Motore di ricerca datesheet componenti elettronici |
|
CS5156GN16 Scheda tecnica(PDF) 11 Page - Cherry Semiconductor Corporation |
|
CS5156GN16 Scheda tecnica(HTML) 11 Page - Cherry Semiconductor Corporation |
11 / 14 page Applications Information: continued 11 Figure 15: CS5156 gate drive waveforms depicting rail to rail swing. The most important aspect of MOSFET performance is RDSON, which effects regulator efficiency and MOSFET thermal management requirements. The power dissipated by the MOSFETs and the Schottky diode may be estimated as follows; Switching MOSFET: Power = ILOAD2 × RDSON × duty cycle Schottky diode: Power = VFORWARD × ILOAD × (1 - duty cycle) Duty Cycle = Off Time Capacitor (COFF) The COFF timing capacitor sets the regulator off time: TOFF = COFF × 4848.5 When the VFFB pin is less than 1V, the current charging the COFF capacitor is reduced. The extended off time can be cal- culated as follows: TOFF = COFF × 24,242.5. Off time will be determined by either the TOFF time, or the time out timer, whichever is longer. The preceding equations for duty cycle can also be used to calculate the regulator switching frequency and select the COFF timing capacitor: COFF = , where: Period = “Droop” Resistor for Adaptive Voltage Positioning Adaptive voltage positioning is used to reduce output volt- age excursions during abrupt changes in load current. Regulator output voltage is offset +40mV when the regula- tor is unloaded, and -40mV at full load. This results in increased margin before encountering minimum and maxi- mum transient voltage limits, allowing use of less capaci- tance on the regulator output (see Figure 7). To implement adaptive voltage positioning, a “droop” resistor must be connected between the output inductor and output capacitors and load. This is normally imple- mented by a PC board trace of the following value: RDROOP = Adaptive voltage positioning can be disabled for improved DC regulation by connecting the VFB pin directly to the load using a separate, non-load current carrying circuit trace. Input and Output Capacitors These components must be selected and placed carefully to yield optimal results. Capacitors should be chosen to pro- vide acceptable ripple on the input supply lines and regula- tor output voltage. Key specifications for input capacitors are their ripple rating, while ESR is important for output capacitors. For best transient response, a combination of low value/high frequency and bulk capacitors placed close to the load will be required. Output Inductor The inductor should be selected based on its inductance, current capability, and DC resistance. Increasing the induc- tor value will decrease output voltage ripple, but degrade transient response. Thermal Considerations for Power MOSFETs and Diodes In order to maintain good reliability, the junction tempera- ture of the semiconductor components should be kept to a maximum of 150°C or lower. The thermal impedance (junc- tion to ambient) required to meet this requirement can be calculated as follows: Thermal Impedance = A heatsink may be added to TO-220 components to reduce their thermal impedance. A number of PC board layout techniques such as thermal vias and additional copper foil TJUNCTION(MAX) - TAMBIENT Power Thermal Management 80mV IMAX 1 switching frequency Period × (1 - duty cycle) 4848.5 VOUT + VFORWARD VIN + VFORWARD - (ILOAD × RDSON OF SWITCH FET) Channel 3 = VGATE M1= VGATE - 5VIN Channel 2 = Inductor Switching Node |
Codice articolo simile - CS5156GN16 |
|
Descrizione simile - CS5156GN16 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEETIT.COM |
Lei ha avuto il aiuto da alldatasheet? [ DONATE ] |
Di alldatasheet | Richest di pubblicita | contatti | Privacy Policy | scambio Link | Ricerca produttore 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 |