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參數(shù)資料
| 型號： | MAX772CSA |
| 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, PDSO8 |
| 封裝： | SO-8 |
| 文件頁數(shù)： | 18/20頁 |
| 文件大?。?/td> | 204K |
| 代理商： | MAX772CSA |
M
Smaller capacitors are acceptable for light loads or in
applications that can tolerate higher output ripple.
Since the output filter capacitor’s ESR affects efficien-
cy, use low-ESR capacitors for best performance. The
smallest low-ESR surface-mount tantalum capacitors
currently available are the Sprague 595D series. Sanyo
OS-CON organic semiconductor through-hole capaci-
tors and the Nichicon PL series also exhibit low ESR.
See Table 2.
Input Bypass Capacitors
The input bypass capacitor (C1) reduces peak currents
drawn from the voltage source and also reduces noise
at the voltage source caused by the switching action of
the MAX770–MAX773. The input voltage source imped-
ance determines the size of the capacitor required at
the V+ input. As with the output filter capacitor, a low-
ESR capacitor is recommended. For output currents up
to 1A, 150μF (C1) is adequate, although smaller
bypass capacitors may also be acceptable.
Bypass the IC with a 0.1μF ceramic capacitor (C2)
placed close to the V+ and GND pins.
Reference Capacitor
Bypass REF with a 0.1μF capacitor (C3). REF can
source up to 100μA of current.
S etting the Low-Battery-Detec tor V oltage
To set the low-battery detector’s falling trip voltage
(V
TRIP
(falling)), select R3 between 10k
and 500k
(Figure 9), and calculate R4 as follows:
V
TRIP
- V
REF
V
REF
R4 = (R3)
(
———————
)
where V
REF
= 1.5V.
The rising trip voltage is higher because of the com-
parator’s approximately 20mV of hysteresis, and is
determined by:
R4
R3
V
TRIP
(rising) = (V
REF
+ 20mV) (1 + ——)
Connect a high value resistor (larger than R3 + R4)
between LBI and LBO if additional hysteresis is required.
Connect a pull-up resistor (e.g., 100k
) between LBO
and V+. Tie LBI to GND and leave LBO floating if the
low-battery detector is not used.
__________Applic ations Information
MAX 773 Operation with High
Input/Output V oltages
The MAX773’s shunt regulator input allows high volt-
ages to be converted to very high voltages. Since the
MAX773 runs off the 6V shunt (bootstrapped operation
is not allowed), the IC will not see the high input volt-
age. Use an external logic-level N-FET as the power
switch, since only 6V of V
GS
are available. Also, make
sure all external components are rated for very high
output voltage. Figure 3e shows a circuit that converts
28V to 100V.
Low Input V oltage Operation
When using a power supply that decays with time
(such as a battery), the N-FET transistor will operate in
its linear region when the voltage at EXT approaches
the threshold voltage of the FET, dissipating excessive
power. Prolonged operation in this mode may damage
the FET. This effect is much more significant in non-
bootstrapped mode than in bootstrapped mode, since
bootstrapped mode typically provides much higher
V
GS
voltages. To avoid this condition, make sure V
EXT
is above the V
TH
of the FET, or use a voltage detector
(such as the MAX8211) to put the IC in shutdown mode
once the input supply voltage falls below a predeter-
mined minimum value. Excessive loads with low input
voltages can also cause this condition.
5V /12V /15V or Adjustable, High-Efficiency,
Low I
Q
, Step-Up DC-DC Controllers
18
______________________________________________________________________________________
MAX773
LBI
LBO
GND
V+
R4
V
IN
R5
100k
R3
LOW-BATTERY
OUTPUT
V
V
REF
R4 = R3
(
-1
)
V
REF
= 1.5V
Figure 9. Input Voltage Monitor Circuit
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX772CSA+ | 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 |
| MAX772CSA+T | 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 |
| MAX772CSA-T | 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 |
| MAX772EPA | 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 |
| MAX772ESA | 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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