參數(shù)資料
型號(hào)： MAX1854EEG
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： High-Speed, Adjustable, Synchronous Step-Down Controllers with Integrated Voltage Positioning
中文描述： SWITCHING CONTROLLER, 550 kHz SWITCHING FREQ-MAX, PDSO24
封裝： 0.150 INCH, 0.025 INCH PITCH, QSOP-24
文件頁(yè)數(shù)： 26/33頁(yè)
文件大?。?/td> 840K
代理商： MAX1854EEG
M
High-Speed, Adjustable, Synchronous Step-Down
Controllers with Integrated Voltage Positioning
26
______________________________________________________________________________________
________________Applications Issues
Voltage Positioning and
Effective Efficiency
Powering new mobile processors requires careful
attention to detail to reduce cost, size, and power dissi-
pation. As CPUs became more power hungry, it was
recognized that even the fastest DC-DC converters
were inadequate to handle the transient power require-
ments. After a load transient, the output instantly
changes by ESR
COUT
×
I
LOAD
. Conventional DC-DC
converters respond by regulating the output voltage
back to its nominal state after the load transient occurs
(Figure 7). However, the CPU only requires that the out-
put voltage remain above a specified minimum value.
Dynamically positioning the output voltage to this lower
limit allows the use of fewer output capacitors and
reduces power consumption under load.
For a conventional (nonvoltage-positioned) circuit, the
total voltage change is:
V
P-P1
= 2
×
(ESR
COUT
×
I
LOAD
) + V
SAG
+ V
SOAR
where V
SAG
and V
SOAR
are defined in Figure 8. Setting
the converter to regulate at a lower voltage when under
load allows a larger voltage step when the output cur-
rent suddenly decreases (Figure 7). So the total voltage
change for a voltage positioned circuit is:
V
P-P2
= (ESR
COUT
×
I
LOAD
) + V
SAG
+ V
SOAR
where V
SAG
and V
SOAR
are defined in the
Design
Procedure.
Since the amplitudes are the same for both
circuits (V
P-P1
= V
P-P2
), the voltage-positioned circuit
requires only twice the ESR. Since the ESR specifica-
tion is achieved by paralleling several capacitors, fewer
units are needed for the voltage-positioned circuit.
An additional benefit of voltage positioning is reduced
power consumption at high load currents. Because the
output voltage is lower under load, the CPU draws less
current. The result is lower power dissipation in the
CPU, although some extra power is dissipated in
R
SENSE
. For a nominal 1.6V, 18A output (R
LOAD
=
89m
), reducing the output voltage 2.9% gives an out-
put voltage of 1.55V and an output current of 17.44A.
Given these values, CPU power consumption is
reduced from 28.8W to 27.03W. The additional power
consumption of R
SENSE
is:
2.5m
×
(17.44A)
2
= 0.76W
and the overall power savings is as follows:
28.8W - (27.03W + 0.76W) = 1.01W
In effect, 1.8W of CPU dissipation is saved and the
power supply dissipates much of the savings, but both
the net savings and the transfer of heat away from the
CPU are beneficial. Effective efficiency is defined as
the efficiency required of a nonvoltage-positioned cir-
cuit to equal the total dissipation of a voltage-posi-
tioned circuit for a given CPU operating condition.
Calculate effective efficiency as follows:
1) Start with the efficiency data for the positioned
circuit (V
IN
, I
IN
, V
OUT
, I
OUT
).
2) Model the load resistance for each data point:
I
LOAD
CAPACITOR SOAR
(ENERGY IN L
TRANSFERRED TO C
OUT
)
CAPACITIVE SAG
(dV/dt = I
OUT
/C
OUT
)
RECOVERY
ESR STEP-DOWN
AND STEP-UP
(I
STEP
X ESR)
V
OUT
Figure 8. Transient-Response Regions
B
1.6V
1.6V
A
A. CONVENTIONAL CONVERTER (50mV/div)
B. VOLTAGE POSITIONED OUTPUT (50mV/div)
VOLTAGE POSITIONING THE OUTPUT
MAX1716-Figure 07
Figure 7. Voltage Positioning the Output
相關(guān)PDF資料
PDF描述
MAX1855EEG Replaced by TMS320C6202B : Fixed-Point Digital Signal Processor 352-FCBGA
MAX1854 High-Speed, Adjustable, Synchronous Step-Down Controllers with Integrated Voltage Positioning
MAX1857EUA47 500mA, Low-Dropout, Ripple-Rejecting LDO in MAX
MAX1857 Replaced by TMS320C6202B : Fixed-Point Digital Signal Processor 352-FCBGA
MAX1858 Dual 180∑ Out-of-Phase Buck Controllers with Sequencing/Prebias Startup and POR
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1854EEG/GG8 功能描述:DC/DC 開(kāi)關(guān)控制器 High-Speed Adjustable Synchronous Step-Down Controllers with Integrated Voltage Positioning RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
MAX1854EEG+ 制造商:Maxim Integrated Products 功能描述:HIGH-SPEED,DIGITALLY ADJUSTABLE SYNCHRONOUS STEPDOWN CONTROL - Rail/Tube
MAX1854EEG+T 制造商: 功能描述: 制造商:undefined 功能描述:
MAX1854EEGT 制造商: 功能描述:
MAX1854EEG-T 功能描述:DC/DC 開(kāi)關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*