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参数资料
| 型号： | MAX867EUA+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BOOST ADJ 2.5MA 8UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 类型： | 升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 2.7 V ~ 6 V |
| 输入电压： | 0.8 V ~ 6 V |
| 频率 - 开关： | 250kHz |
| 电流 - 输出： | 2.5mA |
| 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-TSSOP，8-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 8-uMAX |
3.3V/5V or Adjustable-Output,
Single-Cell DC-DC Converters
FOR V TH > 1.25V
FOR V TH < 1.25V
V IN
OUT
6
Q1
MMDFZP02E V OUT (3.3V/5V)
MAX866
V IN
R3
MAX866
LBI
5
R5
MAX866
LBO
4
R9
1M
R11
1M
LBI
5
R4
OUT
6
R6
LBI
5
(1.25V)
R7
R10
1M
Q2
2N3904
R8
1M
)
R3 = R4
(
V TH
V REF
-1
R5 = R6
(
V REF - V TH
V OUT - V REF
)
LOAD
WHERE V TH = THE V IN TRIP THRESHOLD
WHERE V TH = THE V IN TRIP THRESHOLD
Figure 3. Low-Battery Detector Circuits
Since the input bias current at FB has a maximum value
of 100nA, large values (10k ? to 300k ? ) can be used
for R1 and R2 with no significant accuracy loss. For 1%
error, the current through R1 should be at least 100
times FB’s bias current.
Figure 4. Low-Voltage Start-Up Circuit
Figure 3. This circuit uses V OUT (3.3V or 5.0V in the
MAX866, adjustable in MAX867) as a reference. The
voltage divider formed by R5 and R6 allows the effec-
tive trip point of V IN to be set below 1.25V. R6 is usually
set to approximately 100k ? , and R5 is given by the
Low-Battery Detection, V TH > 1.25V
The MAX866 series contains an on-chip comparator for
formula:
R5 = [R6 x (V REF - V TH )] / (V OUT - V REF )
R3 = R4 ( ____ - 1 )
low-battery detection. If the voltage at LBI falls below
the regulator’s internal reference voltage (1.25V), LBO
(an open-drain output) sinks current to GND. The low-
battery monitor’s threshold is set by two resistors, R3
and R4 (Figure 3). Set the threshold voltage using the
following equation:
V TH
V REF
where V TH is the desired threshold of the low-battery
detector and V REF is the internal 1.25V reference.
Since the LBI current is less than 100nA, large resistor
values (typically 10k ? to 300k ? ) can be used for R3
and R4 to minimize loading of the input supply.
When the voltage at LBI is below the internal threshold,
LBO sinks current to GND. Connect a pull-up resistor of
100k ? or more from LBO to OUT when driving CMOS
circuits. When LBI is above the threshold, the LBO out-
put is off. If the low-battery comparator is not used,
connect LBI to V IN and leave LBO open.
Low-Battery Detection, V TH < 1.25V
When the low-battery detection threshold voltage is
below 1.25V, use the circuit shown on the right in
Note that LBI drops below the 1.25V LBI threshold trip
point when either V IN or V OUT is low.
Since V OUT regulation and the LBI threshold are derived
from the same internal voltage reference, they track
together over temperature.
Low-Battery Start-Up
The MAX866/MAX867 are bootstrapped circuits; they
can start under no-load conditions at much lower bat-
tery voltages than under full load. Once started, the out-
put can maintain a moderate load as the battery volt-
age decreases below the start-up voltage (see Typical
Operating Characteristics). The circuit shown in Figure
4 allows the circuit to start with no load, then uses the
LBI circuit and an external low-threshold P-channel
MOSFET switch to apply the load after the output has
started.
Resistors R7 and R8 are selected to trip the LBI detec-
tor at about 90% of the output voltage. On start-up, LBI
and LBO are low, Q2 is off, and transistor Q1’s gate is
held high by R11. This disconnects the load, allowing
the MAX866 to bootstrap itself at the lowest possible
voltage. When the output reaches its final output volt-
age, LBI and LBO go high, turning on Q2, Q1, and the
load.
_______________________________________________________________________________________
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| MAX867EUA+ | 功能描述:直流/直流开关转换器 3.3/5/AdjV 1-Cell 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 |
| MAX867EUA+T | 功能描述:直流/直流开关转换器 3.3/5/AdjV 1-Cell 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 |
| MAX867EUA-G063 | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX867EUA-T | 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 |
| MAX867EUA-TG063 | 制造商:Maxim Integrated Products 功能描述:- Tape and Reel |
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