Please teach the calculating formula of the Power Dissipation.
bq51013 Power Dissipation is Rectifying circuit loss+ LDO loss?
Even an electricity loss of LDO exceeds a permission loss at 400mA.
To improve efficiency and provide good load transient response voltage into the LDO (V-RECT) will change with output current. This will result in a change in efficiency as load changes, improving as load increases.
Also below 225mA the synchronous rectifier is operating in a half synchronous mode, but improving as load increases.
Figure 5 in data sheet will give the overall efficiency ( both LDO and Rectifier) as a function of output power.
Figure 4 in the data sheet provides rectifier efficiency as a function of output power.
Below is a breakdown of LDO voltage drop as a function of output current.
LDO input voltage (V-Rect) / LDO Voltage drop:
Less than 100mA – 7.08V / 2.08V
100mA to 200mA – 6.28V / 1.28V
200mA to 400mA – 5.53V / 0.53V
Greater than 400mA – 5.11V / 0.11V
In the case of an output current of 500A at 5V or 2.5W.
Rectifier efficiency is about 95% for a loss of 125mW (5% * 2.5W), see figure 4
LDO at that current will have a 0.11V drop for a loss of 55mW (0.11V * 0.5A).
Total loss is 180mW, this indicates an overall efficiency of about 93%.
Figure 5 indicates a total efficiency of about 93% at 2.5W
Bill Johns, Applications Engineer
bqTESLA Wireless Power Products
Texas Instruments Inc
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.