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| 型号： | MAX17007GTI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 28/35页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR QPWM GRAPHICS 28TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | Quick-PWM™ |
| 应用： | 电源 |
| 电流 - 电源： | 1.7mA |
| 电源电压： | 4.5 V ~ 26 V |
| 工作温度： | -40°C ~ 105°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
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Dual and Combinable QPWM Graphics
Core Controllers for Notebook Computers
L = ?
f SW LOAD ( MAX ) LIR ? ? ? V IN ? ?
?
Quick-PWM Design Procedure
Firmly establish the input voltage range and maximum
load current before choosing a switching frequency
?
?
I
V IN ? V OUT ? ? V OUT ?
L = ?
? = 0 . 97 μ H
? 300 kHz × 15 A × 0 . 3 ? ? 12 V ?
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 input
supply voltage allowed by the notebook ’s 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.
For example: I LOAD(MAX) = 15A, V IN = 12V, V OUT =
1.5V, f SW = 300kHz, 30% ripple current or LIR = 0.3:
? 12 V ? 1 . 5 V ? ? 1 . 5 V ?
? ?
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 PEAK = I LOAD ( MAX ) ? 1 +
2 ?
?
Maximum load current: There are two values to
consider. The peak load current (I LOAD(MAX) ) deter-
mines the instantaneous component stresses and fil-
?
?
LIR ?
?
tering requirements, and thus drives output
capacitor selection, inductor saturation rating, and
the design of the current-limit circuit. The continuous
load current (I LOAD ) determines the thermal stress-
es and thus drives the selection of input capacitors,
MOSFETs, and other critical heat-contributing com-
ponents. Most notebook loads generally exhibit
I LOAD = I LOAD(MAX) x 80%.
In combined mode, I LOAD(MAX) is the per-phase maxi-
mum current, which is half the actual maximum load
current for the combined output.
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
?
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
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. The worst-case output sag voltage can
be determined by:
) 2 ? ? ? ? V OUT V IN T SW ? ? ? + t OFF ( M I N ) ?
(
L ? I LOAD(MAX)
? ? T SW ? t O F F ( MIN ) ?
? ? V IN ? V OUT ? ?
? ?
2 C OUT V OUT ? ?
?
improvements in MOSFET technology that are mak-
ing 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 SAG =
? ?
? ?
V IN ?
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
where t OFF(MIN) is the minimum off-time (see the
Electrical Characteristics table).
The amount of overshoot due to stored inductor energy
can be calculated as:
with every cycle at maximum load). Inductor values
lower than this grant no further size-reduction benefit.
The optimum operating point is usually found
between 20% and 50% ripple current.
V SOAR
≈
( ? I LOAD ( MAX ) ) 2 L
N PH 2 C OUT V OUT
Inductor Selection
The per-phase switching frequency and operating point
(% ripple current or LIR) determine the inductor value
as follows:
where N PH is the number of active phases per output.
N PH is 1 for separate mode, and N PH is 2 for com-
bined-mode operation.
28
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| MAX17008GTI+ | 功能描述:电压模式 PWM 控制器 QPWM Graphics Core Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17008GTI+T | 功能描述:电压模式 PWM 控制器 QPWM Graphics Core Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17009GTL+ | 功能描述:其他电源管理 AMD Dual-Phase CPU Controller RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
| MAX17009GTL+T | 功能描述:其他电源管理 AMD Dual-Phase CPU Controller RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
| MAX1700EEE | 功能描述:直流/直流开关转换器 1-3 Cell 1A Step-Up DC/DC Converters RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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