Zakładka z wyszukiwarką danych komponentów |
|
CS5207A-1 Arkusz danych(PDF) 6 Page - ON Semiconductor |
|
CS5207A-1 Arkusz danych(HTML) 6 Page - ON Semiconductor |
6 / 8 page CS5207A−1 http://onsemi.com 6 STABILITY CONSIDERATIONS The output compensation capacitor helps determine three main characteristics of a linear regulator: start−up delay, load transient response, and loop stability. The capacitor value and type is based on cost, availability, size and temperature constraints. A tantalum or aluminum electrolytic capacitor is best, since a film or ceramic capacitor with almost zero ESR can cause instability. The aluminum electrolytic capacitor is the least expensive solution. However, when the circuit operates at low temperatures, both the value and ESR of the capacitor will vary considerably. The capacitor manufacturer’s data sheet provides this information. A 300 μF tantalum capacitor will work for most applications, but with high current regulators such as the CS5207A−1 the transient response and stability improve with higher values of capacitance. The majority of applications for this regulator involve large changes in load current so the output capacitor must supply the instantaneous load current. The ESR of the output capacitor causes an immediate drop in output voltage given by: DV + DI ESR For microprocessor applications it is customary to use an output capacitor network consisting of several tantalum and ceramic capacitors in parallel. This reduces the overall ESR and reduces the instantaneous output voltage drop under transient load conditions. The output capacitor network should be as close to the load as possible for the best results. Protection Diodes When large external capacitors are used with a linear regulator it is sometimes necessary to add protection diodes. If the input voltage of the regulator gets shorted, the output capacitor will discharge into the output of the regulator. The discharge current depends on the value of the capacitor, the output voltage and the rate at which VIN drops. In the CS5207A−1 regulator, the discharge path is through a large junction and protection diodes are not usually needed. If the regulator is used with large values of output capacitance and the input voltage is instantaneously shorted to ground, damage can occur. In this case, a diode connected as shown in Figure 13 is recommended. A rule of thumb useful in determining if a protection diode is required is to solve for current I + C V T where: I is the current flow out of the load capacitance when VIN is shorted, C is the value of the load capacitance, V is the output voltage, and T is the time duaration required for VIN to transition from high to being shorted. If the calculated current is greater than or equal to the typical short circuit current value provided in the specifications, serious thought should be given to including a protection diode. Figure 13. VIN CS5207A−1 VOUT Adj Current Limit The internal current limit circuit limits the output current under excessive load conditions and protects the regulator. Short Circuit Protection The device includes foldback short circuit current limit that clamps the output current at approximately two amperes less than its current limit value. Thermal Shutdown The thermal shutdown circuitry is guaranteed by design to become activated above a die junction temperature of 150°C and to shut down the regulator output. This circuitry includes a thermal hysteresis circuit with 25°C of typical hysteresis, thereby allowing the regulator to recover from a thermal fault automatically. Calculating Power Dissipation and Heat Sink Requirements High power regulators such as the CS5207A−1 usually operate at high junction temperatures. Therefore, it is important to calculate the power dissipation and junction temperatures accurately to ensure that an adequate heat sink is used. Since the package tab is connected to VOUT on the CS5207A−1, electrical isolation may be required for some applications. Also, as with all high power packages, thermal compound is necessary to ensure proper heat flow. For added safety, this high current LDO includes an internal thermal shutdown circuit The thermal characteristics of an IC depend on the following four factors. Junction temperature, ambient temperature, die power dissipation, and the thermal resistance from the die junction to ambient air. The maximum junction temperature can be determined by: TJ(max) + TA(max) ) PD(max) RQJA |
Podobny numer części - CS5207A-1 |
|
Podobny opis - CS5207A-1 |
|
|
Link URL |
Polityka prywatności |
ALLDATASHEET.PL |
Czy Alldatasheet okazała się pomocna? [ DONATE ] |
O Alldatasheet | Reklama | Kontakt | Polityka prywatności | Linki | Lista producentów 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 |