Table 2. Design Parameters

8.2.2.1 Capacitors

The LM2753 requires three external capacitors for proper operation. TI recommends surface-mount multi-layer ceramic capacitors. These capacitors are small, inexpensive and have very low equivalent series resistance (ESR) ( ≤ 15 mΩ typical). Tantalum capacitors, OS-CON capacitors, and aluminum electrolytic capacitors are generally not recommended for use with the LM2753 due to their high ESR, as compared to ceramic capacitors.

For most applications, ceramic capacitors with X7R or X5R temperature characteristic are preferred for use with the LM2753. These capacitors have tight capacitance tolerance (as good as ±10%), hold their value over temperature (X7R: ±15% over −55°C to +125°C; X5R: ±15% over −55°C to +85°C), and typically have little voltage coefficient when compared to other types of capacitors. However, selecting a capacitor with a voltage rating much higher than the voltage it will be subjected to ensures that the capacitance stays closer to the nominal value of the capacitor. Capacitors with Y5V or Z5U temperature characteristic are generally not recommended for use with the LM2753. Capacitors with these temperature characteristics typically have wide capacitance tolerance (+80%, −20%), vary significantly over temperature (Y5V: 22%, −82% over −30°C to +85°C range; Z5U: 22%, −56% over 10°C to 85°C range), and have poor voltage coefficients. Under some conditions, a nominal 1-µF Y5V or Z5U capacitor could have a capacitance of only 0.1 µF. Such detrimental deviation is likely to cause Y5V and Z5U capacitors to fail to meet the minimum capacitance requirements of the LM2753. Table 3 lists suggested capacitor suppliers for the typical application circuit.

Table 3. Ceramic Capacitor Manufacturers

8.2.2.2 Power Dissipation

The power dissipation (P_DISSIPATION) and junction temperature (T_J) can be approximated with Equation 3 and Equation 4. P_IN is the product of the input current and input voltage, P_OUT is the power consumed by the load connected to the output, T_A is the ambient temperature, and R_θJA is the junction-to-ambient thermal resistance for the 10-pin WSON package.

The junction temperature rating takes precedence over the ambient temperature rating. The LM2753 may be operated outside the ambient temperature rating, so long as the junction temperature of the device does not exceed the maximum operating rating of 120°C. The maximum ambient temperature rating must be derated in applications where high power dissipation and/or poor thermal resistance causes the junction temperature to exceed 120°C.