新闻中心

EEPW首页 > 模拟技术 > 设计应用 > Implementing a MAX1385-Based C

Implementing a MAX1385-Based C

作者:时间:2011-12-28来源:网络收藏
Abstract: Maxim's evaluation kit (EV kit) software includes a Windows® graphical user interface (GUI) program; however, the time cost of updating this display interferes with the control loop. This application note shows a more optimal control-loop program, using a console menu system instead of a GUI.

When used with the EVKIT+ demo board, the control loop achieves a regulation accuracy of ±2%. This accuracy is limited by the gate driver output step size and the FET transconductance. Drain-current regulation step size is determined by the 's gate-voltage increment multiplied by the FET's effective transconductance. Because the MAX1385EVKIT uses an IRFZ44N MOSFET to close the loop for demonstration purposes, the regulation may not be the same as it would be when used with an LDMOS FET.

Required Hardware

  • Maxim MAX1385EVKIT+
  • Maxim MAXQUSB+ (includes USB A-B cable)
  • Windows 2000/XP P with USB port
  • 5VD at 100mA power supply
  • 10VDC at 1000mA power supply
  • DMM for measuring drain current
  • DMM for measuring drain voltage
  • DMM for measuring PGAOUT amplified current-sense voltage
  • Optional: oscilloscope for monitoring GATE1 voltage and PGAOUT1 drain current

Setup

Download and unzip the necessary executable and source code files (ZIP, 736kB).

Assemble the hardware according to Figure 1.
  • Plug the CMAXQUSB header P3 into the MAX1385EVKIT connector J1.
  • Connect the MAX1385EVKIT's DRAIN1 and DRAIN2 pins to the current meter (-).
  • Connect the current meter (+) to the power supply (+).
  • Connect the MAX1385EVKIT's SOURCE1 and SOURCE2 pins to the power supply (-).
  • Connect the voltage meter (+) to the MAX1385EVKIT's DRAIN1 pin.
  • Connect the voltage meter (-) to the MAX1385EVKIT's SOURCE1 pin.
  • Connect the MAX1385EVKIT's AVDD pin to the DVDD pin (or, optionally, connect to an external 5V DC supply).
Implementing a MAX1385-Based C
More Detailed Image (PDF, 387kB)
Figure 1. MAX1385EVKIT hardware configuration.

Procedure

Set the CMAXQUSB's VDD Select jumper to the 5V position.

Connect the CMAXQUSB to the PC's USB port. If this is the first time a CMAXQUSB has been attached to the PC, the plug-and-play wizard will appear. Guide the GUI to the installed location of the device driver, in MAX1385_Appnote_src.zip\src\USB_driver.

Start the DEMO1385.EXE program. A console will appear on the screen. Enter the following series of commands at the console:

CommandAction
CConnects to the CMAXQUSB module. Verify that the software reports: Board connected.
Got board banner: Maxim CMAXQUSB V01.04.32 >Searching for MAX1385...Found MAX1385 at 0x4eNote: when using MAX1385EVKIT with CMAXQUSB,connect 5V DVDD supply to AVDD.
T V PTest menu/verify power-up values
T S O FCT1 0300Test menu/servo mode/output register/FineCalThru1 register, initial value 0x0300
T S I FFTest menu/servo mode/input register/FIFO register
T S A 2Test menu/servo mode/ADC command/trigger channel 2 (current CS1)
T S T 0020Test menu/servo mode/target value 0x0020
T S C 1Test menu/servo mode/convergence step positive 1
T S H 1Test menu/servo mode/hysteresis one step
T S M 60000Test menu/servo mode/maximum loop duration set to 60 seconds
T S RTest menu/servo mode/run
T W FCT1 0300Test menu/write register/FineCalThru1 register, value 0x0300

Monitor the regulation by watching the DMM.

The voltage on PGAOUT1 regulates between 20.8mV and 21.7mV, which is a variation of 0.45mV (2%) around an average of 21.25mV.

Source Code Walk-Through

The source code was developed with the free dev-cpp IDE, which uses the GNU gcc-3.4.2 C++ compiler.

Listing 1 shows a simplified version of the C++ code performed inside the regulation loop. Output statements and error handling have been removed for clarity.

Listing 1. Simplified C++ code.
Implementing a MAX1385-Based C

Menu System

The complete source code implements the console menu system seen in Listing 2, which connects to the CMAXQUSB module.

Listing 2. Console menu system.
============================================================CmodComm test program main menu when not connectedA) adjust timing parametersL) CmodLog... functionsC) connectD) Debug MessagesX) exit---------------------------------------------CBoard connected.Got board banner: Maxim CMAXQUSB V01.04.32 >Searching for MAX1385...Found MAX1385 at 0x4eNote: when using MAX1385EVKIT with CMAXQUSB,connect 5V DVDD supply to AVDD.============================================================CmodComm test program main menu after successful connectT) Test the device8) CmodP8Bus... functionsA) adjust timing parametersL) CmodLog... functionsP) CmodPin... functionsS) CmodSpi... functionsM) CmodSMBus... functions$) CmodCommStringWrite list of hex codesR) CmodBoardResetD) Disconnect============================================================T Test menuT ?                     Hunt for active devicesT R                     Read registerT W                     Write registerT S                     Servo loopT VP                    Verify Power-On Register ValuesT VM reg mask           Verify Register Memory Persistence, All Combinations ...T VW reg mask           Verify Register Memory Persistence, Walking-One's test ...============================================================Write register:T W AD                  Write ADCCONT W AH                  Write ALMHCFGT W AS                  Write ALMSCFGT W FI1                 Write FINE1T W FI2                 Write FINE2T W FC1                 Write FINECAL1T W FC2                 Write FINECAL2T W FCT1                Write FINECALTHRU1T W FCT2                Write FINECALTHRU2T W FT1                 Write FINETHRU1T W FT2                 Write FINETHRU2T W HC                  Write HCFGT W HT1                 Write THRUHI1T W HT2                 Write THRUHI2T W HW1                 Write HIWIPE1T W HW2                 Write HIWIPE2T W IH1                 Write IH1T W IH2                 Write IH2T W IL1                 Write IL1T W IL2                 Write IL2T W LD                  Write LDACT W LT1                 Write THRULO1T W LT2                 Write THRULO2T W LW1                 Write LOWIPE1T W LW2                 Write LOWIPE2T W P                   Write PGACALT W SC                  Write SCLRT W SS                  Write SSHUTT W TH1                 Write TH1T W TH2                 Write TH2T W TL1                 Write TL1T W TL2                 Write TL2T W X /hexRegAddr/      Write any register by its hexadecimal address============================================================Read register:T R AH                  Read ALMHCFGT R AS                  Read ALMSCFGT R FF                  Read FIFOT R FI1                 Read FINE1T R FI2                 Read FINE2T R FL                  Read FLAGT R HC                  Read HCFGT R HW1                 Read HIWIPE1T R HW2                 Read HIWIPE2T R IH1                 Read IH1T R IH2                 Read IH2T R IL1                         Read IL1T R IL2                         Read IL2T R LW1                 Read LOWIPE1T R LW2                 Read LOWIPE2T R TH1                 Read TH1T R TH2                 Read TH2T R TL1                 Read TL1T R TL2                 Read TL2T R X /hexRegAddr/      Read any register by its hexadecimal address============================================================T S Test Servo menuT S O FCT1 0300 output register [wr_FINECALTHRU1, initial value 0x0300]T S I FF        input register [rd_FIFO]T S A 2         ADC input channel [ bit 2 = 0x0004 = ADCCON_CURRENT_CS1 ]T S T 0020      target value [0x0020]T S C 1         ConvergeStep [1]T S H 1         hysteresis [1]T S M 60000     max_loop_duration_msec [60000]T S R           servo loop run============================================================

Windows is a registered trademark of Microsoft Corp.



关键词: MAX1385 Based C

评论


相关推荐

技术专区

关闭