Datasheet BD70522GUL (Rohm) - 7

BD70522GUL 4. On-Time Extension
The On-Time is extended automatically to get the best transient response in the case of high duty cycle operation. If the Main Comp Output does not return to high level within Constant On-Time, the On-Time is extended until the Main Comp Output returns to high, and the maximum On-Time is limited to 16μs. FB + Ramp Compensator VREF Main Comp Output On-Time Extension LX with delay Constant On-Time shot IL Figure 6. On-Time Extension
5. Discharge for VOUT
VOUT pin has a MOSFET for discharge which connects VOUT pin to GND when the IC is in standby state. (EN=Low or UVLO state or TSD state)
6. Power Good (PG) Output
PG pin is an open-drain output. The PG Comp is active when EN pin is set to high and VIN is above the threshold VUVLORLS. PG pin remains low when the VOUT is lower than the PG detection threshold (VPGTH) or during the soft-start time. PG pin goes to high impedance when VOUT exceeds VPGTH. And it is pulled to low level once VOUT falls below the PG release threshold (VPGTH-VPGHYS).
7. Under Voltage Lock Out (UVLO)
UVLO function prevents the malfunction of the internal circuit when VIN is too low. If VIN falls lower than 2.4V (Typ), the IC turns off. In order to prevent from the misdetection of UVLO, it is necessary to set VIN higher than 2.5V (Typ).
8. Over Current Limit (OCL)
BD70522GUL employs a bottom inductor current limit function which is achieved by using the low side MOSFET. Turning on the high side MOSFET is prohibited while the inductor current is higher than the low side OCL (ILIMITL). This function keeps the inductor peak current lower than the sum of ILIMITL and the inductor ripple current. However, the low side OCL function does not work if the VOUT pin is directly shorted to GND. Thus, a high side OCL is implemented for such case. The high side MOSFET turns off when the inductor current exceeds the high side OCL (ILIMITH1). Furthermore, the peak current is limited to ILIMITH1×0.67 under the On-Time extension state. The inductor current is also limited to ILIMITH2 under 100%ON mode, and the high side MOSFET is used to sense the current in this case.
9. Thermal Shutdown (TSD)
BD70522GUL stops the switching operation when the device temperature exceeds the TSD detection threshold 130°C (Typ) for protecting the IC from overheat. After the device temperature falls below the TSD release threshold 115°C (Typ), the IC starts the soft-start operation and recovers to the normal operation. www.rohm.com
TSZ02201-0Q1Q0AJ00400-1-2
© 2017 ROHM Co., Ltd. All rights reserved. 7/24 TSZ22111 • 15 • 001
21.Aug.2017 Rev.002
Document Outline General Description Features Applications Key Specifications Package Typical Application Circuit Contents Pin Configuration Pin Descriptions Block Diagram Absolute Maximum Ratings Thermal Resistance Recommended Operating Conditions Electrical Characteristics Detailed Descriptions Typical Performance Curves Figure 7. Efficiency vs Output Current Figure 8. Efficiency vs Output Current Figure 9. Efficiency vs Output Current Figure 10. Efficiency vs Output Current Figure 11. Output Voltage vs Output Current Figure 12. Output Voltage vs Output Current Figure 13. Output Voltage vs Output Current Figure 14. Output Voltage vs Output Current Figure 15. Switching Frequency vs Output Current Figure 16. Switching Frequency vs Output Current Figure 17. Switching Frequency vs Output Current Figure 18. Switching Frequency vs Output Current Figure 19. Output Ripple Voltage vs Output Current Figure 20. Output Ripple Voltage vs Output Current Figure 21. Output Ripple Voltage vs Output Current Figure 22. Output Ripple Voltage vs Output Current Figure 23. Load Transient Response Figure 24. Load Transient Response Figure 25. Load Transient Response Figure 26. Load Transient Response Figure 27. Line Transient Response Figure 28. Line Transient Response Figure 29. Line Transient Response Figure 30. Line Transient Response Figure 31. Line Transient Response Figure 32. Line Transient Response Figure 33. Line Transient Response Figure 34. Line Transient Response Figure 35. Startup Figure 36. Startup Figure 37. Shutdown Figure 38. Shutdown Figure 39. Input Voltage Ramp Up/Down Figure 40. Input Voltage Ramp Up/Down Figure 41. Input Voltage Ramp Up/Down Figure 42. Input Voltage Ramp Up/Down Timing Chart Application Examples I/O Equivalence Circuits Operational Notes 1. Reverse Connection of Power Supply 2. Power Supply Lines 3. Ground Voltage 4. Ground Wiring Pattern 5. Recommended Operating Conditions 6. Inrush Current 7. Operation Under Strong Electromagnetic Field 8. Testing on Application Boards 9. Inter-pin Short and Mounting Errors 10. Unused Input Pins 11. Regarding the Input Pin of the IC 12. Ceramic Capacitor 13. Area of Safe Operation (ASO) 14. Thermal Shutdown Circuit(TSD) 15. Over Current Protection Circuit (OCP) 16. Disturbance Light Ordering Information Marking Diagram Physical Dimension and Packing Information Revision History