Electronic Components Datasheet Search |
|
PT5825 Datasheet(PDF) 5 Page - Texas Instruments |
|
PT5825 Datasheet(HTML) 5 Page - Texas Instruments |
5 / 10 page Application Notes For technical support and more information, see inside back cover or visit www.ti.com PT5820 Series Operating Features of the PT5820 Series of Step-Down Integrated Switching Regulators Under-Voltage Lockout (UVLO) The PT5820 series of non-isolated step-down ISRs incorporate an under-voltage lockout (UVLO) function. The UVLO provides a clean transition during power-up and power-down, allowing the regulator to tolerate a slowly rising input voltage. The UVLO prevents opera- tion of the regulator until the input voltage is at or above above the UVLO threshold. The UVLO threshold is just below the minimum input voltage. Until the input voltage is above this threshold, the status of the Inhibit control (pin 2) is overriden, and the module will not produce an output. When the minimum input voltage of 10.8V is applied, the output status is determined by the Inhibit control. If the Inhibit pin is open-circuit (not grounded), the module will automatically power up. (Note: Even though the applied input voltage may be above the UVLO threshold, operation to the published specifications requires that the input voltage be at or above the minimum specified. Operation of the module below the minimum input voltage is not recommended). Soft-Start Power Up Following either the application of a valid input source voltage, or the removal of a ground signal to the Inhibit control pin (with input power applied), the regulator will initiate a soft-start power up. The soft start slows the rate at which the output voltage rises, and also introduces a short time delay, td (approx. 10–15ms). Figure 1-1 shows the power-up characteristic of a PT5821 (3.3V). The delay time, td, is measured from the point at which the input voltage rises above the UVLO threshold to when the output voltage starts to rise. During this period the output of the regulator will assert a low impedance to ground. This has the effect of discharging any residual voltage across the output capacitors, and will crowbar any voltage supplied from external sources. Figure 1-1; Soft-Start Power Up Over-Current Protection To protect against load faults, the PT5820 series incor- porates output over-current protection. Applying a load that exceeds the regulator’s over-current threshold (see data sheet specifications) will cause the regulated output to shut down. Following shutdown the ISR will periodi- cally attempt to recover by initiating a soft-start power-up. This is often described as a “hiccup” mode of operation, whereby the module continues in the cycle of successive shutdown and power up until the load fault is removed. During this period, the average current flowing into the fault is significantly reduced. Once the fault is removed, the converter automatically recovers and returns to normal operation. Thermal Shutdown The PT5820 series ISRs incorporate thermal shutdown, which protects the module’s internal circuitry against excessively high temperatures. A rise in the temperature of the internal components may be the result of a drop in airflow, or a high ambient temperature. If the module’s internal temperature exceeds the shutdown threshold (see data sheet specifications), the regulator output is disabled and the output voltage is reduced to zero. The recovery is automatic, and begins with a soft-start power up. It occurs when the the sensed temperature decreases by about 10°C below the trip point. Note: The over-temperature protection is a last resort mecha- nism to prevent thermal stress to the regulator. Operation at or close to the thermal shutdown temperature is not recom- mended and will reduce the long-term reliability of the module. Always operate the regulator within the specified Safe Operating Area (SOA) limits for the worst-case conditions of ambient temperature and airflow. Output Voltage Adjustment The PT5820 series ISRs offer OEMs two alternative methods of output voltage adjustment. The Margin Up and Margin Down control inputs provide a convenient method of adjusting the output voltage by a nominal ±5% of the factory setpoint voltage. For a more perma- nent and precise method of adjustment, the Vo Adjust control allows the output to be adjusted in any incre- ment by up to ±10%. For more information on this subject, consult the related application note on output voltage adjustment. Vo (2V/Div) Vin (5V/Div) HORIZ SCALE: 5ms/Div td |
Similar Part No. - PT5825 |
|
Similar Description - PT5825 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |