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參數(shù)資料
| 型號(hào)： | AIC1653 |
| 廠商： | Analog Integrations Corporation |
| 英文描述： | Micropower Inverting DC/DC Converter in SOT-23-5 |
| 中文描述： | 微反向直流/直流轉(zhuǎn)換器采用SOT - 23 - 5 |
| 文件頁(yè)數(shù)： | 7/11頁(yè) |
| 文件大?。?/td> | 225K |
| 代理商： | AIC1653 |
AIC1653
APPLICATION INFORMATIONS
Principle of Operation
Component Selection
AIC1653 uses a constant off-time control scheme,
which is represented in Fig. 8, to provide high
efficiency over a range of output current. Q1 and
Q2 along with R3 and R4 form a bandgap
reference used to regulate the output voltage.
When the voltage at NFB pin is slightly below
-1.23V, comparator A1 disables most of the
internal circuitry. Output current is then provided by
output capacitor, which slowly discharges until the
voltage at the NFB pin goes above the hysteresis
point of A1. A1 then enables the internal circuitry to
turn power switch NMOS on, and the current in
inductor begins ramping up. Once the switch
current reaches 100mA, comparator A2 resets
one-shot, which turns NMOS off for 400ns. In the
meantime, the inductor continues to deliver current
to the output. When NMOS turns back on, the
inductor current ramps up. And A2 resets one-shot
again when switch current gets to 100mA. This
switching action continues until the output voltage
is charged up with NFB pin reaching -1.23V. Then
A1 turns the internal circuitry off and the cycle
repeats. The AIC1653 contains additional circuitry
to provide current-limit protection for start-up as
well as short-circuit protection. When FB pin
voltage is higher than –0.6V, switch off-time is
increased to 800nS. This reduces the average
inductor current and helps minimize the power
dissipation in AIC1653 power switch, and in the
external inductor and diode.
Inductor Selection – Inverting Regulator
The following formula calculates the appropriate
inductor value for an inverting regulator. This value
provides a good tradeoff in inductor size and
system performance. In any applications, the
closest value to the one from the formula needs to
be applied to the inductors (both inductors should
have the same value). A use of an inductor value
up to 22μH can induce a slight increase of output
current, but any value beyond that will result in high
output ripple voltage with no further output current
increase. The size of inductor can be reduced by
using a value under 22μH. The formula is shown
as below:
OFF
t
LIM
I
D
V
OUT
V
2
L
×
+
=
(1)
where V
D
=0.4V (Schottky diode forward voltage),
I
LIM
=100mA, and t
OFF
=400nS.
Be aware that, based on formula (1), high output
voltage can raise inductance, which may cause an
increase of inductor size.
For a converter (typical application circuit)
converting from 3.6V to –6V, a 51.2μH inductor is
calculated from the above equation. However, a
22μH inductor is recommended instead to prevent
the loss of output current.
7
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AIC1653CVBG | 制造商:AIC 制造商全稱:Analog Intergrations Corporation 功能描述:Micropower Inverting DC/DC Converter in SOT-23-5 |
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| AIC1660 | 制造商:AIC 制造商全稱:Analog Intergrations Corporation 功能描述:Switched-Capacitor Voltage Converter |
| AIC1660CN | 制造商:AIC 制造商全稱:Analog Intergrations Corporation 功能描述:Switched-Capacitor Voltage Converter |
| AIC1660CS | 制造商:AIC 制造商全稱:Analog Intergrations Corporation 功能描述:Switched-Capacitor Voltage Converter |
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