전자부품 데이터시트 검색엔진 |
|
CS8161YTHA5 데이터시트(PDF) 7 Page - Cherry Semiconductor Corporation |
|
CS8161YTHA5 데이터시트(HTML) 7 Page - Cherry Semiconductor Corporation |
7 / 8 page 7 Step 1: Place the completed circuit with a tantalum capaci- tor of the recommended value in an environmental cham- ber at the lowest specified operating temperature and monitor the outputs on the oscilloscope. A decade box connected in series with the capacitor C2 will simulate the higher ESR of an aluminum capacitor. (Leave the decade box outside the chamber, the small resistance added by the longer leads is negligible) Step 2: With the input voltage at its maximum value, increase the load current slowly from zero to full load while observing the output for any oscillations. If no oscil- lations are observed, the capacitor is large enough to ensure a stable design under steady state conditions. 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 regulator 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 condi- tions. Step 5: If the capacitor C2 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 capacitor oscillates within the range of expected oper- ating 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 work 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, a safety factor should be added to allow for the tolerance of the capacitor and any variations in regula- tor 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 capacitor should be less than 50% of the maximum allowable ESR found in step 3 above. Once the value for C2 is determined, repeat the steps to determine the appropriate value for C3. The maximum power dissipation for a dual output regula- tor (Figure 1) is PD(max) = {VIN(max)ÐVOUT1(min)}IOUT 1(max)+ {VIN(max)ÐVOUT 2(min)}IOUT2(max)+VIN(max)IQ (1) Where VIN(max) is the maximum input voltage, VOUT 1(min) is the minimum output voltage from VOUT1, VOUT 2(min) is the minimum output voltage from VOUT2, IOUT 1(max) is the maximum output current, for the appli- cation IOUT 2(max) is the maximum output current, for the appli- cation 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 R QJA can be calculated: R QJA = (2) The value of R QJA can then be compared with those in the package section of the data sheet. Those packages with R QJA'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 R QJA. R QJA = RQJC + RQCS + RQSA (3) where R QJC = the junctionÐtoÐcase thermal resistance, R QCS = the caseÐtoÐheatsink thermal resistance, and R QSA = the heatsinkÐtoÐambient thermal resistance. R QJC appears in the package section of the data sheet. Like R QJA, 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. 150¡C - T A PD Application Notes: continued Calculating Power Dissipation in a Dual Output Linear Regulator VIN Smart Regulator VOUT1 IOUT1 IIN IQ Control Features } VOUT2 IOUT2 Figure 1: Dual output regulator with key performance parameters labeled. Heat Sinks |
유사한 부품 번호 - CS8161YTHA5 |
|
유사한 설명 - CS8161YTHA5 |
|
|
링크 URL |
개인정보취급방침 |
ALLDATASHEET.CO.KR |
ALLDATASHEET 가 귀하에 도움이 되셨나요? [ DONATE ] |
Alldatasheet는? | 광고문의 | 운영자에게 연락하기 | 개인정보취급방침 | 링크교환 | 제조사별 검색 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 |