MAX77812四相大电流降压稳压器解析（优势、电路图、特性）

Maxim公司的MAX77812是四相大电流降压稳压器,输入电压从2.5V到5.5V,输出电压从0.25V到1.525V,每步5mV,最大输出电流20A,DC输出电压精度±0.5%, 3.8VIN, 1.1VOUT,L = 220nH (9mΩ DCR)时的峰值效率91%,主要用在智能手机和平板电脑,游戏控制台,DSLR照相机,无人驾驶飞机,微处理器(CPU/GPU)和FPGA以及通信模块.本文介绍了MAX77812主要优势和特性,框图,应用框图以及评估板MAX77812 EVK主要特性,电路图,材料清单和PCB设计图.

The MAX77812 is a quad-phase, high-current, buck regulator for multicore applications processors in the lat­est smart phones and tablets. The MAX77812 achieves world-class transient response with miniature PCB foot­print through the use of small inductors and output capaci­tors. Differential remote sense feedback enables tight DC and AC accuracy at the point of load. The MAX77812’s flexible architecture allows user-selectable phase configu­rations such as 4, 3 + 1, 2 + 2, 2 + 1 + 1, and 1 + 1 + 1 + 1.

Programmable current limit minimizes inductor size given the system’s actual requirements. Programmable soft-start ramp rate, rising and falling ramp rates, and startup operation provide control over inrush current as the regulator transitions between operating states. An output voltage range of 0.25V to 1.525V supports a wide range of application processors, down to the lowest power retention states.

Multifunction general-purpose inputs and high-speed serial interface provide flexible enable control of each regulator, DVS operation, and output voltage ramp rate control that enables rapid output voltage adjustment to optimize performance in all system operating states.

The MAX77812 features I2C-compatible, 2-wire serial interface consisting of a bidirectional serial data line (SDA) and a serial clock line (SCL). The MAX77812 I2C supports SCL clock rates up to 3.4MHz. The MAX77812 I2C can be configured as a 26MHz (typ) SPI interface by I2C_SPI_SEL input pin.

The MAX77812 is available in a 64-bump 0.4mm pitch WLP package with a maximum height of 0.8mm

MAX77812主要优势和特性:

20A Maximum Output Current
2.5V to 5.5V Input Voltage Range
Output Voltage Range from 0.25V to 1.525V in 5mV Steps
±0.5% Typical DC Output Voltage Accuracy
91% Peak Efficiency at 3.8VIN, 1.1VOUT,L = 220nH (9mΩ DCR)
Enhanced Load Transient Response
Programmable Ramp-Up and Ramp-Down Slew Rate
Auto (SKIP/PWM) or Forced PWM Modes
User-Selectable Phase Configurations
Multifunction General-Purpose Inputs
Watchdog Timer Reset Input
Interrupt Output for Status and Fault Conditions
High-Speed (Up to 3.4MHz) I2C Serial Interface with an Option for 30MHz SPI Interface

MAX77812应用:

Smartphones and Tablets
Game Consoles
DSLR Cameras
Drones
Micro Processors (CPU/GPU) and FPGAs
Communication Modules

图1.MAX77812简化框图

图2. MAX77812典型应用框图

评估板MAX77812 EVK

The MAX77812 evaluation kit (EV kit) is a fully assembled and tested printed circuit board (PCB) that demonstrates the MAX77812. The EV kit allows for easy evaluation of each feature. It supports user-programmable phase con­figuration to one of five options:
Single output in 4 phase configuration (default)
Dual outputs in 3 + 1 phase configuration
Dual outputs in 2 + 2 phase configuration
Three outputs in 2 + 1 + 1 phase configuration
Four outputs in 1 + 1 + 1 + 1 phase configuration
A Micro-B USB cable is included in the package to serve as the USB to I2C interface for easy testing. Windows®- based software provides a user-friendly interface to exer­cise the features of the MAX77812. This software offers a graphical user interface (GUI) as well as a register-based interface.

评估板MAX77812 EVK主要特性:

20A Maximum Output Current
2.5V to 5.5V Input Voltage Range
Output Voltage Range from 0.25V to 1.525V in 5mV Steps
±0.5% (typ) DC Output Voltage Accuracy
91% Peak Efficiency at 3.8VIN 1.1VOUT, L = 220nH (9mΩ DCR)
Enhanced Load Transient Response
Programmable Ramp-Up and Ramp-Down Slew Rate
Auto (SKIP/PWM) or Forced PWM Modes
User-Selectable Phase Configurations
Multifunction General-Purpose Inputs
Watchdog Timer Reset Input
Interrupt Output for Status and Fault Conditions
High-Speed (Up to 3.4MHz) I2C Serial Interface with an Option for 30MHz SPI Interface

图3.评估板MAX77812 EVK外形图

图4.评估板MAX77812 EVK电路图(1)

图5.评估板MAX77812 EVK电路图(2)
评估板MAX77812 EVK材料清单:

图6.评估板MAX77812 EVK PCB设计图(1):顶层丝印

图7.评估板MAX77812 EVK PCB设计图(2):顶层布局

图8.评估板MAX77812 EVK PCB设计图(3):内层2布局

图9.评估板MAX77812 EVK PCB设计图(4):内层3布局

图10.评估板MAX77812 EVK PCB设计图(5):内层4布局

图11.评估板MAX77812 EVK PCB设计图(6):内层5布局

图12.评估板MAX77812 EVK PCB设计图(7):底层布局

图13.评估板MAX77812 EVK PCB设计图(8):底层丝印