поискавой системы для электроныых деталей |
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TC1108-3.3VDBTR датащи(PDF) 4 Page - Microchip Technology |
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TC1108-3.3VDBTR датащи(HTML) 4 Page - Microchip Technology |
4 / 12 page TC1108 DS21357C-page 4 2002-2012 Microchip Technology Inc. 4.0 THERMAL CONSIDERATIONS 4.1 Thermal Shutdown Integrated thermal protection circuitry shuts the regulator off when die temperature exceeds 150°C. The regulator remains off until the die temperature drops to approximately 140°C. 4.2 Power Dissipation The amount of power the regulator dissipates is primarily a function of input and output voltage, and output current. The following equation is used to calculate worst case actual power dissipation: EQUATION 4-1: The maximum allowable power dissipation (Equation 4-2) is a function of the maximum ambient temperature (TAMAX), the maximum allowable die temperature (TJMAX) and the thermal resistance from junction-to-air ( JA). EQUATION 4-2: Table 4-1 shows various values of JA for the TC1108 versus board copper area. TABLE 4-1: THERMAL RESISTANCE GUIDELINES FOR TC1108 NOTE: *Tab of device attached to topside copper Equation 4-1 can be used in conjunction with Equation 4-2 to ensure regulator thermal operation is within limits. For example: Given: VINMAX = 3.3V + 10% VOUTMIN = 2.7V – 0.5% ILOADMAX = 275mA TJMAX = 125°C TAMAX = 95°C JA = 59°C/W Find: 1. Actual power dissipation 2. Maximum allowable dissipation Actual power dissipation: PD (VINMAX – VOUTMIN)ILOADMAX = [(3.3 x 1.1) – (2.7 x .995)]275 x 10–3 = 260mW Maximum allowable power dissipation: In this example, the TC1108 dissipates a maximum of 260mW; below the allowable limit of 508mW. In a similar manner, Equation 4-1 and Equation 4-2 can be used to calculate maximum current and/or input voltage limits. For example, the maximum allowable VIN, is found by sustituting the maximum allowable power dissipation of 508mW into Equation 4-1, from which VINMAX = 4.6V. Copper Area (Topside)* Copper Area (Backside) Board Area Thermal Resistance ( JA) 2500 sq mm 2500 sq mm 2500 sq mm 45°C/W 1000 sq mm 2500 sq mm 2500 sq mm 45°C/W 225 sq mm 2500 sq mm 2500 sq mm 53°C/W 100 sq mm 2500 sq mm 2500 sq mm 59°C/W 1000 sq mm 1000 sq mm 1000 sq mm 52°C/W 1000 sq mm 0 sq mm 1000 sq mm 55°C/W Where: PD (VINMAX – VOUTMIN)ILOADMAX VINMAX VOUTMIN ILOADMAX = Worst case actual power dissipation = Minimum regulator output voltage = Maximum output (load) current = Maximum voltage on VIN PD PDMAX = (TJMAX – TAMAX) JA Where all terms are previously defined. PDMAX = (TJMAX – TAMAX) JA = (125 – 95) 59 = 508mW |
Аналогичный номер детали - TC1108-3.3VDBTR |
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Аналогичное описание - TC1108-3.3VDBTR |
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