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參數(shù)資料
| 型號(hào)： | MAX1843 |
| 廠(chǎng)商： | Maxim Integrated Products, Inc. |
| 英文描述： | 2.7A, 1MHz, Low-Voltage, Step-Down Regulator with Internal Synchronous Rectification in QFN Package |
| 中文描述： | 2.7A、1MHz、低電壓、降壓型穩(wěn)壓器，內(nèi)置同步整流，TQFN封裝 |
| 文件頁(yè)數(shù)： | 6/13頁(yè) |
| 文件大?。?/td> | 366K |
| 代理商： | MAX1843 |
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M
2.7A, 1MHz, Low-Voltage, Step-Down Regulator with
Internal Synchronous Rectification in QFN Package
6
_______________________________________________________________________________________
Detailed Description
The MAX1843 synchronous, current-mode, constant-off-
time, PWM DC-DC converter steps down input voltages
of +3V to +5.5V to a preset output voltage of +2.5V,
+1.8V, or +1.5V, or to an adjustable output voltage from
+1.1V to V
IN
. It delivers up to 2.7A of output current.
Internal switches composed of a 0.09
PMOS power
switch and a 0.07
NMOS synchronous-rectifier switch
improve efficiency, reduce component count, and elimi-
nate the need for an external Schottky diode.
The MAX1843 optimizes efficiency by operating in con-
stant-off-time mode under heavy loads and in Maxim
’
s
proprietary idle mode under light loads. A single resistor-
programmable constant-off-time control sets switching
frequencies up to 1MHz, allowing the user to optimize
performance trade-offs in efficiency, switching noise,
component size, and cost. Under low-dropout conditions,
the device operates in a 100% duty-cycle mode, where
the PMOS switch remains continuously on. Idle mode
enhances light-load efficiency by skipping cycles, thus
reducing transition and gate-charge losses.
When power is drawn from a regulated supply, constant-
off-time PWM architecture essentially provides constant-
frequency operation. This architecture has the inherent
advantage of quick response to line and load transients.
The MAX1843
’
s current-mode, constant-off-time PWM
architecture regulates the output voltage by changing
the PMOS switch on-time relative to the constant off-
time. Increasing the on-time increases the peak induc-
tor current and the amount of energy transferred to the
load per pulse.
Modes of Operation
The current through the PMOS switch determines the
mode of operation: constant-off-time mode (for load
currents greater than half the idle mode threshold, of
idle mode), or idle mode (for load currents less than
half the idle-mode threshold). Current sense is
achieved through a proprietary architecture that elimi-
nates current-sensing I
2
R losses.
Pin Description
NAME
FUNCTION
2, 4
IN
Supply Voltage Input
—
for the internal PMOS power switch
PIN
3, 18, 19,
23, 25
LX
Connection for the drains of the PMOS power switch and NMOS synchronous-rectifier switch. Connect
the inductor from this node to the output filter capacitor and load.
6
SS
Soft-Start. Connect a capacitor from SS to GND to limit inrush current during startup.
7
COMP
Integrator Compensation. Connect a capacitor from COMP to V
CC
for integrator compensation. See
Integrator Amplifier
section.
8
TOFF
Off-Time Select Input. Sets the PMOS power switch off-time during constant-off-time operation. Connect a
resistor from TOFF to GND to adjust the PMOS switch off-time.
9
FB
Feedback Input
—
for both preset-output and adjustable-output operating modes. Connect directly to
output for fixed-voltage operation or to a resistive divider for adjustable operating modes.
13, back-
side pad
GND
Analog Ground. Connect exposed backside pad to pin 13.
14
15
REF
FBSEL
Reference Output. Bypass REF to GND with a 1μF capacitor.
Feedback Select Input. Selects output voltage. See Table 2 for programming instructions.
16
V
CC
Analog Supply Voltage Input. Supplies internal analog circuitry. Bypass V
CC
with a 10
and 2.2μF low-
pass filter. See Figure 1.
17, 20, 21
PGND
Power Ground. Internally connected to the internal NMOS synchronous-rectifier switch.
1, 5, 10,
11, 12,
22, 24,
26, 28
N.C.
Not internally connected.
27
SHDN
Shutdown Control Input. Drive
SHDN
low to disable the reference, control circuitry, and internal
MOSFETs. Drive high or connect to V
CC
for normal operation.
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PDF描述 |
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| MAX1843EGI | 2.7A, 1MHz, Low-Voltage, Step-Down Regulator with Internal Synchronous Rectification in QFN Package |
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| MAX1845ETX | Dual, High-Efficiency, Step-Down Controller with Accurate Current Limit |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1843EGI | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MAX1843EGI+ | 制造商:Maxim Integrated Products 功能描述:2.7A, 1MHZ, INTERNAL SWITCH STEP DOWN REGULATOR - Rail/Tube |
| MAX1843EGI+T | 制造商:Maxim Integrated Products 功能描述:CONV DC-DC SGL-OUT STEP DOWN 28QFN EP - Tape and Reel |
| MAX1843EGI-T | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MAX1843ETI+ | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 2.7A 1MHz Step-Down RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
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