参数资料
型号: TPS70845PWP
厂商: Texas Instruments, Inc.
元件分类: 线性稳压
英文描述: DUAL-OUTPUT LOW-DROPOUT VOLTAGE REGULATORS WITH INTEGRATED SVS FOR SPLIT VOLTAGE SYSTEMS
中文描述: 两用低压差电压带的劈开SVS的系统集成稳压器的输出电压
文件页数: 17/29页
文件大小: 449K
代理商: TPS70845PWP
TPS70845, TPS70848, TPS70851, TPS70858, TPS70802
DUAL-OUTPUT LOW-DROPOUT VOLTAGE REGULATORS
WITH INTEGRATED SVS FOR SPLIT VOLTAGE SYSTEMS
SLVS301B – JUNE 2000 – REVISED OCTOBER 2002
24
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
APPLICATION INFORMATION
Figure 38 shows the output capacitor and its parasitic impedances in a typical LDO output stage.
LDO
VI
VESR
IO
RESR
CO
RLOAD
VO
+
+
Figure 38. LDO Output Stage With Parasitic Resistances ESR
In steady state (dc state condition), the load current is supplied by the LDO (solid arrow) and the voltage across
the capacitor is the same as the output voltage (V(CO) = VO). This means no current is flowing into the CO
branch. If IO suddenly increases (transient condition), the following occurs:
D The LDO is not able to supply the sudden current need due to its response time. Therefore, capacitor CO
provides the current for the new load condition (dashed arrow). CO now acts like a battery with an internal
resistance, ESR. Depending on the current demand at the output, a voltage drop will occur at RESR. This
voltage is shown as VESR in Figure 38.
D When CO is conducting current to the load, initial voltage at the load will be VO = V(CO) – VESR. Due to the
discharge of CO, the output voltage VO will drop continuously until the response time t1 of the LDO is reached
and the LDO will resume supplying the load. From this point, the output voltage starts rising again until it
reaches the regulated voltage. This period is shown as t2 in Figure 39.
The figure also shows the impact of different ESRs on the output voltage. The left brackets show different levels
of ESRs where number 1 displays the lowest and number 3 displays the highest ESR.
From above, the following conclusions can be drawn:
D The higher the ESR, the larger the droop at the beginning of load transient.
D The smaller the output capacitor, the faster the discharge time and the bigger the voltage droop during the
LDO response period.
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TPS70845PWPR 功能描述:低压差稳压器 - LDO Dual-Output LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压(最大值):307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20
TPS70845PWPRG4 功能描述:低压差稳压器 - LDO Dual-Output LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压(最大值):307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20
TPS70848 制造商:TI 制造商全称:Texas Instruments 功能描述:DUAL-OUTPUT LOW-DROPOUT VOLTAGE REGULATORS WITH INTEGRATED SVS FOR SPLIT VOLTAGE SYSTEMS
TPS70848PWP 功能描述:低压差稳压器 - LDO 3.3V/1.2V 250/125mA RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压(最大值):307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20