Intelligent Power
Level 3 Intelligent Power Integration: Topology Control
In addition to Level 1 and Level 2 features, this level permits the standard analog design to be reconfigured, including changing the analog loop configuration and alternating between two different analog control loop filters. For example, a power supply can change from a PWM control loop to a hysteretic control loop at light loads, thereby increasing system efficiency. Switching frequency adjustment can also be used to minimize losses. Microchip's entire range of PIC® MCUs and dsPIC® DSCs can assist in Level 3 control applications.
Level 3 Integration Example
Microchip’s family of Digitally-Enhanced Power Solution offer a Programmable, Hybrid Power Controller combining a mid-voltage analog power stage (including analog control loop, MOSFET drivers, and sensing) with a microcontroller, enabling a user-configurable power converter.
The PIC16F785 can be used in a Level 3 application due to the on-chip analog peripherals. The device has two analog PWM modules that can control power stages. Two error amplifiers and two high-speed comparators can be connected to the PWM modules in many ways through digital configuration. All pins associated with the error amplifiers and comparators are available externally so any type of analog control loop can be created. Twelve ADC inputs are available to monitor power supply operating parameters.
Mixed-signal solutions such as the PIC16F785 integrate an MCU with analog peripherals and are well-suited for topology control. In addition, the MCP1630 and MCP1631 PWM controllers are designed for PIC MCU power controller applications.
Control:
- On/Off only, typically via a SHUTDN input to a traditional analog Switch Mode Power Supply (SMPS) controller
- Proportional control of the SMPS performance, such as output voltage and current
- Topology and Mode control, such as Buck-to-Boost for extended output range, continuous to discontinuous inductor current for zero output current capability, or the ability to add phases as needed
Monitoring:
Any available timing, analog, or digital signals available in the traditional analog SMPS. Including;
- Current in/out
- Voltage in/out
- Temperature
- PWM
Features Possible:
Features relying on On/Off control, such as:
- Level 1 and 2 features
- Continuous/discontinuous inductor current switching
- Multiple loop filter options
- Bypass for low battery operation
- Topology shifts for better efficiency and smaller magnetics
Analog Access Requirements:
- Shutdown and startup control through a SHUTDN input
- Control of reference inputs such as PWM clock, VREF, and ILIMIT
- Analog and digital switching of functional blocks in SMPS design
- Analog, digital and frequency based signals for monitoring
Reliability:
Roughly half of the system reliability is still determined by the traditional analog SMPS design. However, now reliability software begins to dominate due to the possibility of invalid configurations and modes. In addition, switching time during mode and topology changes can introduce transient conditions leading to temporary instabilities.
