ZHCSHR1A September 2017 – February 2018 TPS7A54-Q1
PRODUCTION DATA.
- 1 特性
- 2 應(yīng)用
- 3 說明
- 4 修訂歷史記錄
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Detailed Description
-
8 Application and Implementation
- 8.1
Application Information
- 8.1.1 Recommended Capacitor Types
- 8.1.2 Soft Start and Inrush Current
- 8.1.3 Optimizing Noise and PSRR
- 8.1.4 Charge Pump Noise
- 8.1.5 Current Sharing
- 8.1.6 Adjustable Operation
- 8.1.7 Power-Good Operation
- 8.1.8 Undervoltage Lockout (UVLO) Operation
- 8.1.9 Dropout Voltage (VDO)
- 8.1.10 Device Behavior During Transition From Dropout Into Regulation
- 8.1.11 Load Transient Response
- 8.1.12 Reverse Current Protection Considerations
- 8.1.13 Power Dissipation (PD)
- 8.1.14 Estimating Junction Temperature
- 8.2 Typical Application
- 8.1
Application Information
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文檔支持
- 12機(jī)械、封裝和可訂購信息
封裝選項(xiàng)
機(jī)械數(shù)據(jù) (封裝 | 引腳)
- RGR|20
散熱焊盤機(jī)械數(shù)據(jù) (封裝 | 引腳)
- RGR|20
訂購信息
8.1.2 Soft Start and Inrush Current
Soft start refers to the ramp-up characteristic of the output voltage during LDO turnon after EN and UVLO achieve threshold voltage. The noise-reduction capacitor serves a dual purpose of both governing output noise reduction and programming the soft-start ramp during turnon.
Inrush current is defined as the current into the LDO at the IN pin during start-up. Inrush current then consists primarily of the sum of load current and the current used to charge the output capacitor. This current is difficult to measure because the input capacitor must be removed, which is not recommended. However, Equation 3 can estimate this soft-start current:
where
- VOUT(t) is the instantaneous output voltage of the turnon ramp
- dVOUT(t) / dt is the slope of the VOUT ramp
- RLOAD is the resistive load impedance