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參數(shù)資料
| 型號： | MAX1856 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 數(shù)字信號處理 |
| 英文描述： | Replaced by TMS320C6202B : Fixed-Point Digital Signal Processor 352-FCBGA |
| 中文描述： | 寬輸入范圍、可同步的、PWM SLIC電源 |
| 文件頁數(shù)： | 8/18頁 |
| 文件大?。?/td> | 594K |
| 代理商： | MAX1856 |
M
Detailed Description
The MAX1856 current-mode PWM controller uses an
inverting flyback configuration that is ideal for generat-
ing the high negative voltages required for SLIC power
supplies. Optimum conversion efficiency is maintained
over a wide range of loads by employing both PWM
operation and Maxim
’
s proprietary Idle Mode control to
minimize operating current at light loads. Other features
include shutdown, adjustable internal operating fre-
quency or synchronization to an external clock, soft-
start, adjustable current limit, and a wide (3V to 28V)
input range.
PWM Controller
The heart of the MAX1856 current-mode PWM con-
troller is a BiCMOS multi-input comparator that simulta-
neously processes the output-error signal, the
current-sense signal, and a slope-compensation ramp
(Figure 2). The main PWM comparator is direct sum-
ming, lacking a traditional error amplifier and its associ-
ated phase shift. The direct-summing configuration
approaches ideal cycle-by-cycle control over the out-
put voltage since there is no conventional error amplifi-
er in the feedback path.
In PWM mode, the controller uses fixed-frequency, cur-
rent-mode operation where the duty ratio is set by the
input-to-output voltage ratio and the transformer
’
s turn
ratio. The current-mode feedback loop regulates peak
inductor current as a function of the output error signal.
At light loads, the controller enters Idle Mode. During
Idle Mode, switching pulses are provided only as nec-
essary to supply the load, and operating current is min-
imized to provide the best light-load efficiency. The
minimum-current comparator threshold is 15mV, or
15% of the full-load value (I
MAX
) of 100mV. When the
controller is synchronized to an external clock, Idle
Mode occurs only at very light loads.
Wide Input Range, Synchronizable,
PWM SLIC Power Supply
8
_______________________________________________________________________________________
Pin Description
PIN
NAME
FUNCTION
1
LDO
5V Linear Regulator Output. The regulator powers all of the internal circuitry, including the EXT gate
driver. Bypass LDO to GND with a 1μF or greater ceramic capacitor.
2
FREQ
Oscillator Frequency Set Input. A resistor from FREQ to GND sets the oscillator from 100kHz (R
OSC
=
500k
) to 500kHz (R
OSC
= 100k
): f
OSC
= 50M
-kHz / R
OSC
. The MAX1856 still requires R
OSC
when
an external clock is connected to SYNC/
SHDN
.
3
GND
Analog Ground
4
REF
1.25V Reference Output. REF can source up to 400μA. Bypass to GND with a 2.2μF ceramic capacitor.
5
FB
Feedback Input. The feedback voltage threshold is 0.
6
CS
Positive Current-Sense Input. Connect a current-sense resistor (R
CS
) between CS and PGND.
7
PGND
Power Ground
8
EXT
External MOSFET Gate-Driver Output. EXT swings from LDO to PGND.
9
V
CC
Input Supply to the Linear Regulator. V
CC
accepts inputs up to 28V. Bypass to PGND with a 1μF
ceramic capacitor.
10
SYNC/
SHDN
Shutdown Control and Synchronization Input. There are three operating modes:
SYNC/
SHDN
low: shutdown mode
SYNC/
SHDN
high: the DC-to-DC controller operates with the oscillator frequency set at FREQ by
R
OSC
SYNC/
SHDN
clocked: the DC-to-DC controller operates with the oscillator frequency set by the SYNC
clock input. The conversion cycles initiate on the rising edge of the input clock signal. However, the
MAX1856 still requires R
OSC
when SYNC/
SHDN
is externally clocked.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1856EUB | Replaced by TMS320C6202B : Fixed-Point Digital Signal Processor 352-FCBGA 0 to 0 |
| MAX1864 | Fixed-Point Digital Signal Processor 352-FCBGA |
| MAX1864-MAX1865 | Fixed-Point Digital Signal Processor 384-FC/CSP |
| MAX1865 | Fixed-Point Digital Signal Processor 352-FCBGA |
| MAX1864UEEE | xDSL/Cable Modem Triple/Quintuple Output Power Supplies |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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(fēng)格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
| MAX1856EUB+ | 功能描述:電信線路管理 IC Synchronizable PWM SLIC Power Supply 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(fēng)格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
| MAX1856EUB+T | 功能描述:電信線路管理 IC Synchronizable PWM SLIC Power Supply 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(fēng)格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
| MAX1856EUB-T | 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(fēng)格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
| MAX1856EVKIT | 功能描述:電源管理IC開發(fā)工具 Evaluation Kit for the MAX1856 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 |
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