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参数资料
| 型号： | MAX038CWP+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 2/17页 |
| 文件大小： | 0K |
| 描述： | IC GEN WAVEFORM HI-FREQ 20-SOIC |
| 标准包装： | 36 |
| 频率： | 0.1Hz ~ 20MHz |
| 电源电压： | 4.75 V ~ 5.25 V |
| 电流 - 电源： | 45mA |
| 工作温度： | 0°C ~ 70°C |
| 封装/外壳： | 20-SOIC（0.295"，7.50mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 20-SOIC W |
| 安装类型： | 表面贴装 |
When the MAX038’s frequency is controlled by a volt-
age source (VIN) in series with a fixed resistor (RIN), the
output frequency is a direct function of VIN as shown in
the above equations. Varying VIN modulates the oscilla-
tor frequency. For example, using a 10k
Ω resistor for
RIN and sweeping VIN from 20mV to 7.5V produces
large frequency deviations (up to 375:1). Select RIN so
that IIN stays within the 2A to 750A range. The band-
width of the IIN control amplifier, which limits the modu-
lating signal’s highest frequency, is typically 2MHz.
IIN can be used as a summing point to add or subtract
currents from several sources. This allows the output
frequency to be a function of the sum of several vari-
ables. As VIN approaches 0V, the IIN error increases
due to the offset voltage of IIN.
Output frequency will be offset 1% from its final value
for 10 seconds after power-up.
FADJ Input The output frequency can be modulated by
FADJ, which is intended principally for fine frequency
control, usually inside phase-locked loops. Once the
funda-mental, or center frequency (Fo) is set by IIN, it
may be changed further by setting FADJ to a voltage
other than 0V. This voltage can vary from -2.4V to
+2.4V, causing the output frequency to vary from 1.7 to
0.30 times the value when FADJ is 0V (Fo ±70%).
Voltages beyond ±2.4V can cause instability or cause
the frequency change to reverse slope.
The voltage on FADJ required to cause the output to
deviate from Fo by Dx (expressed in %) is given by the
formula:
VFADJ = -0.0343 x Dx
[5]
where VFADJ, the voltage on FADJ, is between -2.4V
and +2.4V.
Note: While IIN is directly proportional to the fundamen-
tal, or center frequency (Fo), VFADJ is linearly related to
% deviation from Fo. VFADJ goes to either side of 0V,
corresponding to plus and minus deviation.
The voltage on FADJ for any frequency is given by the
formula:
VFADJ = (Fo - Fx) ÷ (0.2915 x Fo) [6]
where:
Fx = output frequency
Fo = frequency when VFADJ = 0V.
Likewise, for period calculations:
VFADJ = 3.43 x (tx- to) ÷ tx
[7]
where:
tx = output period
to = period when VFADJ = 0V.
Conversely, if VFADJ is known, the frequency is given
by:
Fx = Fo x (1 - [0.2915 x VFADJ])
[8]
and the period (tx) is:
tx = to ÷ (1 - [0.2915 x VFADJ])
[9]
Programming FADJ
FADJ has a 250A constant current sink to V- that must
be furnished by the voltage source. The source is usu-
ally an op-amp output, and the temperature coefficient
of the current sink becomes unimportant. For manual
adjustment of the deviation, a variable resistor can be
used to set VFADJ, but then the 250A current sink’s
temperature coefficient becomes significant. Since
external resistors cannot match the internal tempera-
ture-coefficient curve, using external resistors to pro-
gram VFADJ is intended only for manual operation,
when the operator can correct for any errors. This
restriction does not apply when VFADJ is a true voltage
source.
A variable resistor, RF, connected between REF (+2.5V)
and FADJ provides a convenient means of manually
setting the frequency deviation. The resistance value
(RF) is:
RF = (VREF - VFADJ) ÷ 250A
[10]
VREF and VFADJ are signed numbers, so use correct
algebraic convention. For example, if VFADJ is -2.0V
(+58.3% deviation), the formula becomes:
RF = (+2.5V - (-2.0V)) ÷ 250A
= (4.5V) ÷ 250A
= 18k
Ω
Disabling FADJ
The FADJ circuit adds a small temperature coefficient
to the output frequency. For critical open-loop applica-
tions, it can be turned off by connecting FADJ to GND
(not REF) through a 12k
Ω resistor (R1 in Figure 2). The -
250A current sink at FADJ causes -3V to be devel-
oped across this resistor, producing two results. First,
the FADJ circuit remains in its linear region, but discon-
nects itself from the main oscillator, improving tempera-
ture stability. Second, the oscillator frequency doubles.
If FADJ is turned off in this manner, be sure to correct
equations 1-4 and 6-9 above, and 12 and 14 below by
doubling Fo or halving to. Although this method doubles
the normal output frequency, it does not double the
upper frequency limit. Do not operate FADJ open cir-
cuit or with voltages more negative than -3.5V. Doing
so may cause transistor saturation inside the IC, lead-
ing to unwanted changes in frequency and duty cycle.
High-Frequency Waveform Generator
MAX038
10
Maxim Integrated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX038CWP+ | 功能描述:时钟发生器及支持产品 RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| MAX038CWP+T | 功能描述:时钟发生器及支持产品 RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| MAX038CWP-T | 功能描述:时钟发生器及支持产品 RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| MAX038EPP | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:High-Frequency Waveform Generator |
| MAX038EVKIT | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:Evaluation Kit for the MAX038 |
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