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| 型号： | MAX977ESD+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 5/17页 |
| 文件大小： | 0K |
| 描述： | IC COMPARATOR DUAL 14-SOIC |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 类型： | 通用 |
| 元件数： | 2 |
| 输出类型： | CMOS，满摆幅，TTL |
| 电压 - 电源，单路/双路(±)： | 2.7 V ~ 5.25 V |
| 电压 - 输入偏移（最小值）： | 2mV @ 5V |
| 电流 - 输入偏压（最小值）： | 0.1µA @ 5.25V |
| 电流 - 静态（最大值）： | 500µA |
| CMRR, PSRR（标准）： | 90dB CMRR，90dB PSRR |
| 传输延迟（最大）： | 820ns |
| 磁滞： | 4mV |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 14-SOIC（0.154"，3.90mm 宽） |
| 安装类型： | 表面贴装 |
| 包装： | 管件 |
| 产品目录页面： | 1386 (CN2011-ZH PDF) |
__________Applications Information
Powering Circuitry with STAT
STAT’s function is to indicate the comparator’s operat-
ing mode. When STAT is low, the comparator is in high-
speed mode and will meet the guaranteed propagation
delay. When STAT is high, the comparator is in auto-
standby mode, in low-power mode, or in transition to
high-speed mode. An additional feature of this pin is
that it can source 3mA of current. When STAT is high,
additional circuitry can be powered. This circuitry can
be automatically powered up or powered down,
depending on the input signal or lack of input signal
received by the MAX975/MAX977.
STO_ Considerations
The charge currents for the capacitor connected to
STO_ are on the order of 100nA. This necessitates cau-
tion in capacitor type selection and board layout.
Capacitor leakage currents must be less than 1nA to
prevent timing errors. Ceramic capacitors are available
in values up to 1F, and are an excellent choice for this
application. If a larger capacitance value is needed,
use parallel ceramic capacitors to get the required
capacitance. Aluminum and tantalum electrolytic
capacitors are not recommended due to their higher
leakage currents.
Board layout can create timing errors due to parasitic
effects. Make the STO_ traces as short as possible to
reduce capacitance and coupling effects. When driving
STO_ to disable auto-standby mode, use standard
CMOS logic isolated with a low-leakage (<1nA) diode,
such as National’s FJT1100 (Figure 3). 15nA leakage
typically results in 10% error.
The MAX977 has separate timing inputs (STOA and
STOB). These pins must have separate capacitors. The
timing circuits will not operate correctly if a single
capacitor is used with STOA and STOB connected
together.
The relationship between the timeout period and the
STO_ capacitor is tASB = 10 x CSTO_
s, where CSTO_
is in pF. This equation is for larger capacitance values,
and does not take into account variations due to board
capacitance and board leakage. If less than 1ms is
desired, subtract the ~3pF STO_ parasitic capacitance
from the calculated value.
Circuit Layout and Bypassing
The MAX975/MAX977’s high gain bandwidth requires
design precautions to realize the comparator’s full high-
speed capability. The following precautions are recom-
mended:
1) Use a printed circuit board with an unbroken, low-
inductance ground plane.
2) Place a decoupling capacitor (a 0.1F ceramic
capacitor is a good choice) as close to VCC as pos-
sible.
3) Keep lead lengths short on the inputs and outputs, to
avoid unwanted parasitic feedback around the com-
parators.
4) Solder the devices directly to the printed circuit
board instead of using a socket.
5) Minimize input impedance.
6) For slowly varying inputs, use a small capacitor
(~1000pF) across the inputs to improve stability.
IR Receiver
Figure 4 shows an application using the MAX975 as an
infrared receiver. The infrared photodiode creates a
current relative to the amount of infrared light present.
This current creates a voltage across RD. When this
voltage level crosses the voltage applied by the voltage
divider to the inverting input, the output transitions. If
the photodiode is not receiving enough signal to cause
transitions on the MAX975’s output, STAT is used as a
loss-of-signal indicator. R3 adds additional hysteresis
for noise immunity.
MAX975/MAX977
Single/Dual, +3V/+5V Dual-Speed
Comparators with Auto-Standby
______________________________________________________________________________________
13
STO_
CMOS
LOGIC
Figure 3. Driving STO
_ with CMOS Logic
GND
STAT
VCC
RD
R1
R2
R3
OUT
LOSS OF SIGNAL
MAX975
VCC
Figure 4. IR Receiver
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX977ESD+ | 功能描述:校验器 IC 3V/5V Dual-Speed Comparator RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
| MAX977ESD+T | 功能描述:校验器 IC 3V/5V Dual-Speed Comparator RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
| MAX977ESD-T | 功能描述:校验器 IC RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
| MAX9787ETI+ | 功能描述:音频放大器 Integrated Circuits (ICs) RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| MAX9787ETI+T | 功能描述:音频放大器 Integrated Circuits (ICs) RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
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