Electronic Components Datasheet Search |
|
TPS54373PWP Datasheet(PDF) 9 Page - Texas Instruments |
|
|
TPS54373PWP Datasheet(HTML) 9 Page - Texas Instruments |
9 / 16 page TPS54373 SLVS455A − JANUARY 2003 − REVISED JUNE 2003 www.ti.com 9 OPERATING FREQUENCY In the application circuit, the RT pin is grounded through a 71.5-k Ω resistor (R6) to select the operating frequency of 700 kHz. To set a different frequency, place a 68-k Ω to 180-k Ω resistor between RT (pin 28) and analog ground or leave RT floating to select the default of 350 kHz. The resistance can be approximated using the following equation: R + 500 kHz Switching Frequency 100 [k W] OUTPUT FILTER The output filter is composed of a 0.65- µH inductor (L1) and 3 x 22- µF capacitors (C5, C7 and C8). The inductor is a low dc resistance (0.010 Ω) type, Vishay IHLP-2525CZ-01 1.0 µH. The capacitors used are 22-µF, 6.3-V ceramic types with X5R dielectric. An additional high frequency bypass capacitor, C13 is also used. PRECHARGE CIRCUIT VIN precharges the output of the application circuit through series diodes (D1 and D2) during start-up. As the input voltage increases at start-up, the output is precharged to VIN minus the forward bias voltage of the two diodes. When the internal reference has ramped up to a value greater than the voltage fed back to the VSENSE pin, the output of the internal error amplifier begins to increase. When this output reaches the maximum ramp amplitude, the output of the PWM comparator reaches 100 percent duty cycle and the internal logic enables the high-side FET driver and switching begins. The output tracks the internal reference until the preset output voltage is reached. Under no circumstances should the precharge voltage be allowed to increase above the preset output value. GROUNDING AND POWERPAD LAYOUT The TPS54373 has two internal grounds (analog and power). Inside the TPS54373, the analog ground ties to all of the noise sensitive signals, while the power ground ties to the noisier power signals. The PowerPAD must be tied directly to AGND. Noise injected between the two grounds can degrade the performance of the TPS54373, particularly at higher output currents. However, ground noise on an analog ground plane can also cause problems with some of the control and bias signals. For these reasons, separate analog and power ground areas are recommended. The analog ground area should be tied to the power ground area directly at the IC to reduce noise between the two grounds. The only components that should tie directly to the power ground area are the input capacitor, the output capacitor, the input voltage decoupling capacitor, and the PGND pins of the TPS54373. The power ground areas as well as the PowerPAD mounting area should be tied to any internal ground planes using multiple vias. The layout of the TPS54373 evaluation module is representative of a recommended layout for a 2-layer board. Documentation for the TPS54373 evaluation module can be found on the Texas Instruments web site under the TPS54373 product folder. LAYOUT CONSIDERATIONS FOR THERMAL PERFORMANCE For operation at full rated load current, the analog ground plane must provide adequate heat dissipating area. A 3 inch by 3 inch plane of 1 ounce copper is recommended, though not mandatory, depending on ambient temperature and airflow. Most applications have larger areas of internal ground plane available, and the PowerPAD should be connected to the largest area available. Additional areas on the top or bottom layers also help dissipate heat, and any area available should be used when 3 A or greater operation is desired. Connection from the exposed area of the PowerPAD to the analog ground plane layer should be made using 0.013 inch diameter vias to avoid solder wicking through the vias. Six vias should be in the PowerPAD area with four additional vias located under the device package. The size of the vias under the package, but not in the exposed thermal pad area, can be increased to 0.018. Additional vias beyond the ten recommended that enhance thermal performance should be included in areas not under the device package. (1) |
Similar Part No. - TPS54373PWP |
|
Similar Description - TPS54373PWP |
|
|
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 |