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參數(shù)資料
| 型號(hào)： | MAX1734EUK__-T |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類(lèi)： | DC/DC變換器 |
| 英文描述： | Low-Voltage, Step-Down DC-DC Converters in SOT23 |
| 中文描述： | 低電壓，降壓型DC - DC轉(zhuǎn)換器采用SOT23 |
| 文件頁(yè)數(shù)： | 6/8頁(yè) |
| 文件大小： | 265K |
| 代理商： | MAX1734EUK__-T |
M
Detailed Description
The MAX1733/MAX1734 step-down DC-DC converters
deliver over 250mA to outputs as low as 1.25V. They
use a unique proprietary current-limited control scheme
that maintains extremely low quiescent supply current
(40μA), and their high 1.2MHz (max) operating frequen-
cy permits small, low-cost external components. Figure
2 is a simplified functional diagram.
Control Scheme
The MAX1733/MAX1734 use a proprietary, current-lim-
ited control scheme to ensure high-efficiency, fast tran-
sient response, and physically small external
components. This control scheme is simple: when the
output voltage is out of regulation, the error comparator
begins a switching cycle by turning on the high-side
switch. This switch remains on until the minimum on-
time of 400ns expires and the output voltage regulates
or the current-limit threshold is exceeded. Once off, the
high-side switch remains off until the minimum off-time
of 400ns expires and the output voltage falls out of reg-
ulation. During this period, the low-side synchronous
rectifier turns on and remains on until either the high-
side switch turns on again or the inductor current
approaches zero. The internal synchronous rectifier
eliminates the need for an external Schottky diode.
This control scheme allows the MAX1733/MAX1734 to
provide excellent performance throughout the entire
load-current range. When delivering light loads, the
high-side switch turns off after the minimum on-time to
reduce peak inductor current, resulting in increased
efficiency and reduced output voltage ripple. When
delivering medium and higher output currents, the
MAX1733/MAX1734 extend either the on-time or the off-
time, as necessary to maintain regulation, resulting in
nearly constant frequency operation with high efficien-
cy and low output voltage ripple.
Shutdown Mode
Connecting
SHDN
to GND places the MAX1733/
MAX1734 in shutdown mode and reduces supply cur-
rent to 0.01μA. In shutdown, the control circuitry, inter-
nal switching MOSFET, and synchronous rectifier turn
off and LX goes high impedance. Connect
SHDN
to IN
for normal operation.
Soft-Start
The MAX1733/MAX1734 have internal soft-start circuitry
that limits current draw at startup, reducing transients on
the input source. Soft-start is particularly useful for higher
impedance input sources, such as Li+ and alkaline cells.
Soft-start is implemented by starting with the current limit
at 25% of its full current value and gradually increasing it
in 25% steps until the full current limit is reached. See
Soft-Start and Shutdown Response in the
Typical
Operating Characteristics
section.
Design Information
Setting the Output Voltage (MAX1733)
Select an output voltage for the MAX1733 by connect-
ing FB to a resistive divider between the output and
Low-Voltage, Step-Down DC-DC Converters
in SOT23
6
_______________________________________________________________________________________
Figure 1. MAX1733 Typical Application Circuit
FB
R1
R2
V
OUT
C1
2.2
μ
F
C2
22
μ
F
L1
10
μ
H
LX
IN
MAX1733
SHDN
GND
INPUT
+2.7V TO +5.5V
SHDN
CONTROL
LOGIC
P
N
V
REF
OUT (FB)
LX
IN
GND
( ) ARE FOR MAX1733 ONLY.
CURRENT
LIMIT
SHUTDOWN
CONTROL
DIGITAL
SOFT-START
MAX1733
MAX1734
Figure 2. Simplified Functional Diagram
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1733 | Replaced by TMS320VC5506 : |
| MAX1733EUK | Replaced by TMS320VC5506 : Digital Signal Processors 100-LQFP 0 to 0 |
| MAX1749EUK-T | CONN, 50-PIN, ZIF, 0.5MM, PITCH SMD |
| MAX1749 | SOT23 Vibrator Motor Driver |
| MAX1757 | Stand-Alone, Switch-Mode Li Battery Charger with Internal 14V Switch |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1734EVKIT | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1735EUK25 | 制造商:Maxim Integrated Products 功能描述:LOW-DROPOUT LINEAR REGULATOR IN SOT 23 - Cut Tape Product |
| MAX1735EUK25+ | 制造商:Maxim Integrated Products 功能描述:REG LDO LIN ADJ/FIX NEG -1.25V TO -5.5V/-2.5V -0.2A 5PIN SOT - Rail/Tube |
| MAX1735EUK25+T | 功能描述:低壓差穩(wěn)壓器 - LDO 200mA Negative Output RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類(lèi)型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| MAX1735EUK25-T | 功能描述:低壓差穩(wěn)壓器 - LDO 200mA Negative Output RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類(lèi)型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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