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參數(shù)資料
| 型號： | MAX984 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | µ.P Reset IC with Battery-Backup[MAX703/MAX704/MAX703/MAX704/MAX703/MAX704/MAX703C/D/MAX703CPA/MAX703CSA/MAX703CSA-T/MAX703EPA/MAX703ESA/MAX703ESA-T/MAX703MJA/MAX704C/D/MAX704CPA/MAX704CSA/MAX704CSA-T/MAX704EPA/MAX704ESA/MAX704ESA-T/MAX704MJA] |
| 中文描述： | 超低功耗、漏極開路輸出、單/雙電源比較器 |
| 文件頁數(shù)： | 11/17頁 |
| 文件大?。?/td> | 325K |
| 代理商： | MAX984 |
M
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
______________________________________________________________________________________
11
__________Applications Information
Hysteresis
Hysteresis increases the comparators
’
noise margin by
increasing the upper threshold and decreasing the
lower threshold (Figure 2).
Hysteresis (MAX9_1/MAX982/MAX9_3)
To add hysteresis to the MAX9_1, MAX982, or MAX9_3,
connect resistor R1 between REF and HYST, and
connect resistor R2 between HYST and V- (Figure 3). If
no hysteresis is required, connect HYST to REF. When
hysteresis is added, the upper threshold increases by
the same amount that the lower threshold decreases.
The hysteresis band (the difference between the upper
and lower thresholds, V
HB
) is approximately equal to
twice the voltage between REF and HYST. The HYST
input can be adjusted to a maximum voltage of REF
and to a minimum voltage of (REF - 50mV). The
maximum difference between REF and HYST (50mV)
will therefore produce a 100mV (max) hysteresis band.
Use the following equations to determine R1 and R2:
V
2
×
(
where I
REF
(the current sourced by the reference)
should not exceed the REF source capability, and
should be significantly larger than the HYST input
current. I
REF
values between 0.1μA and 4μA are usually
appropriate. If 2.4M
is chosen for R2 (I
REF
= 0.5μA),
the equation for R1 and V
HB
can be approximated as:
R1 (k ) = V
When hysteresis is obtained in this manner for the
MAX982/MAX9_3, the same hysteresis applies to both
comparators.
Hysteresis (MAX972/MAX9_4)
Hysteresis can be implemented with any comparator
using positive feedback, as shown in Figure 4. This
approach generally draws more current than circuits
using the HYST pin on the MAX9_1/MAX982/MAX9_3,
and the high feedback impedance slows hysteresis. In
addition, because the output does not source current,
any increase in the upper threshold is dependent on
the load or pullup resistor on the output.
Board Layout and Bypassing
Power-supply bypass capacitors are not needed if the
supply impedance is low, but 100nF bypass capacitors
should be used when the supply impedance is high or
when the supply leads are long. Minimize signal lead
lengths to reduce stray capacitance between the input
and output that might cause instability. Do not bypass
the reference output.
Window Detector
The MAX9_3 is ideal for making window detectors
(undervoltage/overvoltage detectors). The schematic is
shown in Figure 5, with component values selected for a
4.5V undervoltage threshold and a 5.5V overvoltage
threshold. Choose different thresholds by changing the
values of R1, R2, and R3. To prevent chatter at the
hysteresis has been added using R4 and R5. Taken
alone, OUTA would provide an active-low undervoltage
indication, and OUTB would give an active-low
overvoltage indication. Wired-ORing the two outputs
provides an active-high, power-good signal.
The design procedure is as follows:
1) Choose the required hysteresis level and calculate
values for R4 and R5 according to the formulas in
the
Hysteresis (MAX9_1/MAX982/MAX9_3)
section.
In this example, ±5mV of hysteresis has been added
at the comparator input (V
H
= V
HB
/2). This means
that the hysteresis apparent at V
IN
will be larger
because of the input resistor divider.
(mV)
HB
R1 =
I
R2 =
1.182
–
V
2
I
HB
REF
HB
REF
)
GND
V-
V+
MAX9_4
OUT
R
H
R
PULLUP
V
REF
V
IN
V+
Figure 4. External Hysteresis
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| MAX98400AETX+ | 功能描述:音頻放大器 Stereo Class D Amplifier RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX98400AETX+T | 功能描述:音頻放大器 Stereo Class D Amplifier RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX98400AEVKIT+ | 功能描述:音頻 IC 開發(fā)工具 MAX98400A Eval Kit RoHS:否 制造商:Texas Instruments 產(chǎn)品:Evaluation Kits 類型:Audio Amplifiers 工具用于評估:TAS5614L 工作電源電壓:12 V to 38 V |
| MAX98400BETG+ | 功能描述:音頻放大器 Stereo Class D Amplifier RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX98400BETG+T | 功能描述:音頻放大器 Stereo Class D Amplifier RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
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