Maxim MAX17007 QPWM电源方案

Maxim公司的MAX17007是双路Quick-PWM降压控制器,两种开关电源能组合起来成为两相单输出模式,可以提供更高的输出电流,主要用于以电池为能源的系统.开关频率可在200kHz 和600kHz之间用外接电阻单独调整. MAX17007还具有过压,欠压以及热保护等功能.可以应用在笔记本电脑,低功耗的I/O电源,GPU内核电源,以及2-4节锂离字电池的电源系统.本文介绍了MAX17007主要性能,功能图以及独立模式与组合模式的标准应用电路图.

Dual and Combinable QPWM Graphics Core Controllers for Notebook Computers
The MAX17007/MAX17008 are dual Quick-PWM™ stepdown controllers intended for general power generation in battery-powered systems. The two switched-mode power supplies (SMPSs) can also be combined to operate in a two-phase single-output mode. Constant ontime Quick-PWM operation provides fast response to load transients and handles wide input/output (I/O) voltage ratios with ease, while maintaining a relatively constant switching frequency. The switching frequency can be individually adjusted between 200kHz and 600kHz with external resistors. Differential output current sensing
allows output sense-resistor sensing for an accurate current limit, or lossless inductor direct-current resistance (DCR) current sensing for lower power dissipation while maintaining 0.7% output accuracy. Overvoltage (MAX17007 only), undervoltage protection, and accurate user-selectable current limits (15mV, 30mV, 45mV, and 60mV) ensure robust operations.

The SMPS outputs can operate in skip mode or in ultrasonic mode for improved light-load efficiency. The ultrasonic mode eliminates audible noises by maintaining a minimum switching frequency of 25kHz in pulseskipping mode.
The output voltage of SMPS1 can be dynamically adjusted by changing the voltage at the REFIN1 pin. The device includes a 0.5% accurate reference output that can be used to set the REFIN1 voltage. An external 5V bias supply is required to power the internal circuitry and its gate drivers.

Independent on/off controls with well-defined logic thresholds and independent open-drain power-good outputs provide flexible system configurations. To prevent current
surges at startup, the internal voltage target is slowly ramped up from zero to the final target with a slew rate of 1.3mV/μs for SMPS1 at CSL1 and 0.65mV/μs for SMPS2
at FB2. To prevent the output from ringing off below ground in shutdown, the internal voltage target is ramped down from its previous value to zero with the same respective slew rates. Integrated bootstrap switches eliminate the need for external bootstrap diodes.

The MAX17007/MAX17008 are available in a spacesaving, 28-pin, 4mm x 4mm, thin QFN package with an exposed backside pad.

Features
Dual Quick-PWM with Fast Transient Response
Automatic Dynamic REFIN1 Detection and PGOOD1/Fault Blanking
Fixed and Adjustable Output Voltages 0.7% Output Accuracy Over Line and Load
OUT1: 0 to 2V Dynamic Output or Preset 1.05V
OUT2: 0.7V to 2V Range or Preset 1.5V
Resistor-Programmable Switching Frequency
Integrated BST Switches
Differential Current-Sense Inputs
Low-Cost DCR Sensing or Accurate Current- Sense Resistors
Internally Coupled Current-Sense Compensation
Combinable Mode Supports High-Current Dynamic Output Voltages
Selectable Forced-PWM, Pulse Skip, or Ultrasonic Mode Operation
26V Maximum Input Voltage Rating
Independent Enable Inputs
Independent Power-Good Outputs
Overvoltage Protection (MAX17007 Only)
Undervoltage/Thermal Protection
Automatic Dynamic REFIN1 Detection and PGOOD1/Fault Blanking
Voltage Soft-Start and Soft-Shutdown

应用:
Notebook Computers
Low-Power I/O Supplies
GPU Core Supplies
5V and 3.3V Supplies
2 to 4 Li+ Cells Battery- Powered Devices



图1.MAX17007/MAX17008 功能图



图2.MAX17007/MAX17008独立模式标准应用电路



图3.MAX17007/MAX17008组合模式标准应用电路