參數(shù)資料
型號(hào)： MAX770MJA
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers
中文描述： SWITCHING CONTROLLER, 300 kHz SWITCHING FREQ-MAX, CDIP8
封裝： CERDIP-8
文件頁(yè)數(shù)： 12/20頁(yè)
文件大?。?/td> 204K
代理商： MAX770MJA
M
turned on, it stays on until either 1) the maximum on-
time one-shot turns it off (typically 16μs later), or 2) the
switch current reaches the peak current limit set by the
current-sense resistor.
To increase light-load efficiency, the current limit for the
first two pulses is set to one-half the peak current limit.
If those pulses bring the output voltage into regulation,
the error comparator holds the MOSFET off and the
current limit remains at one-half the peak current limit. If
the output voltage is still out of regulation after two
pulses, the current limit for the next pulse is raised to
the peak current limit set by the external sense resistor
(see inductor current waveforms in the Typical
Operating Characteristics).
The MAX770–MAX773 switching frequency is variable
(depending on load current and input voltage), causing
variable switching noise. However, the subharmonic
noise generated does not exceed the peak current limit
times the filter capacitor equivalent series resistance
(ESR). For example, when generating a 12V output at
500mA from a 5V input, only 180mV of output ripple
occurs using the circuit of Figure 2b.
Low-Voltage Start-Up Oscillator
The MAX770/MAX771/MAX772 feature a low input volt-
age start-up oscillator that guarantees start-up with no
load down to 2V when operating in bootstrapped mode
and using internal feedback resistors. At these low volt-
ages, the supply voltage is not large enough for proper
error-comparator operation and internal biasing. The
start-up oscillator has a fixed 50% duty cycle and the
MAX770/MAX771/MAX772 disregard the error-com-
parator output when the supply voltage is less than
2.5V. Above 2.5V, the error-comparator and normal one-
shot timing circuitry are used. The low voltage start-up
circuitry is disabled if non-bootstrapped mode is select-
ed (FB is not tied to ground).
The MAX773 does not provide the low-voltage 50%
duty-cycle oscillator. Its minimum start-up voltage is 3V
for all modes.
External T ransistor
An N-FET power switch is recommended for the
MAX770/MAX771/MAX772.
The MAX773 can drive either an N-channel MOSFET
(N-FET) or an NPN because it provides two separate
5V /12V /15V or Adjustable, High-Efficiency,
Low I
Q
, Step-Up DC-DC Controllers
12
______________________________________________________________________________________
GND
MAX773
C3
0.1
μ
F
v+
EXTL
CS
V5
8
5
7
V15
V12
LBO
REF
LBI
SHDN
4
12
11
2
14
1
9
R
SENSE
1.0
C4
100
μ
F
D1
MUR115
EXTH
13
3
L1
250
μ
H
V
OUT
= 100V
@ 10mA
SGND
N
Si9420DY
10
C1
47
μ
F
FB
6
R2
732k (1%)
R1
11.3k (1%)
R
SHUNT
3k
C2
0.1
μ
F
V
IN
= 24V TO 28V
OUT
V
REF
R2 = (R1)
(
V
)
V
REF
= 1.5V
MAX773
R
SHUNT
C2
0.1
μ
F
SGND
6V (typ)
V+
V
IN
R
SHUNT =
V
IN (MIN)
- V
SHUNT
(
MAX
)
I
SHUNT
*
*
SEE TEXT FOR I
SHUNT
CALCULATION
3
10
Figure 3e. 100V Output, Shunt Regulator, N-Channel Power
MOSFET
Figure 4. MAX773 Shunt Regulator
相關(guān)PDF資料
PDF描述
MAX771CPA 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers
MAX771CSA 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers
MAX771EPA 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers
MAX771ESA 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers
MAX772CPA 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX771C/D 功能描述:DC/DC 開關(guān)控制器 5V/12V/15V or Adjustable High-Efficiency Low-IQ Step-Up DC-DC Controllers 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(fēng)格: 封裝 / 箱體:CPAK
MAX771C/D DIE 制造商:Maxim Integrated Products 功能描述:
MAX771C/D+ 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(fēng)格: 封裝 / 箱體:CPAK
MAX771CPA 功能描述:DC/DC 開關(guān)控制器 5/12/15/AdjV Step Up DC/DC Controller 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(fēng)格: 封裝 / 箱體:CPAK
MAX771CPA+ 功能描述:DC/DC 開關(guān)控制器 5/12/15/AdjV Step Up DC/DC Controller 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(fēng)格: 封裝 / 箱體:CPAK
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