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参数资料
| 型号： | MAX1703 |
| 厂商： | Maxim Integrated Products, Inc. |
| 元件分类： | DC/DC变换器 |
| 英文描述： | 1-Cell to 3-Cell, High-Power 1.5A, Low-Noise, Step-Up DC-DC Converter |
| 中文描述： | 1节至3节电池、大功率(1.5A)、低噪声、升压型DC-DC转换器 |
| 文件页数： | 10/16页 |
| 文件大小： | 273K |
| 代理商： | MAX1703 |
M
Synchronized PWM Operation
The MAX1703 can be synchronized in PWM mode to a
200kHz to 400kHz frequency by applying an external
clock to CLK/SEL. This allows the user to set the har-
monics to avoid IF bands in wireless applications. The
synchronous rectifier is also active during synchronized
PWM operation.
Low-Power PFM Operation
Pulling CLK/SEL low places the MAX1703 in a low-
power mode. During low-power mode, PFM operation
regulates the output voltage by transferring a fixed
amount of energy during each cycle, and then modulat-
ing the pulse frequency to control the power delivered
to the output. The devices switch only as needed to
service the load, resulting in the highest possible effi-
ciency at light loads. Output current capability in PFM
mode is 150mA (max). The output voltage is typically
1% higher than in PWM mode.
During PFM operation, the error comparator detects the
output voltage falling out of regulation and sets a flip-
flop, which turns on the N-channel MOSFET switch
(Figure 4). When the inductor current ramps to the PFM
mode current limit (800mA typical) and stores a fixed
amount of energy, the current-sense comparator resets
a flip-flop. The flip-flop turns off the N-channel switch
and turns on the P-channel synchronous rectifier. A
second flip-flop, previously reset by the switch’s “on” sig-
nal, inhibits the error comparator from initiating another
cycle until the energy stored in the inductor is transferred
to the output filter capacitor and the synchronous rectifier
current has ramped down to 80mA. This forces operation
with a discontinuous inductor current.
Synchronous Rectifier
The MAX1703 features an internal 140m
, P-channel
synchronous rectifier to enhance efficiency. Synchro-
nous rectification provides a 5% efficiency improve-
ment over similar nonsynchronous boost regulators. In
PWM mode, the synchronous rectifier is turned on dur-
ing the second half of each switching cycle. In low-
power mode, an internal comparator turns on the
synchronous rectifier when the voltage at LX exceeds
the boost regulator output, and then turns it off when
the inductor current drops below 80mA.
Low-Voltage Start-Up Oscillator
The MAX1703 uses a CMOS, low-voltage start-up oscil-
lator for a 1.1V guaranteed minimum start-up input volt-
age at +25°C. On start-up, the low-voltage oscillator
switches the N-channel MOSFET until the output volt-
age reaches 2.15V. Above this level, the normal boost-
converter feedback and control circuitry take over.
Once the device is in regulation, it can operate down to
a 0.7V input, since internal power for the IC is boot-
strapped from the output via the OUT pin. Do not apply
full load until the output exceeds 2.3V (max).
1-Cell to 3-Cell, High-Power (1.5A),
Low-Noise, Step-Up DC-DC Converter
10
______________________________________________________________________________________
2.7A TYP
CURRENT
LIMIT
OSC
FB
R
Q
S
REF
LXP
LXN
POUT
PGND
P
N
Figure 3. Simplified PWM Controller Block Diagram
ERROR
COMPARATOR
FB
REF
800mA TYP
CURRENT
LIMIT
LOGIC HIGH
POUT
P
N
PGND
S
S
Q
R
D
Q
R
LXP
LXN
Figure 4. Controller Block Diagram in Low-Power PFM Mode
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相关代理商/技术参数 |
参数描述 |
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| MAX17030EVKIT+ | 功能描述:电源管理IC开发工具 MAX17030 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX17030GTL+ | 功能描述:电压模式 PWM 控制器 1/2/3-Phase PWM IMVP-6.5 VID Ctlr RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17030GTL+T | 功能描述:电压模式 PWM 控制器 1/2/3-Phase PWM IMVP-6.5 VID Ctlr RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17031ETG+ | 功能描述:电压模式 PWM 控制器 Dual PWM Step-Down Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17031ETG+T | 功能描述:电压模式 PWM 控制器 Dual PWM Step-Down Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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