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
文件頁數(shù)： 25/33頁
文件大小： 840K
代理商： MAX1854EEG
M
High-Speed, Adjustable, Synchronous Step-Down
Controllers with Integrated Voltage Positioning
______________________________________________________________________________________
25
the complete expression for the voltage-positioned out-
put depends only upon the value of the current-sense
resistor and the load current:
V
OUT
≈
V
OUT(PROG)
(1 - A
VPS
I
LOAD
R
SENSE
)
Some applications require the addition of a positive off-
set to the output voltage to ensure that it remains within
the load specifications. The positive offset may be gen-
erated by connecting a resistive divider from REF to
VPS to CS (Figure 6a). Set R1 to 1k
, and use the fol-
lowing equation to calculate R3:
where V
REF
is typically 2.0V, and V
OFFSET
is the
required positive offset voltage. When attenuating the
voltage-positioning signal, replace R1 with the parallel
combination of R1 and R2 (R1//R2), where R2 is the
attenuation resistor (Figure 6b).
After a load transient, the output instantly changes by
ESR
COUT
×
I
LOAD
. Setting the load-dependent volt-
age position to match this initial load step allows the
output voltage to change by ESR
COUT
×
I
LOAD
and
stay there as long as the load remains unchanged (see
Voltage Positioning and Effective Efficiency
). To set the
voltage position equal to the initial voltage drop gener-
ated by the output capacitor
’
s ESR, select R
SENSE
=
ESR
COUT
/ (V
OUT(PROG)
×
A
VPS
).
For applications using a larger current-sense resistor,
adjust V
VPS
by connecting a resistive divider from CS
to VPS to PGND (Figure 6b). Set R1 to 1k
, and use the
following equation to calculate R2:
(
The MAX1716/MAX1854/MAX1855 voltage-positioning
circuit has several advantages over older circuits,
which added a fixed voltage offset on the sense point
and used a low-value resistor in series with the output.
The new circuit can use the same current-sense resis-
tor for both voltage positioning and current-limit detec-
tion. This simultaneously provides accurate current
limiting and voltage positioning. Since the new circuit
adjusts the output voltage within the control loop, the
voltage-positioning signal may be internally amplified.
The additional gain allows the use of low-value current-
sense resistors, so the power dissipated in this sense
resistor is significantly lower than a single resistor con-
nected directly in series with the output.
Voltage-Positioning Compensation (CC)
The voltage-positioning compensation capacitor filters
the amplified VPS signal, allowing the user to adjust the
dynamics of the voltage-positioning loop. The imped-
ance at this node is approximately 200k
, so the pole
provided by this node can be approximated by 1 / (2
×
π ×
RC). The response time is set with a 47pF to
1000pF capacitor from CC to GND.
R
R
ESR
A
R
)
ESR
COUT
SENSE
VPS OUT PROG
COUT
2
1
=
R
R
V
V
REF VPS OUT PROG
OFFSET
3
1
1
=
(
)
MAX1716
MAX1854
MAX1855
DL
CS
VPS
PGND
N
R1
R
SENSE
a) SCALED VOLTAGE POSITION SIGNAL
b) POSITIVE NO-LOAD VOLTAGE POSITIONING
R2
MAX1716
MAX1854
MAX1855
REF
VPS
CS
DL
PGND
R3
Q2
R1
R
SENSE
C
REF
0.22
μ
F
Figure 6. Voltage-Positioning Configurations
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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 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(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
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