SLVS875C January   2009  – November 2014

PRODUCTION DATA.

1. Features
2. Applications
3. Description
1.     Device Images
4. Revision History
5. Pin Configuration and Functions
6. Specifications
7. Detailed Description
1. 7.1 Overview
2. 7.2 Functional Block Diagram
3. 7.3 Feature Description
4. 7.4 Device Functional Modes
8. Application and Implementation
1. 8.1 Application Information
2. 8.2 Typical Application
1. 8.2.1 Design Requirements
2. 8.2.2 Detailed Design Procedure
3. 8.2.3 Application Curves
9. Power Supply Recommendations
10. 10Layout
11. 11Device and Documentation Support
12. 12Mechanical, Packaging, and Orderable Information

• DDA|8
• DDA|8

#### 8.2.2.11 Power Dissipation Estimate

The following formulas show how to estimate the device power dissipation under continuous conduction mode operations. They should not be used if the device is working in the discontinuous conduction mode (DCM) or pulse-skipping Eco-Mode.

The device power dissipation includes:

1. Conduction loss: Pcon = Iout2 x RDS(on) x VOUT/VIN
2. Switching loss: Psw = 0.55 x 10-9 x VIN2 x IOUT x Fsw
3. Gate charge loss: Pgc = 22.8 x 10-9 x Fsw
4. Quiescent current loss: Pq = 0.082 x 10-3 x VIN

Where:

• IOUT is the output current (A).
• RDS(on) is the on-resistance of the high-side MOSFET (Ω).
• VOUT is the output voltage (V).
• VIN is the input voltage (V).
• Fsw is the switching frequency (Hz).
• Ptot = Pcon + Psw + Pgc + Pq
• For given TA , TJ = TA + Rth x Ptot.
• For given TJMAX = 150°C, TAMAX = TJMAX– Rth x Ptot.

Where:

• Ptot is the total device power dissipation (W).
• TA is the ambient temperature (°C).
• TJ is the junction temperature (°C) .
• Rth is the thermal resistance of the package (°C/W).
• TJMAX is maximum junction temperature (°C).
• TAMAX is maximum ambient temperature (°C).