
restart attempt is made.
-
GND
Applications Information
Startup Consideration
MAX5943A
During startup, a large capacitor at OUT may result in a
charging current equivalent to the current limit. Choose a
current-limit timeout that will allow a successful startup.
The timeout can be approximated using the following
Figure 10. Controlling the MAX5943B–MAX5943E Inrush Current
Optimizing for Short-Circuit Conditions
Choosing R SENSE
Select a sense resistor that causes the circuit-breaker
voltage drop at a current-limit/circuit-breaker level
above the maximum normal operating current.
Typically, set the overload current at 1.2 to 1.5 times
equation:
t ILIM >
C OUT × V IN
I LIMIT ? I LOAD
the full load current.
Choose the sense-resistor power rating to accommodate
an overcurrent condition:
\where I LIMIT is the programmed current limit, C OUT is
the capacitor at OUT, V IN is the supply voltage, and
I LOAD is the load current during startup. With IN = 12V,
C OUT = 330μF, I LIMIT = 1.5A, and I LOAD = 0, the
MAX5943 commences by charging the output capacitor
with 1.5A for approximately 2.7ms. Therefore, the
MAX5943A current-limit timeout period (t ILIM ) should be
greater than 2.7ms for a successful startup. Otherwise,
the MAX5943A powers up in fault management mode
by exceeding the current-limit timeout period.
MAX5943B–MAX5943E
The MAX5943B–MAX5943E do not control the inrush
current during startup. Inrush current control can be
P RSENSE = I 2 LIMIT x R SENSE
where P RSENSE is the power dissipated across R SENSE
during a current-limit/circuit-breaker fault.
Under short-circuit conditions, it is imperative that the
appropriate sense resistor is utilized. Operating the
MAX5943B –MAX5943E at high input voltages can
cause very large currents during the circuit-breaker
timeout period. The peak current will be limited by the
saturation current of Q2 or the series resistance in the
power path (R TOTAL ).
Using a 30m Ω on-resistance MOSFET at GATE1 and
GATE2 and a 30m Ω sense resistor results in a short-cir-
cuit current approximately equal to:
implemented by placing a resistor and capacitor at
GATE2 (Figure 10) to slowly ramp up the gate voltage,
thus limiting the inrush current. The inrush current can
be approximated using the following formula:
where:
I SC = V IN /R TOTAL
R TOTAL = R SENSE + 2 x (R ON )
I INRUSH =
C OUT
C GATE 2
× I G 2 U + I LOAD
= 30m Ω + 2 x (30m Ω ) = 90m Ω
For example, an input voltage of 20V produces a current
at approximately 222A (or I SAT of Q2, whichever is less)
Where I G2U is GATE2 ’s 45μA sourcing current and
I LOAD is the load current at startup.
in the power path for the circuit-breaker timeout period.
Choose an R SENSE capable of handling the high power
dissipation during a short-circuit event.
______________________________________________________________________________________
15
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX5943BEEE+ | 功能描述:热插拔功率分布 FireWire Current Limiter 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 |
| MAX5943BEEE+T | 功能描述:热插拔功率分布 FireWire Current Limiter 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 |
| MAX5943BEEE-T | 功能描述:热插拔功率分布 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 |
| MAX5943CEEE | 功能描述:热插拔功率分布 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 |
| MAX5943CEEE+ | 功能描述:热插拔功率分布 FireWire Current Limiter 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 |
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