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参数资料
| 型号： | MAX1705 |
| 厂商： | Maxim Integrated Products, Inc. |
| 元件分类： | DC/DC变换器 |
| 英文描述： | 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator |
| 中文描述： | 1至3节电池、大电流、低噪声、升压型DC-DC转换器，带有线性稳压器 |
| 文件页数： | 11/20页 |
| 文件大小： | 215K |
| 代理商： | MAX1705 |
M
1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator
______________________________________________________________________________________
11
S tep-Up Converter
The step-up switching DC-DC converter generates an
adjustable output to supply both power circuitry (such
as RF power amplifiers) and the internal low-dropout
linear regulator. During the first part of each cycle, the
internal N-channel MOSFET switch is turned on. This
allows current to ramp up in the inductor and store
energy in a magnetic field. During the second part of
each cycle, when the MOSFET is turned off, the voltage
across the inductor reverses and forces current
through the diode and synchronous rectifier to the out-
put filter capacitor and load. As the energy stored in
the inductor is depleted, the current ramps down, and
the output diode and synchronous rectifier turn off.
Voltage across the load is regulated using either PWM
or PFM operation, depending on the CLK/SEL pin set-
ting (Table 1).
Low-Noise, High-Power PWM Operation
When CLK/SEL is pulled high, the MAX1705/MAX1706
operate in a high-power, low-noise PWM mode. During
PWM operation, they switch at a constant frequency
(300kHz), and modulate the MOSFET switch pulse
width to control the power transferred per cycle and
regulate the voltage across the load. In PWM mode, the
devices can output up to 850mA. Switching harmonics
generated by fixed-frequency operation are consistent
and easily filtered.
During PWM operation, each of the internal clock’s ris-
ing edges sets a flip-flop, which turns on the N-channel
MOSFET switch (Figure 3). The switch is turned off
when the sum of the voltage-error and current-
feedback signals trips a multi-input comparator and
resets the flip-flop; the switch remains off for the rest of
the cycle. When a change occurs in the output voltage
error signal into the comparator, it shifts the level that
the inductor current is allowed to ramp to during each
cycle and modulates the MOSFET switch pulse width.
A second comparator enforces a 1.55A (max) inductor-
LX
POUT
OUT
BOOST OUTPUT 3.6V
FB
LDOOUTPUT 3.3V
INPUT 0.9V TO3.6V
(TOPGND)
(TOPGND)
PGND
GND
LDO
FBLDO
LBO
LBN
REF
MAX1705
MAX1706
LBP
CLK/SEL
ONA
ONB
TRACK
R3
165k
R4
100k
R5
R6
R7
100k
C2*
D1
C7
22
μ
F
C8
0.33
μ
F
L1 10
μ
H (22
μ
H)
*OPTIONAL.
( ) ARE FOR MAX1706.
C4
220
μ
F
(100
μ
F)
C5*
0.33
μ
F
C6
22
μ
F
R1
191k
C3
0.1
μ
F
C9
0.33
μ
F
C1*
R2
100k
NOTE: HEAVY LINES INDICATE HIGH-CURRENT PATH.
Figure 2. Typical Operating Circuit (PWM Mode)
CLK/SEL
MODE
FEATURES
0
PFM
Low supply current
1
PWM
Low noise,
high output current
External Clock
(200kHz to 400kHz)
Synchronized
PWM
Low noise,
high output current
Table 1. Selecting the Operating Mode
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17050EVKIT# | 功能描述:电源管理IC开发工具 MAX17050 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 |
| MAX17050X+ | 制造商:Maxim Integrated Products 功能描述:MODELGAUGE M3 FG WLCSP - Tape and Reel |
| MAX17050X+T10 | 制造商:Maxim Integrated Products 功能描述:MODELGAUGE M3 FG WLCSP - Tape and Reel |
| MAX17058EVKIT# | 功能描述:电源管理IC开发工具 MAX17058 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 |
| MAX17058G+ | 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:MODELGAUGE (1 CELL) TDFN - Rail/Tube |
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