 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
CS8156 Datasheet(PDF) 7 Page - Cherry Semiconductor Corporation |
|
||||||||||||||||||||||||||||||
CS8156 Datasheet(HTML) 7 Page - Cherry Semiconductor Corporation |
|
|
7 / 8 page  7 Application Notes Step 3: Increase the ESR of the capacitor from zero using the decade box and vary the load current until oscillations appear. Record the values of load current and ESR that cause the greatest oscillation. This represents the worst case load conditions for the output at low temperature. Step 4: Maintain the worst case load conditions set in step 3 and vary the input voltage until the oscillations increase. This point represents the worst case input voltage conditions. Step 5: If the capacitor is adequate, repeat steps 3 and 4 with the next smaller valued capacitor. A smaller capaci- tor will usually cost less and occupy less board space. If the output oscillates within the range of expected operat- ing conditions, repeat steps 3 and 4 with the next larger standard capacitor value. Step 6: Test the load transient response by switching in various loads at several frequencies to simulate its real working environment. Vary the ESR to reduce ringing. Step 7: Remove the unit from the environmental chamber and heat the IC with a heat gun. Vary the load current as instructed in step 5 to test for any oscillations. Once the minimum capacitor value with the maximum ESR is found for each output, a safety factor should be added to allow for the tolerance of the capacitor and any variations in regulator performance. Most good quality aluminum electrolytic capacitors have a tolerance of +/- 20% so the minimum value found should be increased by at least 50% to allow for this tolerance plus the variation which will occur at low temperatures. The ESR of the capacitors should be less than 50% of the maximum allow- able ESR found in step 3 above. Repeat steps 1 through 7 with C3, the capacitor on the other output. The maximum power dissipation for a dual output regula- tor (Figure 1) is: PD(max) = {VIN(max)ÐVOUT1(min)}IOUT1(max)+ {VIN(max)ÐVOUT2(min)}IOUT2(max)+VIN(max)IQ (1) Where: VIN(max) is the maximum input voltage, VOUT1(min) is the minimum output voltage from VOUT1, VOUT2(min) is the minimum output voltage fromVOUT2, IOUT1(max) is the maximum output current for the appli- cation, IOUT2(max) is the maximum output current for the appli- cation, and IQ is the quiescent current the regulator consumes at IOUT(max). Once the value of PD(max) is known, the maximum permis- sible value of RQJA can be calculated: RQJA = (2) Figure 1: Dual output regulator with key performance parameters labeled. The value of RQJA can then be compared with those in the package section of the data sheet. Those packages with RQJA's less than the calculated value in equation 2 will keep the die temperature below 150¡C. In some cases, none of the packages will be sufficient to dissipate the heat generated by the IC, and an external heatsink will be required. A heat sink effectively increases the surface area of the package to improve the flow of heat away from the IC and into the surrounding air. Each material in the heat flow path between the IC and the outside environment will have a thermal resistance. Like series electrical resistances, these resistances are summed to determine the value of RQJA: RQJA = RQJC + RQCS + RQSA (3) where RQJC = the junctionÐtoÐcase thermal resistance, RQCS = the caseÐtoÐheatsink thermal resistance, and RQSA = the heatsinkÐtoÐambient thermal resistance. RQJC appears in the package section of the data sheet. Like RQJA, it too is a function of package type. RQCS and RQSA are functions of the package type, heatsink and the inter- face between them. These values appear in heat sink data sheets of heat sink manufacturers. C1* 0.1 mF + C2** 22 mF + C3** 22 mF VIN ENABLE VOUT1 VOUT2 Gnd CS8156 Test & Application Circuit Heat Sinks VIN Smart Regulator VOUT1 IOUT1 IIN IQ Control Features } VOUT2 IOUT2 150¡C - T A PD Calculating Power Dissipation in a Dual Output Linear Regulator NOTES: *C1 required if regulator is located far from power supply filter. ** C2, C3 required for stability. |
Similar Part No. - CS8156 |
|
Similar Description - CS8156 |
|
|
|
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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
