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参数资料
| 型号： | TPS2393APWRG4 |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO14 |
| 封装： | GREEN, PLASTIC, TSSOP-14 |
| 文件页数： | 10/30页 |
| 文件大小： | 665K |
| 代理商： | TPS2393APWRG4 |
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TPS2393A
SLUS610 JULY 2004
18
www.ti.com
APPLICATION INFORMATION
Setting the Sense Resistor Value
Due to the currentlimiting action of the internal LCA, the maximum allowable load current for an implementation
is easily programmed by selecting the appropriate sense resistor value. The LCA acts to limit the sense voltage
VI(ISENS) to its internal reference. Once the voltage at the IRAMP pin exceeds approximately 4 V, this limit is
the clamp voltage, VREF_K. Therefore, a maximum sense resistor value can be determined from equation (1).
R
SENSE v
33 mV
IMAX
where:
D RSENSE is the resistor value
D IMAX is the desired current limit
When setting the sense resistor value, it is important to consider two factors, the minimum current that may be
imposed by the TPS2393A, and the maximum load under normal operation of the module. For the first factor,
the specification minimum clamp value is used, as seen in equation (1). This method accounts for the tolerance
in the sourced current limit below the typical level expected (40 mV/RSENSE). (The clamp measurement includes
LCA input offset voltage; therefore, this offset does not have to be factored into the current limit again.) Second,
if the load current varies over a range of values under normal operating conditions, then the maximum load level
must be allowed for by the value of RSENSE. One example of this is when the load is a switching converter, or
brick, which draws higher input current, for a given power output, when the distribution bus is at the low end of
its operating range, with decreasing draw at higher supply voltages. To avoid current-limit operation under
normal loading, some margin should be designed in between this maximum anticipated load and the minimum
current limit level, or IMAX > ILOAD(max), for equation (1).
For example, using a 20-m
sense resistor for a nominal 1-A load application provides a minimum of 650 mA
of overhead for load variance/margin. Typical bulk capacitor charging current during turn-on is 2 A
(40 mV/20 m
).
Setting the Inrush Slew Rate
The TPS2393A enables user-programming of the maximum current slew rate during load start-up events. A
capacitor tied to the IRAMP pin (C1 in the typical application diagram) controls the di/dt rate. Once the sense
resistor value has been established, a value for ramp capacitor CIRAMP, in microfarads, can be determined from
equation (2).
C
IRAMP +
11
100
R
SENSE
di
dt MAX
where:
D RSENSE is the sense resistor value in
D (di/dt)MAX is the desired maximum slew rate in A/s
For example, if the desired slew rate for the typical application shown is 1500 mA/mS, the calculated value for
CIRAMP is about 3700 pF. Selecting the next larger standard value of 3900 pF (as shown in the diagram) provides
some margin for capacitor and sense resistor tolerances.
As described in the Detailed Description section of this datasheet, the TPS2393A initiates ramp capacitor
charging, and consequently, load current di/dt at a reduced rate. This reduced rate applies until the voltage on
the IRAMP pin is about 0.5 V. The maximum di/dt rate, as set by equation (2), is effective once the device has
switched to the 10-
A charging source.
(1)
(2)
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| TPS2393DBTR | 功能描述:热插拔功率分布 Full Featured -48V Industral Temp. 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 |
| TPS2393DBTRG4 | 功能描述:热插拔功率分布 -48V Hot Swap G179 Pwr Mgr Ind Temp 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 |
| TPS2393EVM | 功能描述:电源管理IC开发工具 Simple -48V Hot Swap Contr EVM RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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