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參數(shù)資料
| 型號： | MAX1816 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 數(shù)字信號處理 |
| 英文描述： | Replaced by TMS320VC5506 : Digital Signal Processors 144-LQFP |
| 中文描述： | 雙路、降壓型控制器及線性穩(wěn)壓控制器，用于筆記本電腦 |
| 文件頁數(shù)： | 40/49頁 |
| 文件大小： | 983K |
| 代理商： | MAX1816 |
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M
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
40
______________________________________________________________________________________
BUCK1 Stability Considerations
BUCK1 is fundamentally different from previous Quick-
PWM controllers in two respects: it uses a current-sense
amplifier to obtain the current feedback signal (ramp),
and it uses differential remote sense to compensate for
voltage drops along the high-current path. The regulator
adds the differential remote-sense signal to the current-
feedback signal to correct the output voltage. As long
as the amplitude of the resulting signal is greater than
1% of the output voltage, the regulator remains stable.
Stability can be determined by comparing the zero
formed with the current-sense feedback network to the
switching frequency.
The boundary condition of stability is given by the fol-
lowing expression:
f
Z
≤
where C
OUT1
is the local output capacitance (Figure 1),
C
REMOTE
is the remote output capacitance, R
LOCAL
is
the ESR of the local capacitors, R
REMOTE
is the ESR of
the remote capacitors, and R
DROOP
is the effective
voltage-positioning resistance, which is determined by
the voltage-positioning gain A
VPS
and current-sense
resistor R
SENSE
:
R
DROOP
= A
VPS
x R
SENSE
Like previous Quick-PWM controllers, larger values of
ESR and sense resistance increase stability. The volt-
age-positioning gain A
VPS
effectively increases the
sense resistance, which further enhances stability.
The RC time constants of the local and remote capaci-
tors affect the stability criteria. These two time con-
stants are defined as follows:
τ
LOCAL
= (R
DROOP
+ R
LOCAL
+ R
PCB_TRACE
) x C
OUT1
τ
REMOTE
= (R
DROOP
+ R
REMOTE
) x C
REMOTE
where R
PCB
_
TRACE
is the PC board trace resistance
shown in Figure 1.
When the local capacitance time constant is either
much greater or much smaller than that of the remote
capacitance, the stability criteria is:
In applications where these two time constants are
approximately equal, the criteria for stable operation
reduces to:
(
The standard application circuit (Figure 1) operating at
300kHz easily achieves stable operation because the
time constant of the local capacitors is much greater
than that of the remote capacitors.
In this example, C
OUT1
= 990μF, R
LOCAL
= 3.3m
,
C
REMOTE
= 10μF, R
REMOTE
= 5m
, and R
DROOP
= 2 x
1m
= 2m
:
(
When voltage positioning is not used (A
VPS
= 0) and the
ESR of the output capacitors alone cannot meet the sta-
bility requirement, the current feedback signal must be
generated from a different source. The current ramp sig-
nal at CS1+ and the output voltage must be summed at
the FBS input. For stable operation, a 3.3μF feed-for-
ward capacitor is added from the CS1+ input to FBS
and a 10
resistor is inserted from the remote load to
FBS forming an RC filter (Figure 12). The cutoff frequen-
cy of the RC filter should be approximately an order of
magnitude lower than the regulator
’
s switching frequen-
cy to prevent sluggish transient response. To avoid
input-bias current-induced offset errors, the resistor
should be less than 20
.
2
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
5 32
R
R
C
f
and
R
(
R
C
f
DROOP
LOCAL
OUT
SW
DROOP
REMOTE
REMOTE
SW
+
)
×
≥
×
+
)
×
≥
×
1
1
2
1
2
R
C
(
C
R
C
R
C
f
DROOP
OUT
REMOTE
LOCAL
1
OUT
REMOTE
REMOTE
SW
×
+
)
+
×
+
×
≥
×
1
1
2
f
R
R
C
(
C
C
R
C
Z
DROOP
OUT
REMOTE
LOCAL
OUT
REMOTE
REMOTE
≈
×
×
×
+
)
+
×
+
1
2
1
1
π
f
SW
π
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PDF描述 |
|---|---|
| MAX1816ETM | Replaced by TMS320VC5506 : Digital Signal Processors 144-LQFP |
| MAX199AEWI | Fixed-Point Digital Signal Processor 532-FCBGA |
| MAX199AMYI | Circular Connector; No. of Contacts:18; Series:MS27505; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:15; Circular Contact Gender:Socket; Circular Shell Style:Box Mount Receptacle RoHS Compliant: No |
| MAX199ACAI | Multi-Range (【4V, 【2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface |
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1816ETM | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1816ETM+ | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1816ETM+T | 功能描述:DC/DC 開關控制器 NULL RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1816ETM-T | 功能描述:DC/DC 開關控制器 NULL RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1816XR31+ | 制造商:Maxim Integrated Products 功能描述: |
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