參數資料
型號: MAX1744
廠商: Maxim Integrated Products, Inc.
元件分類: 數字信號處理
英文描述: Replaced by TMS320C6410 : Digital Signal Processor 44-PLCC 0 to 70
中文描述: 高壓、降壓型DC-DC控制器,µMAX封裝
文件頁數: 9/14頁
文件大?。?/td> 256K
代理商: MAX1744
M
High-Voltage, Step-Down DC-DC
Controller in μMAX
_______________________________________________________________________________________
9
At light output loads, the inductor current is discontinu-
ous, causing the MAX1744/MAX1745 to operate at
lower frequencies, reducing the MOSFET gate drive
and switching losses. In discontinuous mode, under
most circumstances, the on-time will be the fixed mini-
mum on-time of 1μs. If the inductor value is small, or
the current-sense resistor large, the current limit will be
tripped before the minimum on-time, terminating the
on-time and thus setting the fixed on-time.
If the inductance is too large, or the output capacitance
high and equivalent series resistance (ESR) low, then
the MOSFET remains on longer than the minimum on-
time, until the output capacitor charges beyond the
error comparator
s (V
OUT
/ 1.25V)
8mV hysteresis,
causing the part to operate in hysteretic mode.
Operating in hysteretic mode results in lower frequency
operation. The transition to hysteretic mode occurs at
the critical output capacitor ESR:
ESR
CRITICAL
= (V
OUT
/ 1.25V)
8mV / I
RIPPLE
where I
RIPPLE
is the inductor ripple current, and can be
determined by:
I
RIPPLE
= (V
IN
- V
OUT
)
t
ON(MIN)
/ L
where t
ON(MIN)
is the minimum on-time (1μs) for mini-
mum on-time-control, or:
I
RIPPLE
= (V
OUT
)
t
OFF(MIN)
/ L
where t
OFF(MIN)
is the minimum off-time (2μs) for mini-
mum off-time-control.
REF
MINIMUM
OFF-TIME
ONE SHOT
Q TRIG
VL
LINEAR
REGULATOR
VH
LINEAR
REGULATOR
1.25
REFERENCE
(FB)
ERROR
COMPARATOR
OUT
3/5
SHDN
CS
100mV
+
Q
R
S
VL
SHDN
VH
EXT
IN
MINIMUM
ON-TIME
ONE SHOT
Q TRIG
( ) MAX1745 ONLY
- - - MAX1744 ONLY
Figure 2. Simplified Functional Diagram
相關PDF資料
PDF描述
MAX1745 High-Voltage, Step-Down DC-DC Controller in レMAX
MAX1744EUB Replaced by TMS320C6410 : Digital Signal Processor 40-PDIP 0 to 70
MAX1745EUB High-Voltage, Step-Down DC-DC Controller in レMAX
MAX1744AUB High-Voltage, Step-Down DC-DC Controller in レMAX
MAX1745AUB High-Voltage, Step-Down DC-DC Controller in レMAX
相關代理商/技術參數
參數描述
MAX1744AUB 功能描述:DC/DC 開關控制器 Step-Down DC/DC Controller 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 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK
MAX1744AUB/V+ 功能描述:DC/DC 開關控制器 Step-Down DC/DC Controller 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 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK
MAX1744AUB/V+T 功能描述:DC/DC 開關控制器 Step-Down DC/DC Controller 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 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK
MAX1744AUB+ 功能描述:DC/DC 開關控制器 Step-Down DC/DC Controller 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 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK
MAX1744AUB+T 功能描述:DC/DC 開關控制器 Step-Down DC/DC Controller 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 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK