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| 型號： | MAX1816ETM |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Replaced by TMS320VC5506 : Digital Signal Processors 144-LQFP |
| 中文描述： | DUAL SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, CQCC48 |
| 封裝： | 7 X 7 MM, 0.80 MM HEIGHT, THIN, QFN-48 |
| 文件頁數(shù)： | 41/49頁 |
| 文件大?。?/td> | 983K |
| 代理商： | MAX1816ETM |
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M
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
______________________________________________________________________________________
41
For nonvoltage-positioned applications using a feed-
forward circuit, the RC time constants of the local and
remote capacitors are defined as:
τ
LOCAL
= (R
SENSE
+ R
LOCAL
) x C
OUT1
τ
REMOTE
= (R
SENSE
+ R
REMOTE
+ R
PCB_TRACE
)
x C
REMOTE
The new stability criteria for nonvoltage-positioned
applications using feed forward becomes:
(
1
for
τ
LOCAL
much greater or much smaller than
τ
REMOTE
, and
R
R
C
SENSE
LOCAL
+
when
τ
LOCAL
and
τ
REMOTE
are approximately equal.
If the voltage-positioning gain in the standard applica-
tion circuit (Figure 1) is set to zero and the feed-forward
compensation circuit shown in Figure 12 is used, stable
operation can still be easily achieved.
In this example, C
OUT1
= 990μF, R
LOCAL
= 3.3m
,
C
REMOTE
= 10μF, R
REMOTE
= 5m
, R
SENSE
= 1m
,
and R
PCB
_
TRACE
= 2m
, and the local time constant is
much greater than the remote time constant.
Therefore:
Unstable operation manifests itself in two related but
distinctly different ways: double-pulsing and fast-feed-
back loop instability. Double-pulsing occurs due to
noise on the output or because the ESR is so low that
there is not enough voltage ramp in the output-voltage
signal. This
“
fools
”
the error comparator into triggering
a new cycle immediately after the 400ns minimum off-
time period has expired. Double-pulsing is more annoy-
ing than harmful, resulting in nothing worse than
increased output ripple. However, it can indicate the
possible presence of loop instability, which is caused
by insufficient current feedback signal.
Loop instability can result in oscillations at the output
after line or load perturbations that can trip the overvolt-
age protection latch or cause the output voltage to fall
below the tolerance limit. The easiest method for check-
ing stability is to apply a very fast zero-to-max load
transient and carefully observe the output-voltage rip-
ple envelope for overshoot and ringing. It can help to
simultaneously monitor the inductor current with an AC
current probe. Do not allow more than one cycle of
ringing after the initial step-response under/overshoot.
BUCK2 Stability Considerations
The stability criterion for BUCK2 is the same as previous
Quick-PWM controllers like the MAX1714. Stability is
determined by comparing the value of the ESR zero to
the switching frequency. The point of stability is given by
the following expression:
f
ESR
≤
For good phase margin, it is recommended to increase
the equivalent RC time constant by a factor of two. The
standard application circuit (Figure 1) operating at
390kHz with C
OUT
= 330μF and R
ESR
= 10m
, easily
meets this requirement.
f
where
f
R
C
SW
π
ESR
ESR
OUT
=
×
×
π
1
2
1
990
10
3 3
.
990
5
10
1
2 300
1 67
.
m
F
F
m
F
m
F
kHz
s
s
×
+
(
)
+
×
+
×
≥
≥
μ
μ
μ
μ
μ
μ
4 32
f
and
R
(
R
C
f
OUT
SW
SENSE
REMOTE
REMOTE
SW
(
)
×
≥
×
+
)
×
≥
×
1
1
2
1
2
R
C
C
R
C
R
C
f
SENSE
OUT
REMOTE
LOCAL
1
2
OUT
REMOTE
REMOTE
SW
×
+
)
+
×
+
×
≥
×
1
Figure 12. Output Feed Forward for Nonvoltage-Positioned
Applications
C
OUT
PC BOARD TRACE
RESISTANCE
R
SENSE
3.3
μ
F
10
PC BOARD TRACE
RESISTANCE
REMOTE
LOAD
CS1+
CS1-
FBS
GDS
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1816ETM+ | 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 |
| MAX1816ETM+T | 功能描述:DC/DC 開關(guān)控制器 NULL 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 |
| MAX1816ETM-T | 功能描述:DC/DC 開關(guān)控制器 NULL 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 |
| MAX1816XR31+ | 制造商:Maxim Integrated Products 功能描述: |
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