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Hello, Please ask a question about MP8760GLE Datasheet
# Example questions:
➢ What is the recommended range for selecting the switching frequency of the mp8760, and what trade-offs are involved when choosing a frequency within this range?
➢ What determines the on period of the high-side mosfet (hs-fet) at the beginning of each cycle?
➢ How does the mp8760 transition between these two modes, and what condition triggers the switch?
| Part No. | MP8760GLE |
| Manufacturer | MPS |
| Size | 914 Kbytes |
| Pages | 24 pages |
| Description | High Efficiency, 6A, 18V, Synchronous, Step-Down Converter |
1. Overview & Operation Mode
️· What it is: The MP8760 is a fully-integrated synchronous step-down converter (a type of DC-DC converter). It efficiently converts a higher DC voltage to a lower DC voltage.
️· Constant-On-Time (COT) Control: It uses COT control for fast response and easier loop stabilization.
️· Adaptive Operation: It dynamically adapts its operation based on load conditions, switching between modes to maintain efficiency.
2. Operational Modes
️· Heavy-Load (CCM - Continuous Conduction Mode):
- Inductor current always above zero.
- Switching frequency is relatively constant.
- Duty Cycle Calculation: The HS-FET turns on for a fixed period determined by a one-shot timer: `τ ON = (5.3 x R_FREQ (kΩ)) / (V_IN - 0.4)`
️· Light-Load (DCM - Discontinuous Conduction Mode):
- Inductor current drops to zero.
- The converter enters a "skip mode" where it skips some switching cycles to improve efficiency at low loads.
- A current modulator limits the inductor current.
️· Transition: As the load increases from light load, the converter transitions from skip mode to CCM.
3. Switching Frequency
️· Setting the Frequency: The switching frequency is determined by the external resistor (R_FREQ) connected to the FREQ pin and the input voltage:
`f_SW (kHz) = (5.3 x R_FREQ (kΩ) x V_IN) / (V_IN - V_OUT) + τ_DELAY `
Where:
- τ_DELAY is a comparator delay (~40ns).
️· Typical Range: Usually set between 200kHz and 1MHz.
️· Trade-off: Higher frequencies allow for smaller components but can reduce efficiency.
4. Jitter & Feedback Slope
️· Jitter Issues: Noise on the feedback voltage can cause the switching to deviate.
️· Feedback Slope Importance: The steepness of the feedback voltage slope is crucial for noise immunity.
️· ESR Capacitor Considerations: If using capacitors with high Equivalent Series Resistance (ESR), the ESR value needs to be carefully chosen to ensure stability.
5. Key Equations
️· ON Time (PWM): `τ ON = (5.3 x R_FREQ (kΩ)) / (V_IN - 0.4)`
️· Switching Frequency: `f_SW (kHz) = (5.3 x R_FREQ (kΩ) x V_IN) / (V_IN - V_OUT) + τ_DELAY `
️· Critical Output Current (transition to PWM): `I_OUT = (V_IN - V_OUT) x V_OUT / (2 x L x f_SW x V_IN)`
️· ESR Capacitor Requirement (Stability): `R_ESR ≥ 0.7 x π`
1. Overview & Operation Mode
️· What it is: The MP8760 is a fully-integrated synchronous step-down converter (a type of DC-DC converter). It efficiently converts a higher DC voltage to a lower DC voltage.
️· Constant-On-Time (COT) Control: It uses COT control for fast response and easier loop stabilization.
️· Adaptive Operation: It dynamically adapts its operation based on load conditions, switching between modes to maintain efficiency.
2. Operational Modes
️· Heavy-Load (CCM - Continuous Conduction Mode):
- Inductor current always above zero.
- Switching frequency is relatively constant.
- Duty Cycle Calculation: The HS-FET turns on for a fixed period determined by a one-shot timer: `τ ON = (5.3 x R_FREQ (kΩ)) / (V_IN - 0.4)`
️· Light-Load (DCM - Discontinuous Conduction Mode):
- Inductor current drops to zero.
- The converter enters a "skip mode" where it skips some switching cycles to improve efficiency at low loads.
- A current modulator limits the inductor current.
️· Transition: As the load increases from light load, the converter transitions from skip mode to CCM.
3. Switching Frequency
️· Setting the Frequency: The switching frequency is determined by the external resistor (R_FREQ) connected to the FREQ pin and the input voltage:
`f_SW (kHz) = (5.3 x R_FREQ (kΩ) x V_IN) / (V_IN - V_OUT) + τ_DELAY `
Where:
- τ_DELAY is a comparator delay (~40ns).
️· Typical Range: Usually set between 200kHz and 1MHz.
️· Trade-off: Higher frequencies allow for smaller components but can reduce efficiency.
4. Jitter & Feedback Slope
️· Jitter Issues: Noise on the feedback voltage can cause the switching to deviate.
️· Feedback Slope Importance: The steepness of the feedback voltage slope is crucial for noise immunity.
️· ESR Capacitor Considerations: If using capacitors with high Equivalent Series Resistance (ESR), the ESR value needs to be carefully chosen to ensure stability.
5. Key Equations
️· ON Time (PWM): `τ ON = (5.3 x R_FREQ (kΩ)) / (V_IN - 0.4)`
️· Switching Frequency: `f_SW (kHz) = (5.3 x R_FREQ (kΩ) x V_IN) / (V_IN - V_OUT) + τ_DELAY `
️· Critical Output Current (transition to PWM): `I_OUT = (V_IN - V_OUT) x V_OUT / (2 x L x f_SW x V_IN)`
️· ESR Capacitor Requirement (Stability): `R_ESR ≥ 0.7 x π`
| Part No. | MP8760GLE |
| Manufacturer | MPS |
| Size | 914 Kbytes |
| Pages | 24 pages |
| Description | High Efficiency, 6A, 18V, Synchronous, Step-Down Converter |
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