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參數(shù)資料
| 型號(hào)： | MAX1896EUT-T |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Fixed-Point Digital Signal Processor 532-FCBGA |
| 中文描述： | 0.6 A SWITCHING REGULATOR, 1800 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | MO-178AB, SOT-23, 6 PIN |
| 文件頁(yè)數(shù)： | 6/10頁(yè) |
| 文件大?。?/td> | 755K |
| 代理商： | MAX1896EUT-T |
M
1.4MHz SOT23 Current-Mode
Step-Up DC-DC Converter
6
_______________________________________________________________________________________
Detailed Description
The MAX1896 is a highly efficient power supply that
employs a current-mode, fixed-frequency pulse-width
modulation (PWM) architecture for fast-transient response
and low-noise operation. The functional diagram is shown
in Figure 2. As the load varies, the error amplifier sets the
inductor peak current necessary to supply the load and
regulate the output voltage. To maintain stability at high
duty cycle, a slope-compensation signal is internally
summed with the current-sense signal.
At light loads, this architecture allows the MAX1896 to
skip cycles to prevent overcharging the output voltage.
In this region of operation, the inductor ramps up to a
peak value of about 100mA, discharges to the output
and waits until another pulse is needed again.
Output-Current Capability
The output-current capability of the MAX1896 is a func-
tion of current limit, input voltage, and inductor value.
Because of the slope compensation used to stabilize
the feedback loop, the duty cycle affects the current
limit. The output-current capability is governed by the
following equation:
where:
I
LIM
= current limit specified at 50% (see
Electrical
Characteristics
)
V
DIODE
= catch diode forward drop at I
LIM
, (V)
f
OSC
= oscillator frequency, (Hz)
L = inductor value, (H)
η
= conversion efficiency, 0.85 nominal
V
IN
= input voltage, (V)
V
OUT
= output voltage, (V)
Soft-Start
The MAX1896 can be programmed for soft-start upon
power-up with an external capacitor. When the
MAX1896 is turned on, the soft-start capacitor (C
SS
) is
charged at a constant current of 4μA, ramping up to
0.5V. During this time, the SS voltage directly controls
the peak-inductor current, allowing 0A at V
SS
= 0.5V to
the full current limit at V
SS
= 1.5V. The maximum load
current is available after the soft-start cycle is complet-
ed. When the MAX1896 is turned off, the soft-start
capacitor is internally discharged to ground.
Shutdown
The MAX1896 shuts down to reduce the supply current
to 0.01μA when
SHDN
is low. In this mode, the internal
reference, error amplifier, comparators, biasing circuit,
and N-channel MOSFET are turned off. The step-up
converter’s output is still connected to IN via the exter-
nal inductor and output rectifier.
Applications Information
The MAX1896 operates well with a variety of external
components. The components in Figure 1 are suitable
for most applications. See the following sections to opti-
mize external components for a particular application.
Inductor Selection
Inductor selection depends on input voltage, output volt-
age, maximum current, size, and availability of inductor
values. Other factors can include efficiency and ripple
voltage. Inductors are specified by their inductance (L),
peak current (I
PK
), and resistance (R
L
). The following
step-up circuit equations are useful in choosing the
inductor values based on the application. They allow the
trading of peak current and inductor value while consid-
ering component availability and cost.
The equation used here assumes a constant LIR, which
is the ratio of the inductor peak-to-peak AC current to
average DC inductor current. A good compromise
between the size of the inductor versus loss and output
ripple is to choose an LIR of 0.3 to 0.5. The peak induc-
tor current is then given by:
where:
I
OUT(MAX)
= maximum output current, (A)
V
IN(MIN)
= minimum input voltage, (V)
I
I
x V
x V
x
LIR
2
PK
OUT MAX
(
η
OUT
IN MIN
(
+
1
)
)
=
DUTY
DUTY CYCLE
V
x R
LIM
V
V
V
I
V
OUT
IN
DIODE
+
OUT
ON
DIODE
+
=
=
I
I
Duty x V
f
x
x
V
V
OUT MAX
(
LIMx
0. x Duty
IN
OSC x L
IN
OUT
)
( .
1 45
))
(
.
η
=
×
0 5
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1896EUTTG16 | 制造商:Maxim Integrated Products 功能描述:1.4MHz Current-Mode, DC-DC Converter |
| MAX1896EVKIT | 制造商:Maxim Integrated Products 功能描述:1.4MHZ SOT23 CURRENT-MODE STEP-UP DC-DC CONVE - Bulk |
| MAX1897EGP | 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MAX1897EGP-T | 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MAX1897EGP-TG074 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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