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| 型号： | MAX17410GTM+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 24/45页 |
| 文件大小： | 0K |
| 描述： | IC CTLR QPWM 2PH FOR IMV 48TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | * |
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Dual-Phase, Quick-PWM Controller
for IMVP6+ CPU Core Power Supplies
The one-shot for the secondary phase varies the on-
time in response to the input voltage and the difference
between the main and secondary inductor currents.
dead time. For loads above the critical conduction point,
where the dead-time effect is no longer a factor, the
actual switching frequency (per phase) is:
t ON ( V IN + V DIS CHG )
Two identical transconductance amplifiers integrate the
difference between the master and slave current-sense
signals. The summed output is internally connected to
CCI, allowing adjustment of the integration time con-
f SW =
( V OUT + V DIS )
- V
t ON ( SEC ) = t SW ? CCI
= t SW ? FB
? ? + t SW ? ?
R CS = ?
? R 2 ?
? R 1 + R 2 ? ? DCR
stant with a compensation network connected between
CCI and FB. The resulting compensation current and
voltage are determined by the following equations:
I CCI = G m ( V CSP 1 - V CSN 1 ) - G m ( V CSP 2 - V CSP 2 )
V CCI = V FB + I CCI Z CCI
where Z CCI is the impedance at the CCI output. The
secondary on-time one-shot uses this integrated signal
(V CCI ) to set the secondary high-side MOSFET’s on-
time. When the main and secondary current-sense sig-
nals become unbalanced, the transconductance
amplifiers adjust the secondary on-time, which increas-
es or decreases the secondary inductor current until
the current-sense signals are properly balanced:
? V + 0.075 V ?
?
? V IN ?
? V + 0 . 0775V ? ? I CCI Z CCI ?
?
? V IN V IN ?
= ( Main On-ttime ) + ( Secondary Current Balance Correctio n )
This algorithm results in a nearly constant switching fre-
quency and balanced inductor currents despite the
lack of a fixed-frequency clock generator. The constant
switching frequency allows the inductor ripple-current
operating point to remain relatively constant, resulting
in easy design methodology and predictable output
voltage ripple.
On-times translate only roughly to switching frequencies.
The on-times guaranteed in the Electrical Characteristics
where V DIS is the sum of the parasitic voltage drops in
the inductor discharge path, including synchronous
rectifier, inductor, and PCB resistances; V CHG is the
sum of the parasitic voltage drops in the inductor
charge path, including high-side switch, inductor, and
PCB resistances; and t ON is the on-time as defined in
the Electrical Characteristics table.
Current Sense
The output current of each phase is sensed. Low offset
amplifiers are used for current balance, voltage-
positioning gain, and current limit. Sensing the current at
the output of each phase offers advantages, including less
noise sensitivity, more accurate current sharing between
phases, and the flexibility of using either a current-sense
resistor or the DC resistance of the output inductor.
Using the DC resistance (R DCR ) of the output inductor
allows higher efficiency. In this configuration, the initial
tolerance and temperature coefficient of the inductor’s
DCR must be accounted for in the output-voltage droop-
error budget and power monitor. This current-sense
method uses an RC filtering network to extract the current
information from the output inductor (see Figure 3). The
resistive divider used should provide a current-sense
resistance (R CS ) low enough to meet the current-limit
requirements, and the time constant of the RC network
should match the inductor’s time constant (L/R CS ):
R
and:
? R 1 + R 2 ?
table are influenced by switching delays in the external
high-side MOSFET. Resistive losses, including the induc-
tor, both MOSFETs, output capacitor ESR, and PCB cop-
per losses in the output and ground tend to raise the
R CS =
L ? 1 1 ?
C EQ ? ?
switching frequency at higher output currents. Also, the
dead-time effect increases the effective on-time, reduc-
ing the switching frequency. It occurs only during forced-
PWM operation and dynamic output voltage transitions
when the inductor current reverses at light or negative
load currents. With reversed inductor current, the induc-
tor’s EMF causes LX to go high earlier than normal,
extending the on-time by a period equal to the DH rising
where R CS is the required current-sense resistance, and
R DCR is the inductor’s series DC resistance. Use the
worst-case inductance and R DCR values provided by
the inductor manufacturer, adding some margin for the
inductance drop over temperature and load. To mini-
mize the current-sense error due to the current-sense
inputs’ bias current (I CSP _ and I CSN _), choose R1 || R2
to be less than 2k Ω and use the above equation to
24
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17411GTM+ | 功能描述:电流型 PWM 控制器 IMVP7 CPU & Graphics Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX17411GTM+T | 功能描述:电流型 PWM 控制器 IMVP7 CPU & Graphics Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX17411RGTM+ | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX17411RGTM+T | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX17411RGTM+TW | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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