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| 型号： | MAX17410GTM+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 39/45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
Alternatively, shoot-through currents may be caused by
a combination of fast high-side MOSFETs and slow low-
side MOSFETs. If the turn-off delay time of the low-side
MOSFET is too long, the high-side MOSFETs can turn
on before the low-side MOSFETs have actually turned
off. Adding a resistor less than 5 Ω in series with BST
slows down the high-side MOSFET turn-on time, elimi-
nating the shoot-through currents without degrading the
turn-off time (R BST in Figure 10). Slowing down the
high-side MOSFET also reduces the LX node rise time,
thereby reducing EMI and high-frequency coupling
responsible for switching noise.
?
?
Switching Frequency: This choice determines the
basic trade-off between size and efficiency. The
optimal frequency is largely a function of maximum
input voltage, due to MOSFET switching losses that
are proportional to frequency and V IN 2 . The opti-
mum frequency is also a moving target, due to
rapid improvements in MOSFET technology that are
making higher frequencies more practical.
Inductor Operating Point: This choice provides
trade-offs between size vs. efficiency and transient
response vs. output noise. Low inductor values pro-
vide better transient response and smaller physical
? ? ? V OUT ?
V IN OUT
L = η TOTAL ?
? ? ?
I PEAK = ?
? ? ? 1 + 2 ? ?
I LOAD ( PHASE ) = LOAD
Multiphase Quick-PWM
Design Procedure
Firmly establish the input voltage range and maximum
load current before choosing a switching frequency
and inductor operating point (ripple-current ratio). The
primary design trade-off lies in choosing a good switch-
ing frequency and inductor operating point, and the fol-
lowing four factors dictate the rest of the design:
? Input Voltage Range: The maximum value
(V IN(MAX) ) must accommodate the worst-case high
AC adapter voltage. The minimum value (V IN(MIN) )
must account for the lowest input voltage after
drops due to connectors, fuses, and battery selec-
tor switches. If there is a choice at all, lower input
voltages result in better efficiency.
? Maximum Load Current: There are two values to
consider. The peak load current (I LOAD(MAX) ) deter-
mines the instantaneous component stresses and
filtering requirements, and thus drives output
capacitor selection, inductor saturation rating, and
the design of the current-limit circuit. The continu-
ous load current (I LOAD ) determines the thermal
stresses and thus drives the selection of input
capacitors, MOSFETs, and other critical heat-con-
tributing components. Modern notebook CPUs gen-
erally exhibit I LOAD = I LOAD(MAX) x 80%.
For multiphase systems, each phase supports a frac-
tion of the load, depending on the current balancing.
When properly balanced, the load current is evenly dis-
tributed among each phase:
I
η TOTAL
where η TOTAL is the total number of active phases.
size, but also result in lower efficiency and higher
output noise due to increased ripple current. The
minimum practical inductor value is one that causes
the circuit to operate at the edge of critical conduc-
tion (where the inductor current just touches zero
with every cycle at maximum load). Inductor values
lower than this grant no further size-reduction bene-
fit. The optimum operating point is usually found
between 20% and 50% ripple current.
Inductor Selection
The switching frequency and operating point (% ripple
current or LIR) determine the inductor value as follows:
- V
? f SW I LOAD ( MAX ) LIR ? ? V I N ?
where η TOTAL is the total number of phases.
Find a low-loss inductor having the lowest possible DC
resistance that fits in the allotted dimensions. Ferrite
cores are often the best choice, although powdered
iron is inexpensive and can work well at 200kHz. The
core must be large enough not to saturate at the peak
inductor current (I PEAK ):
? I LOAD ( MAX ) ? ? LIR ?
? η TOTAL ?
Transient Response
The inductor ripple current impacts transient-response
performance, especially at low V IN - V OUT differentials.
Low inductor values allow the inductor current to slew
faster, replenishing charge removed from the output fil-
ter capacitors by a sudden load step. The amount of
output sag is also a function of the maximum duty fac-
tor, which can be calculated from the on-time and mini-
mum off-time. For a dual-phase controller, the
worst-case output sag voltage may be determined by:
______________________________________________________________________________________
39
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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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