Electronic Components Datasheet Search |
|
SC1458BEVB Datasheet(PDF) 10 Page - Semtech Corporation |
|
SC1458BEVB Datasheet(HTML) 10 Page - Semtech Corporation |
10 / 13 page SC1458 10 Applications Information (continued) until the fault is removed and the load current returns to a specified level. Component Selection A capacitance of 1μF or larger on each output is recommended to ensure stability. Ceramic capacitors of type X5R or X7R should be used because of their low ESR and stable temperature coefficients. It is also recommended that the input be bypassed with a 2.2μF, low ESR X5R or X7R capacitor to minimize noise and improve transient response. Note: Tantalum and Y5V capacitors are not recommended. A bypass capacitor (minimum of 22nF) should be connected between the BYP and GND pins to meet all noise-sensitive requirements. Increasing the capacitance to 100nF will further improve PSRR and output noise (SC1458B only). Thermal Considerations Although each of the two LDOs in the SC1458 can provide 300mA of output current, the maximum power dissipation in the device is restricted by the miniature package size. The graphs in Figure 2 and Figure 3 can be used as a guideline to determine whether the input voltage, output voltages, output currents, and ambient temperature of the system result in power dissipation within the operating limits or if further thermal relief is required. 0 0.1 0.2 0.3 0.4 0.5 0.6 3 3.5 4 4.5 5 5.5 6 Input Voltage (V) ______ TA=+25°C, PD(MAX)= 1.9W - - - - TA=+85°C, PD(MAX)= 1.0W Figure 2 — Safe Operating Limit 0 0.3 0.6 0.9 1.2 1.5 1.8 -40 -20 0 20 40 60 80 100 Ambient Temperature ( oC) TJ(Max)=150°C TJ(Max)=125°C Figure 3 — Maximum P D vs. TA The following procedure can be followed to determine if the thermal design of the system is adequate.The junction temperature of the SC1458 can be determined in known operating conditions using the following equation: T J = T A +(P D x θ JA ) where T J = Junction Temperature (°C) T A = Ambient Temperature (°C) P D = Power Dissipation (W) θ JA = Thermal Resistance Junction to Ambient (°C/W) Example An SC1458A is used to provide outputs of 2.5V, 150mA from LDOA and 1.8V, 200mA from LDOB. The input voltage is 4.2V, and the ambient temperature of the system is 60°C. P D = 0.15(4.2 – 2.5) + 0.2(4.2 – 1.8) = 0.74W and T J = 60 + (0.74 x 50) = 97°C Figure 3 shows that the power dissipation is within limits at T A = 60°C and calculation of T J shows that it is within the specified limit of 150°C. This means that operation of the SC1458 under these conditions is within the specified limits and the device would not require further thermal relief measures. |
Similar Part No. - SC1458BEVB |
|
Similar Description - SC1458BEVB |
|
|
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 |