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参数资料
| 型号： | MAX686EEE+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 13/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BOOST INV +/-27.5V 16QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 升压（升压），反相 |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | ±27.5V |
| 输入电压： | 2.7 V ~ 5.5 V |
| 频率 - 开关： | 300kHz |
| 电流 - 输出： | 100mA |
| 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： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 16-QSOP |
DAC-Controlled Boost/Inverter
LCD Bias Supply with Internal Switch
V IN = 0.8V
TO 27.5V
22 μ H
MBR0530L
V OUT
V IN = 0.8V
TO 27.5V
22 μ H
MBR0530L
V OUT
V CC
LX
R2
R3
R6
I LCD
V CC
LX
R3
R2
R6
I LCD
DACOUT
R7
V OUTSW
DACOUT
R7
V OUTSW
LCDON
LCDON
FB
POSITIVE
OUTPUT
VOLTAGE
FB
POSITIVE
OUTPUT
VOLTAGE
R4
R5
POK
MAX686
R1
MAX686
POK
R1
GND
Figure 6. Using the POK for Input Voltage Monitoring
Feed-Forward Capacitors
Parallel a feed-forward capacitor (C F ) across R2 to com-
pensate the feedback loop and ensure stability (Figure
4). Use values up to 100pF for most applications.
Choose the lowest capacitor value that ensures stability;
high capacitance values may degrade line regulation.
Applications Information
Using a Potentiometer to Adjust the
Output Voltage
The output can be adjusted with a potentiometer
instead of the DAC (Figure 5). Choose R POT = 100k ?
and connect it between REF and GND. Connect R3 to
the potentiometer’s wiper instead of to DACOUT. Use
the same design equations for adjusting the output volt-
age with the DAC.
Controlling the LCD Using
POK and L C D O N
When the voltage at POK is greater than 1.125V (typical),
the open-drain LCDON output pulls low. LCDON can
withstand up to 27.5V to control an external PNP transis-
tor to switch on the MAX686’s positive output (Figures 6
and 7). A PFET can also be used, but a resistor-divider
must be used in conjunction with it, so that the PFET does
not exceed its V GS rating. Three useful applications of
this feature are as follows:
? An off-switch driver to ensure that a positive boosted
output goes to 0V during shutdown. Connect POK to
SHDN . Without this switch, the positive output falls to
GND
Figure 7. Using the POK for Output Voltage Monitoring
one diode drop below the input voltage (V IN ) in shut-
down. LCDON is not needed for negative outputs,
which already fall to 0V in shutdown.
? An input-sensing cutoff for positive outputs. Connect
POK to a voltage divider to sense the input voltage.
The output switches on only when the input reaches
the set level (Figure 6).
? An output-sensing cutoff for positive outputs. Connect
POK to the feedback voltage divider to sense the out-
put voltage. The output switches on only when it
reaches 90% of the set voltage (Figure 7).
For positive output voltage sensing, connect POK
directly to FB to monitor the output voltage (Figure 7).
The POK threshold is 10% less than the set voltage at
FB. Therefore, when the output voltage drops 10%
below its set value, the POK circuit turns off the external
PNP transistor, disconnecting the load.
For input voltage sensing, a resistor-divider (R4-R5,
Figure 6) from VIN to POK controls the open-drain out-
put LCDON , which pulls low when V POK > 1.125V.
Choose R5 = 100k ? . For example, if the minimum bat-
tery voltage is 5.3V, then determine R4 as follows:
R4 = R5 x [(V IN / V POK ) - 1]
= 100k x [(5.3 / 1.125) -1] = 371k ?
LCDON typically drives a low-cost PNP transistor (such
as a 2N2907 or equivalent), switching a positive VOUT to
the LCD. Choose a PNP with low V CESAT at the required
load current. R7 limits the base current in the PNP, and
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX686EVKIT | 功能描述:直流/直流开关转换器 Evaluation Kit for the MAX686 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 |
| MAX6870ETJ | 功能描述:监控电路 RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX6870ETJ+ | 功能描述:监控电路 EEPROM-Prog Hex Power-Sup Sequencer RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX6870ETJ+T | 功能描述:监控电路 EEPROM-Prog Hex Power-Sup Sequencer RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX6870ETJ-T | 功能描述:监控电路 RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
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