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| 型号： | MAX761ESA+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 8/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BOOST 12V/ADJ 0.15A 8SOIC |
| 标准包装： | 100 |
| 类型： | 升压（升压） |
| 输出类型： | 两者兼有 |
| 输出数： | 1 |
| 输出电压： | 12V，5 V ~ 16.5 V |
| 输入电压： | 2 V ~ 16.5 V |
| 频率 - 开关： | 300kHz |
| 电流 - 输出： | 150mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 8-SOIC |
12V/15V or Adjustable, High-Efficiency,
Low I Q , Step-Up DC-DC Converters
V IN =
+5V
L1
18μH
D1
1N5817
+12V at
150mA
V IN
L1
18μH
D1
1N5817
ADJUSTABLE
OUTPUT (V OUT )
C1
33μF
C4
33μF
C4
R2 = R1
REF
( V OUT -1 )
7
7
R4
C3
0.1μF
5
4
REF
SHDN
LX
MAX761
V+
8
C2
R4
C1
C2
8
2
V+
LBI
LX
MAX761
MAX762
FB
3
R2
100k
2
LBI
0.1μF
100k
5
REF
R1
R3
C3
R3
3
FB
LBO
1
4
SHDN
LBO
1
(
VTRIP - VREF
GND
6
LOW-BATTERY
OUTPUT
LOW-BATTERY
DETECT
R4 = R3
VREF
)
GND
6
LOW-BATTERY
DETECT OUTPUT
V REF = 1.5V NOMINAL
Figure 2. Bootstrapped Operating Circuit
In non-bootstrapped mode, the IC is powered from the
supply voltage, V IN , and operates with minimum supply
current. Since the voltage applied to the gate of the inter-
nal FET is reduced, efficiency declines with low input
voltages. Note: In non-bootstrapped mode, there is no
fixed-output operation; external resistors must be
used to set the output voltage. Use 1% external feed-
back resistors when operating in non-bootstrapped
mode (Figure 3).
Use bootstrapped mode when V IN is below approxi-
mately 4V. For V IN between 4V and 6V, the trade-off is
lower supply current in non-bootstrapped mode versus
higher output current in bootstrapped mode (see
Typical Operating Characteristics).
Pulse-Frequency Modulation
(PFM) Control Scheme
The MAX761/MAX762 use a proprietary current-limited
PFM control scheme. This control scheme combines
the ultra-low supply current of pulse-skipping PFM con-
verters with the high full-load efficiency characteristic of
current-mode pulse-width-modulation (PWM) convert-
ers. It allows the devices to achieve high efficiency over
a wide range of loads, while the current-sense function
and high operating frequency allow the use of tiny
external components.
As with traditional PFM converters, the internal power
MOSFET is turned on when the voltage comparator
senses the output is out of regulation (Figure 1).
However, unlike traditional PFM converters, switching is
accomplished through the combination of a peak cur-
C1 = 33μF
C2 = 0.1μF
C3 = 0.1μF
C4 = 33μF
Figure 3. Non-Bootstrapped Operating Circuit
rent limit and a pair of one-shots that set the maximum
on-time (8μs) and minimum off-time (1.3μs) for the
switch. Once off, the minimum off-time one-shot holds
the switch off for 1.3μs. After this minimum time, the
switch either (1) stays off if the output is in regulation, or
(2) turns on again if the output is out of regulation.
The MAX761/MAX762 also limit the peak inductor cur-
rent, allowing the devices to run in continuous-conduc-
tion mode (CCM) and maintain high efficiency with
heavy loads (Figure 4a). This current-limiting feature is
a key component of the control circuitry. Once turned
on, the switch stays on until either (1) the maximum on-
time one-shot turns it off (8μs later), or (2) the current
limit is reached.
To increase light-load efficiency, the current limit for the
first two pulses is set to half the peak current limit. If
those pulses bring the output voltage into regulation,
the voltage comparator holds the MOSFET off, and the
current limit remains at half the peak current limit. If the
output voltage is still out of regulation after two pulses,
the current limit for the next pulse is raised to the full
current limit of 1A (Figure 4b).
Internal vs. External Resistors
When external feedback resistors are used, an internal
undervoltage lockout system prevents start-up until V+
rises to about 2.7V. When external feedback resistors are
8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX761ESA/G0F | 制造商:Maxim Integrated Products 功能描述:12V OR ADJUSTABLE, HIGH EFFICIENCY, LOW IQ, S - Bulk |
| MAX761ESA/G0F-T | 制造商:Maxim Integrated Products 功能描述:12V OR ADJUSTABLE, HIGH EFFICIENCY, LOW IQ, S - Tape and Reel |
| MAX761ESA/GG8 | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX761ESA+ | 功能描述:直流/直流开关转换器 12/15/AdjV Step-Up DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX761ESA+T | 功能描述:直流/直流开关转换器 Integrated Circuits (ICs) RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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