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參數(shù)資料
| 型號： | MAX1549ETL+T |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Dual, Interleaved, Fixed-Frequency Step-Down Controller with a Dynamically Adjustable Output |
| 中文描述： | 3 A DUAL SWITCHING CONTROLLER, 450 kHz SWITCHING FREQ-MAX, QCC40 |
| 封裝： | 6 X 6 MM, 0.80 MM HEIGHT, MO-220WJJD-2, TQFN-40 |
| 文件頁數(shù)： | 20/35頁 |
| 文件大?。?/td> | 933K |
| 代理商： | MAX1549ETL+T |
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Setting the Peak Current Limit
The minimum current-limit threshold must be great
enough to support the maximum load current when the
current limit is at the minimum tolerance value. The
peak inductor current occurs at ILOAD(MAX) plus 1/2 the
ripple current; therefore:
where ILIMIT_ equals the minimum current-limit thresh-
old voltage divided by the current-sense resistance
(RSENSE). For the 70mV default setting, the minimum
current-limit threshold is 65mV.
Connect ILIM_ to VCC for a default 70mV current-limit
threshold. In adjustable mode, the current-limit thresh-
old is precisely 1/10th the voltage seen at ILIM_. For an
adjustable threshold, connect a resistive divider from
REF to analog ground (GND) with ILIM_ connected to
the center tap. The external 500mV to 2V adjustment
range corresponds to a 50mV to 200mV current-limit
threshold. When adjusting the current limit, use 1% tol-
10A to prevent significant inaccuracy in the current-
limit tolerance.
The current-sense method (Figure 8) and magnitude
determine the achievable current-limit accuracy and
power loss. Typically, higher current-sense limits provide
more noise immunity, but also dissipate more power.
Most applications employ a current-limit threshold
(VLIMIT) of 50mV to 100mV, so the sense resistor can be
determined by:
For the best current-sense accuracy and overcurrent
protection, use a 1% tolerance current-sense resistor
between the inductor and output as shown in Figure
8A. This configuration constantly monitors the inductor
current, allowing accurate current-limit protection.
Alternately, high-power applications that do not require
highly accurate current-limit protection can reduce the
overall power dissipation by connecting a series RC
circuit across the inductor (Figure 8B) with an equiva-
lent time constant:
where RDCR is the inductor’s series DC resistance. In
this configuration, the current-sense resistance equals
the inductor’s DC resistance (RSENSE = RDCR). Use the
worst-case inductance and RDCR values provided by the
inductor manufacturer, adding some margin for the
inductance drop over temperature and load.
Output Capacitor Selection
The output-filter capacitor must have low enough equiv-
alent series resistance (ESR) to meet output ripple and
load-transient requirements, yet have high enough ESR
to satisfy stability requirements.
For processor core voltage converters and other appli-
cations where the output is subject to severe load tran-
sients, the output capacitor’s size depends on how
much ESR is needed to prevent the output from dip-
ping too low under a load transient. Ignoring the sag
due to finite capacitance:
R
V
I
ESR
STEP
LOAD MAX
()
≤
L
R
CR
DCR
EQL
=×
R
V
I
SENSE
LIMIT
=
II
I
LIR
LIMIT
LOAD MAX
()
>+
2
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
______________________________________________________________________________________
27
MAX1549
COUT
INPUT (VIN)
L
CIN
RSENSE
DL
NH
NL
DH_
LX_
DL_
PGND
CSH_
CSL_
A) OUTPUT SERIES RESISTOR SENSING
MAX1549
COUT
INPUT (VIN)
CIN
DL
NH
NL
DH_
LX_
DL_
PGND
CSH_
CSL_
B) LOSSLESS INDUCTOR SENSING
INDUCTOR
REQL
CEQL
RBIAS = REQL
Figure 8. Current-Sense Configurations
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參數(shù)描述 |
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| MAX1549EVKIT | 功能描述:電源管理IC開發(fā)工具 RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| MAX154ACAG | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| MAX154ACAG+ | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| MAX154ACAG+T | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| MAX154ACAG-T | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
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