参数资料
型号: TPS2392PW
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: 13/33页
文件大小: 596K
代理商: TPS2392PW
TPS2392
TPS2393
SLUS536C AUGUST 2002 REVISED AUGUST 2004
www.ti.com
20
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 TPS2392 or TPS2393, 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 ia 2 A
(40 mV/20 m
).
setting the inrush slew rate
The TPS2392/93 devices enable 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 TPS2392 and TPS2393 initiate 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)
相关PDF资料
PDF描述
TPS2393PWR 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO14
TPS2393PWRG4 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO14
TPS2400DBVT 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5
TPS2400DBVR 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5
TPS2410PWG4 SPECIALTY ANALOG CIRCUIT, PDSO14
相关代理商/技术参数
参数描述
TPS2392PWG4 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
TPS2392PWR 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
TPS2392PWRG4 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
TPS2393APW 功能描述:热插拔功率分布 48V Hot Swap 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
TPS2393APWG4 功能描述:热插拔功率分布 -48V Hot Swap 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