參數(shù)資料
型號(hào)： MAX1887
廠商： Maxim Integrated Products, Inc.
英文描述： Quick-PWM Slave Controllers for Multiphase, Step-Down
中文描述： Quick-PWM從控制器，用于多相、降壓型電源
文件頁(yè)數(shù)： 26/33頁(yè)
文件大?。?/td> 1018K
代理商： MAX1887
M
50mV x 21.3A = 1.06W,
which results in an overall power savings of:
35.2W - (33.03W + 1.06W) = 1.10W.
In effect, 2.2W of CPU dissipation is saved and the
power supply dissipates much of the savings, but both
the net savings and the transfer of dissipation away
from the hot CPU are beneficial. Effective efficiency is
defined as the efficiency required of a nonvoltage-posi-
tioned circuit to equal the total dissipation of a voltage-
positioned circuit for a given CPU operating condition.
Calculate effective efficiency as follows:
1) Start with the efficiency data for the positioned cir-
cuit (V
IN
, I
IN
, V
OUT
, I
OUT
).
2) Model the load resistance for each data point:
R
LOAD
= V
OUT
/ I
OUT
3) Calculate the output current that would exist for each
R
LOAD
data point in a nonpositioned application:
I
NP
= V
NP
/ R
LOAD
where V
NP
= 1.6V (in this example).
4) Calculate effective efficiency as:
Effective efficiency = (V
NP
I
NP
) / (V
IN
I
IN
) = cal-
culated nonpositioned power output divided by the
measured voltage-positioned power input.
5) Plot the efficiency data point at the nonpositioned
current, I
NP
.
The effective efficiency of voltage-positioned circuits is
shown in the
Typical Operating Characteristics
.
One-Stage (Battery Input) Versus
Two-Stage (5V Input) Applications
The MAX1887/MAX1897 can be used with a direct bat-
tery connection (one stage) or can obtain power from a
regulated 5V supply (two-stage). Each approach has
advantages, and careful consideration should go into
the selection of the final design.
The one-stage approach offers smaller total inductor
size and fewer capacitors overall due to the reduced
demands on the 5V supply. Due to the high input volt-
age, the one-stage approach requires lower DC input
currents, reducing input connection/bus requirements
and power dissipation due to input resistance. The
transient response of the single stage is better due to
the ability to ramp the inductor current faster. The total
efficiency of a single stage is better than the two-stage
approach.
The two-stage approach allows flexible placement due
to smaller circuit size and reduced local power dissipa-
tion. The power supply can be placed closer to the
CPU for better regulation and lower I
2
R losses from PC
board traces. Although the two-stage design has slow-
er transient response than the single stage, this can be
offset by the use of a voltage-positioned converter.
Quick-PWM Slave Controllers for
Multiphase, Step-Down Supplies
26
______________________________________________________________________________________
V
OUT
ESR VOLTAGE STEP
(I
STEP
x R
ESR
)
CAPACITIVE SOAR
(dV/dt = I
OUT
/C
OUT
)
RECOVERY
CAPACITIVE SAG
(dV/dt = I
OUT
/C
OUT
)
I
LOAD
Figure 8. Transient Response Regions
B
1.4V
1.4V
A
A. CONVENTIONAL CONVERTER (50mV/div)
B. VOLTAGE-POSITIONED OUTPUT (50mV/div)
VOLTAGE POSITIONING THE OUTPUT
Figure 7. Voltage Positioning the Output
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1887EEE 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1887EEE+ 功能描述:電流型 PWM 控制器 CDMA Cellular/PCS System Power Supplies RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1887EEE+T 功能描述:電流型 PWM 控制器 CDMA Cellular/PCS System Power Supplies RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1887EEE-T 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1888EUA 功能描述:其他電源管理 RoHS:否 制造商:Texas Instruments 輸出電壓范圍: 輸出電流:4 mA 輸入電壓范圍:3 V to 3.6 V 輸入電流: 功率耗散: 工作溫度范圍:- 40 C to + 110 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-48 封裝:Reel
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