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參數(shù)資料
| 型號： | MAX1855 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 數(shù)字信號處理 |
| 英文描述： | Fixed-Point Digital Signal Processor 352-FC/CSP 0 to 0 |
| 中文描述： | 高速、數(shù)字可調(diào)、同步降壓型控制器，集成電壓定位電路 |
| 文件頁數(shù)： | 14/33頁 |
| 文件大小： | 840K |
| 代理商： | MAX1855 |
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M
High-Speed, Adjustable, Synchronous Step-Down
Controllers with Integrated Voltage Positioning
14
______________________________________________________________________________________
_______________Detailed Description
The MAX1716/MAX1854/MAX1855 buck controllers are
targeted for low-voltage, high-current CPU core power
supplies for notebook computers that typically require
18A (or greater) load steps. The proprietary Quick-
PWM pulse-width modulator in the converter is specifi-
cally designed for handling fast load steps while
maintaining a relatively constant operating frequency
and inductor operating point over a wide range of input
voltages. The Quick-PWM architecture circumvents the
poor load-transient timing problems of fixed-frequency
current-mode PWMs while also avoiding the problems
caused by widely varying switching frequencies in con-
ventional constant on-time and constant off-time PFM
schemes.
+5V Bias Supply (V
CC
and V
DD
)
The MAX1716/MAX1854/MAX1855 require an external
+5V bias supply in addition to the battery. Typically this
+5V bias supply is the notebook
’
s 95% efficient +5V
system supply. Keeping the bias supply external to the
IC improves efficiency and eliminates the cost associat-
ed with the +5V linear regulator that would otherwise be
needed to supply the PWM circuit and gate drivers. If
stand-alone capability is needed, the +5V supply can
be generated with an external linear regulator.
The +5V bias supply powers V
CC
(PWM controller) and
V
DD
(gate-drive power). The maximum current is:
I
BIAS
= I
CC
+
×
(Q
G1
+ Q
G2
) = 10mA to 40mA (typ)
where I
CC
is 700μA (typ),
is the switching frequency,
and Q
G1
and Q
G2
are the MOSFET data sheet total
gate-charge specification limits at V
GS
= 5V.
The battery input (V+) and +5V bias inputs (V
CC
and
V
DD
) can be connected together if the input source is a
fixed 4.5V to 5.5V supply. If the +5V bias supply is
powered up prior to the battery supply, the enable sig-
nal (
SHDN
) must be delayed until the battery voltage is
present to ensure startup.
Free-Running, Constant-On-Time PWM
Controller with Input Feed-Forward
The Quick-PWM control architecture is a constant-on-
time, current-mode type with voltage feed-forward
(Figure 2). This architecture relies on the output ripple
voltage to provide the PWM ramp signal. Thus, the out-
put filter capacitor
’
s ESR acts as a feedback resistor.
The control algorithm is simple: the high-side switch on-
time is determined solely by a one-shot whose period is
inversely proportional to input voltage and directly pro-
portional to output voltage (see
On-Time One-Shot
).
Another one-shot sets a minimum off-time (400ns typ).
The on-time one-shot is triggered if the error compara-
MANUFACTURER
MOSFETs
Fairchild Semiconductor
International Rectifier
Siliconix
CAPACITORS
Kemet
Panasonic
PHONE (COUNTRY CODE)
WEBSITE
(1) 888-522-5372
(1) 310-322-3331
(1) 203-268-6261
www.fairchildsemi.com
www.irf.com
www.vishay.com
(1) 408-986-0424
(1) 847-468-5624
www.kemet.com
www.panasonic.com
Sanyo
(65) 281-3226 (Singapore)
(1) 408-749-9714
www.secc.co.jp
Taiyo Yuden
(03) 3667-3408 (Japan)
(1) 408-573-4150
www.t-yuden.com
TDK
INDUCTORS
Coilcraft
Coiltronics
Sumida
(1) 847-390-4373
www.tdk.com
(1) 800-322-2645
(1) 561-752-5000
(1) 408-982-9660
www.coilcraft.com
www.coiltronics.com
www.sumida.com
Sumitomo
(1) 408-451-8441 (USA)
81 75 961-3141 (Japan)
www.ssmc.co.jp
Table 2. Component Suppliers
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1854EEG | High-Speed, Adjustable, Synchronous Step-Down Controllers with Integrated Voltage Positioning |
| 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 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1855EEG | 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1855EEG+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1855EEG-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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1855EVKIT | 功能描述:DC/DC 開關(guān)控制器 Evaluation Kit for the MAX1716 MAX1854 MAX1855 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1856EUB | 功能描述:電信線路管理 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
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