参数资料
| 型号： | IR3507ZMTRPBF |
| 厂商： | International Rectifier |
| 文件页数： | 10/19页 |
| 文件大小： | 0K |
| 描述： | IC CTRL XPHASE3 20-MLPQ |
| 标准包装： | 3,000 |
| 系列： | XPhase3™ |
| 应用： | 处理器 |
| 电流 - 电源： | 4mA |
| 电源电压： | 8 V ~ 28 V |
| 工作温度： | 0°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-MLPQ |
| 供应商设备封装： | 20-MLPQ（4x4） |
| 包装： | 带卷 (TR) |
IR3507Z
Usually the resistor Rcs and capacitor Ccs are chosen so that the time constant of Rcs and Ccs equals the time
constant of the inductor which is the inductance L over the inductor DCR (R L ). If the two time constants match, the
voltage across Ccs is proportional to the current through L, and the sense circuit can be treated as if only a sense
resistor with the value of R L was used. The mismatch of the time constants does not affect the measurement of inductor
DC current, but affects the AC component of the inductor current.
v L
i L
Current
Sense Amp
L
R CS
R L
C CS
c
v CS
V O
C O
CSOUT
Figure 4: Inductor Current Sensing and Current Sense Amplifier
The advantage of sensing the inductor current versus high side or low side sensing is that actual output current being
delivered to the load is obtained rather than peak or sampled information about the switch currents. The output voltage
can be positioned to meet a load line based on real time information. Except for a sense resistor in series with the
inductor, this is the only sense method that can support a single cycle transient response. Other methods provide no
information during either load increase (low side sensing) or load decrease (high side sensing).
An additional problem associated with peak or valley current mode control for voltage positioning is that they suffer from
peak-to-average errors. These errors will show in many ways but one example is the effect of frequency variation. If the
frequency of a particular unit is 10% low, the peak to peak inductor current will be 10% larger and the output impedance
of the converter will drop by about 10%. Variations in inductance, current sense amplifier bandwidth, PWM prop delay,
any added slope compensation, input voltage, and output voltage are all additional sources of peak-to-average errors.
Current Sense Amplifier
A high speed differential current sense amplifier is located in the phase IC, as shown in Figure 4. Its gain is nominally
32.5, and the 3850 ppm/oC increase in inductor DCR should be compensated in the voltage loop feedback path.
The current sense amplifier can accept positive differential input up to 50mV and negative up to -10mV before clipping.
The output of the current sense amplifier is summed with the DAC voltage and sent to the control IC and other phases
through an on-chip 3K ? resistor connected to the IOUT pin. The IOUT pins of all the phases are tied together and the
voltage on the share bus represents the average current through all the inductors and is used by the control IC for
voltage positioning and current limit protection. The input offset of this amplifier is calibrated to +/- 1mV in order to
reduce the current sense error.
The input offset voltage is the primary source of error for the current share loop. In order to achieve very small input
offset error and superior current sharing performance, the current sense amplifier continuously calibrates itself. This
calibration algorithm creates ripple on IOUT bus with a frequency of f sw /(32*28) in a multiphase architecture.
Average Current Share Loop
Current sharing between phases of the converter is achieved by the average current share loop in each phase IC. The
output of the current sense amplifier is compared with the average current at the share bus. If current in a phase is
smaller than the average current, the share adjust amplifier of the phase will pull down the starting point of the PWM
ramp thereby increasing its duty cycle and output current; if current in a phase is larger than the average current, the
share adjust amplifier of the phase will pull up the starting point of the PWM ramp thereby decreasing its duty cycle and
output current. The current share amplifier is internally compensated so that the crossover frequency of the current
Page 10 of 19
IR Confidential
April 2, 2009
相关PDF资料 |
PDF描述 |
|---|---|
| IR3508MTRPBF | IC XPHASE3 CTLR 20-MLPQ |
| IR3508ZMTRPBF | IC CTRL XPHASE3 20MLPQ |
| IR3510MPBF | IC XPHASE CONTROL 32-MLPQ |
| IR3513ZMTRPBF | IC CTRL XPHASE3 POL 32-MLPQ |
| IR3514MTRPBF | IC XPHASE3 CONTROL HYBRD 40-MLPQ |
相关代理商/技术参数 |
参数描述 |
|---|---|
| IR3508 | 制造商:IRF 制造商全称:International Rectifier 功能描述:XPHASE3TM PHASE IC |
| IR3508MPBF | 制造商:IRF 制造商全称:International Rectifier 功能描述:XPHASE3TM PHASE IC |
| IR3508MTRPBF | 功能描述:开关变换器、稳压器与控制器 XPHASE3 DDR VTT 7V 2A 3 Wire RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| IR3508Z | 制造商:IRF 制造商全称:International Rectifier 功能描述:XPHASE3TM PHASE IC |
| IR3508ZMPBF | 制造商:IRF 制造商全称:International Rectifier 功能描述:XPHASE3TM PHASE IC |
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