数据搜索系统,热门电子元器件搜索 |
|
TC551802EZB713 数据表(PDF) 10 Page - Microchip Technology |
|
TC551802EZB713 数据表(HTML) 10 Page - Microchip Technology |
10 / 18 page TC55 DS21435F-page 10 © 2005 Microchip Technology Inc. 5.0 THERMAL CONSIDERATIONS 5.1 Power Dissipation The amount of power dissipated internal to the low dropout linear regulator is the sum of the power dissi- pation within the linear pass device (P-Channel MOS- FET) and the quiescent current required to bias the internal reference and error amplifier. The internal lin- ear pass device power dissipation is calculated by mul- tiplying the voltage across the linear device by the current through the device. EQUATION The internal power dissipation, as a result of the bias current for the LDO internal reference and error amplifier, is calculated by multiplying the ground or quiescent current by the input voltage. EQUATION The total internal power dissipation is the sum of PD (Pass Device) and PD (Bias). EQUATION For the TC55, the internal quiescent bias current is so low (1 µA typical) that the PD (Bias) term of the power dissipation equation can be ignored. The maximum power dissipation can be estimated by using the maximum input voltage and the minimum output voltage to obtain a maximum voltage differential between input and output. The next step would be to multiply the maximum voltage differential by the maximum output current. EQUATION Given: VIN = 3.3V to 4.1V VOUT = 3.0 V ± 2% IOUT = 1 mA to 100 mA TAMAX = 55°C PMAX = (4.1V – (3.0V x 0.98)) x 100 mA PMAX = 116.0 milliwatts To determine the junction temperature of the device, the thermal resistance from junction-to-ambient must be known. The 3-pin SOT-23 thermal resistance from junc- tion-to-air (RθJA) is estimated to be approximately 359°C/W. The SOT-89 RθJA is estimated to be approxi- mately 110°C/W when mounted on 1 square inch of copper. The TO-92 RθJA is estimated to be 131.9°C/W. The RθJA will vary with physical layout, airflow and other application-specific conditions. The device junction temperature is determined by calculating the junction temperature rise above ambient, then adding the rise to the ambient temperature. EQUATION PD (Pass Device) = (VIN – VOUT) x IOUT PD (Bias) = VIN x IGND PTOTAL = PD (Pass Device) + PD (Bias) PD = (VINMAX – VOUTMIN) x IOUTMAX Junction Temperature TJ = PDMAX x RθJA + TA TJ = 116.0 milliwatts x 359°C/W + 55°C TJ = 96.6°C SOT-23 Example: SOT-89 Example: TJ = 116.0 milliwatts x 110°C/W + 55°C TJ = 67.8°C TO-92 Example: TJ = 116.0 milliwatts x 131.9°C/W + 55°C TJ = 70.3°C |
类似零件编号 - TC551802EZB713 |
|
类似说明 - TC551802EZB713 |
|
|
链接网址 |
隐私政策 |
ALLDATASHEETCN.COM |
ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 链接交换 | 制造商名单 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 |