参数资料
型号: IR3507ZMTRPBF
厂商: International Rectifier
文件页数: 9/19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
An additional advantage of the architecture is that differences in ground or input voltage at the phases have no effect on
operation since the PWM ramps are referenced to VDAC.
Figure 3 depicts PWM operating waveforms under various conditions.
PHASE IC
CLOCK
PULSE
EAIN
PWMRMP
VDAC
GATEH
GATEL
STEADY-STATE
OPERATION
DUTY CYCLE INCREASE
DUE TO LOAD
INCREASE
DUTY CYCLE DECREASE
DUE TO VIN INCREASE
(FEED-FORWARD)
DUTY CYCLE DECREASE DUE TO LOAD
DECREASE (BODY BRAKING) OR FAULT
(VCCLUV, OCP, VID=11111X)
STEADY-STATE
OPERATION
Body Braking
Figure 3: PWM Operating Waveforms
TM
In a conventional synchronous buck converter, the minimum time required to reduce the current in the inductor in
response to a load step decrease is;
T SLEW =
L * ( I MAX ? I MIN )
V O
The slew rate of the inductor current can be significantly increased by turning off the synchronous rectifier in response
to a load step decrease. The switch node voltage is then forced to decrease until conduction of the synchronous
rectifier’s body diode occurs. This increases the voltage across the inductor from Vout to Vout + V BODYDIODE . The
minimum time required to reduce the current in the inductor in response to a load transient decrease is now;
T SLEW =
L * ( I MAX ? I MIN )
V O + V BODYDIODE
Since the voltage drop in the body diode is often comparable to the output voltage, the inductor current slew rate can be
increased significantly. This patented technique is referred to as “body braking” and is accomplished through the “body
braking comparator” located in the phase IC. If the error amplifier’s output voltage drops below the output voltage of the
share adjust amplifier in the phase IC, this comparator turns off the low side gate driver.
Lossless Average Inductor Current Sensing
Inductor current can be sensed by connecting a series resistor and a capacitor network in parallel with the inductor and
measuring the voltage across the capacitor, as shown in Figure 4. The equation of the sensing network is,
v C ( s ) = v L ( s )
1
1 + sR CS C CS
= i L ( s )
R L + sL
1 + sR CS C CS
Page 9 of 19
IR Confidential
April 2, 2009
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