8-bit PIC® Microcontrollers for Power Supplies Closed-Loop Control Made Easy Using Core Independent Peripherals and Intelligent Analog Summary Increased regulation in the home electronics, portable electronics and lighting markets has created several new constraints for the designers of devices for these applications. Lower energy consumption and waste reduction have joined cost effectiveness as primary design objectives for many new systems. Balancing these requirements can be accomplished by using techniques such as Peak Current Mode Control (PCMC) to cost effectively optimize performance and efficiency. In order to achieve these system goals, even the smallest power sources must be flexible, intelligent and able to adapt to changing requirements. Modern power supplies often require controllers designed to support the demands of closedloop control and system management, while being able to communicate with other elements of the system. Levels of Power Supply Control Within the power supply market, there are several different levels of integration and intelligence. With each increase in capability comes a corresponding increase in precision and system efficiency. The most commonly used levels are described below: Level 1: Involves basic control and monitoring functions. The controller provides limited intelligence, with features like start-up sequencing, automatic shutdown and watchdog fault detection. More sophisticated solutions can provide logging functions for failure analysis, remote communication and customized thermal control algorithms. Level 2: Features increased integration with the power supply and allows for better PSU environment monitoring. The controller can adjust output voltage, voltage limits, current limits and thermal limits. PWMs are used to provide direct control of the power unit, which allows the integration of “soft-start” capability. Serial communication is used to communicate with a host device, control cooling fans and monitor temperature sensors. Level 3: Allows for topology control by permitting the design to be reconfigured, including changing the analog loop configuration and control loop filters on the fly. Power supply regulation is directly controlled by digital circuitry. Such control allows for complex digital compensation algorithms and non-linear control techniques to be employed. 8-bit PIC MCUs for Power Supplies Microchip offers a broad range of 8-bit PIC microcontrollers designed to support the increasingly rigorous demands of the modern small power supply. The high integration of peripherals and functions allows for closed-loop control, Peak Current Mode Control (PCMC), HW compensators, Slope Compensation (SC) and ramp generation. By enabling lowcost digital control to implement power conversion functions, PIC MCUs empower you to realize many benefits for your end application. Products within our 8-bit portfolio can support up to “Level 3” topologies by pairing extremely efficient CPU performance with a unique set of Intelligent Analog and Core Independent digital peripherals. The benefits are many, including the ability to implement intelligent system functions like soft-start and voltage slew rate control, digital temperature compensation and remote monitoring and control. In addition, the integrated peripherals support a reduction in component count, PCB size and product cost. Integrated Peripherals Intelligent Analog and Control ■ Zero Cross Detect (ZCD) • AC high-voltage zero crossing detection for simplifying TRIAC control, synchronized switching control and timing ■ Programmable Ramp Generator (PRG) • Analog ramp generator (with slope compensation) for current/voltage-mode power supplies ■ Slope Compensation (SC) • Performs slope compensation function for peak current mode power supplies ■ Configurable Logic Cell (CLC) • Integrated combinational and sequential logic • Custom interconnection and re-routing of digital peripherals ■ Operational Amplifier (OPA) • General purpose op amp for internal and external signal source conditioning ■ High Speed Comparator (HSComp) • General purpose rail-to-rail comparator with < 50 ns response time ■ Digital to Analog Converter (DAC ) • Programmable voltage reference with multiple internal and external connections ■ Analog to Digital Converter (ADC) • General-purpose 8-/10-/12-bit ADC with stable voltage reference Integrated Peripherals (Continued) ■■ Complementary Output Generator (COG) • Automated complementary output with programmable rising/falling edge events, auto shutdown, polarity, phase, precision deadband and blanking control ■■ Complementary Waveform Generator (CWG) • Automated complementary output with auto shutdown and deadband control ■■ Numerically Controlled Oscillator (NCO) • Precision linear frequency generator (PWM @ 50% duty cycle) with 0.0001% step size of source input clock frequency • General-purpose 20-bit timer/counter Signal Generation ■■ Programmable Switch Mode Controller (PSMC) • 16-bit PWMs with dedicated 64 MHz clock • Automated complementary output with programmable rising/falling edge events, auto shutdown, polarity, phase, deadband and blanking control • General-purpose 16-bit timer/counter ■■ 16-bit PWM • 16-bit PWM with edge and center aligned modes • General-purpose 16-bit timer/counter ■■ Pulse Width Modulation (PWM) • General-purpose 10-bit PWM ■■ (Enhanced) Capture Compare PWM (CCP/ECCP) • 10-bit PWM control with 16-bit capture, compare and auto shutdown – – 1 – 1 0/1 1 – – – – 1 – 3 – – 0/1 – – – – 1 PIC12F1840 7K 256 256 6 0/4/0 – – 1 0/1 – – – – – – – 1 1 PIC12F752 1.75K 64 HEF* 6 0/4/0 – 1/0/0/0 2 1/0 – – – 1/0 – – – – – PIC16F753 3.5K 128 HEF* 12 0/8/0 2 0/1/0/0 2 1/0 – – – 1/0 – 0/1 – – – PIC16F1765 14K 1K HEF* 12 0/8/0 1 1/0/0/1 2 1/0 2 – – 1/0 3 1/0 1 1 1 PIC16F1825 14K 1K 256 12 0/8/0 – – 2 2/2 – – – – – – – 1 1 PIC16F1709 14K 1K HEF* 18 0/12/0 2 0/1/0/0 2 2/0 2 – – 1/0 3 – 1 1 1 PIC16F1769 14K 1K HEF* 18 0/12/0 2 2/0/0/2 4 2/0 4 – – 2/0 3 2/0 1 1 1 PIC18F14K22 16K 512 256 18 0/12/0 – – 2 0/1 – – – – – – – 1 1 PIC16F1789 28K 2K 256 36 0/0/14 3 3/1/0/0 4 3/0 – 4 – – – – – 1 1 EEPROM EUSART – 1/0/0/0 i2C/SPI CLC – – ZCD COG/CWG 3/0/0 0/4/0 PRG/SC NCO 4 6 PWM – HEF* Op Amp 64 256 A/D (Ch) 8/10/12b 896 3.5K I/O Pins PIC10F322 PIC12F1572 Device SRAM(B) PSMC CCP/ECCP Comparator DAC 5/8/9/10b Program Memory (B) Select 8-bit PIC MCUs for Power Supplies *HEF = 128B of High-Endurance Flash Development Tools ■■ PICkit™ 3 In-Circuit Debugger (PG164130) ■■ MPLAB® ICD 3 In-Circuit Debugger (DV164035) ■■ PSMC Evaluation Platform (DM164130-1) ■■ ■■ ■■ ■■ PICDEM™ Lab Development Kit (DM13045) MPLAB PM3 Universal Device Programmer (DV007004) MPLAB Starter Kit for PIC18F MCU (DM180021) PICDEM PIC18 Explorer Board (DM183032) www.microchip.com/8bit Visit our web site for additional product information and to locate your local sales office. Microchip Technology Inc. • 2355 W. Chandler Blvd. • Chandler, AZ 85224-6199 The Microchip name and logo, the Microchip logo, MPLAB and PIC are registered trademarks and PICDEM and PICkit are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. All other trademarks mentioned herein are property of their respective companies. © 2015, Microchip Technology Incorporated. All Rights Reserved. Printed in the U.S.A. 8/15 DS30010027C