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参数资料
| 型号： | LTC6908CDCB-2#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 16/16页 |
| 文件大小： | 0K |
| 描述： | IC OSC SILICON 10MHZ 6-DFN |
| 标准包装： | 2,500 |
| 类型： | 振荡器 - 硅 |
| 频率： | 50kHz ~ 10MHz |
| 电源电压： | 2.7 V ~ 5.5 V |
| 电流 - 电源： | 1.25mA |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 6-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 6-DFN-EP（2x3） |
| 安装类型： | 表面贴装 |
LTC6908-1/LTC6908-2
9
690812fa
APPLICATIO S I FOR ATIO
WU
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SELECTING THE FREQUENCY-SETTING RESISTOR
The LTC6908 has an output frequency range spanning
50kHz to 10MHz. However, accuracy may suffer if the
oscillator is operated at a frequency greater than 5MHz with
a supply voltage lower than 4V. With a linear relationship
correspondence between oscillation period and resistance,
a simple equation relates resistance with frequency.
RSET =10k 10MHz/fOUT
RSETMIN = 10k (5V supply), 20k (3V supply),
RSETMAX = 2M
Any resistor, RSET, tolerance will shift the output frequency,
fOUT.
ALTERNATIVE METHODS OF SETTING THE OUTPUT
FREQUENCY OF THE LTC6908
The oscillator may be programmed by any method that
sources a current into the SET pin. The circuit in Figure 5
sets the oscillator frequency using a programmable current
source and in the expression for fOUT, the resistor RSET is
replaced by the ratio of 1.1V/ICONTROL.Asalreadyexplained
in the Operation section, the voltage difference between
V+ and SET is approximately 1.1V ±5%, therefore, the
Figure 5 circuit is less accurate than if a resistor controls
the output frequency.
Figure 5. Current Controlled Oscillator
Figure 6 shows the LTC6908 congured as a VCO. A voltage
source is connected in series with an external 10k resis-
tor. The output frequency, fOUT, will vary with VCONTROL,
that is the voltage source connected between V+ and the
SET pin. Again, this circuit decouples the relationship
between the input current and the voltage between V+
Figure 6. Voltage Controlled Oscillator
and SET; the frequency accuracy will be degraded. The
oscillator frequency, however, will increase monotonically
with decreasing VCONTROL.
SETTING THE MODULATION RATE OF THE LTC6908
The modulation rate of the LTC6908 is equal to fOUT/N,
where N is the modulation rate divider setting, which is
determined by the state of the MOD pin. The MOD pin should
be tied to ground for the N = 16 setting. Floating the MOD
pin selects N = 32. The MOD pin should be tied to V+ for
the N = 64 setting. To disable the SSFM, connect one of
the outputs to the MOD pin. An AC detector circuit shuts
down the modulation circuitry if a frequency that is close
to the output frequency is detected at the MOD pin.
DRIVING LOGIC CIRCUITS
The outputs of the LTC6908 are suitable for driving gen-
eral digital logic circuits. However, the form of frequency
spreading used in the LTC6908 may not be suitable for
many logic designs. Many logic designs have fairly tight
timing and cycle-to-cycle jitter requirements. These sys-
tems often benet from a spread spectrum clocking system
where the frequency is slowly and linearly modulated by a
triangular waveform, not a pseudorandom waveform. This
type of frequency spreading maintains a minimal difference
in the timing from one clock edge to the next adjacent
clock edge (cycle-to-cycle jitter). The LTC6908 uses a
pseudorandom modulating signal where the frequency
transitions have been slowed and the corners rounded
by a rst order lowpass lter with a corner frequency set
to the modulation rate (fOUT/N), where N is the modula-
tion rate divider setting, which is determined by the state
CBYP
ICONTROL
OUT1
OUT2
OUT1
fOUT = 10k (10MHz/1.13V) ICONTROL(A)
OUT2
MOD
V+
FLOAT
GND
SET
690812 F05
CBYP
VCONTROL
OUT1
OUT2
OUT1
fOUT = 10k 10MHz/RSET(1 – VCONTROL/1.13V)
OUT2
MOD
V+
FLOAT
GND
SET
690812 F06
RSET
+
–
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC6908CS6-1 | 制造商:Linear Technology 功能描述:RESISTOR SET SOT-23 OSCILLATOR WITH SPREAD SPECTRUM MODULATION |
| LTC6908CS6-1#PBF | 制造商:Linear Technology 功能描述:Silicon Oscillator 6-Pin TSOT-23 制造商:Linear Technology 功能描述:OSCILLATOR 10MHZ 5.5V TSOT- 制造商:Linear Technology 功能描述:OSCILLATOR, 10MHZ, 5.5V, TSOT-23-6; Operating Mode:-; Frequency:10MHz; Supply Voltage Min:2.7V; Supply Voltage Max:5.5V; Digital IC Case Style:TSOT-23; No. of Pins:6; Clock External Input:Yes; Operating Temperature Min:0C ;RoHS Compliant: Yes |
| LTC6908CS6-1#TR | 制造商:Linear Technology 功能描述:SC-Timing, 2 Phase 10kHz - 10MHz oscillator W/SSFM |
| LTC6908CS6-1#TRM | 制造商:Linear Technology 功能描述:SC-Timing, 2 Phase 10kHz - 10MHz oscillator W/SSFM |
| LTC6908CS6-1#TRMPBF | 功能描述:IC OSC SILICON 10MHZ TSOT23-6 RoHS:是 类别:集成电路 (IC) >> 时钟/计时 - 可编程计时器和振荡器 系列:- 标准包装:3,000 系列:- 类型:振荡器 - 晶体 计数:- 频率:- 电源电压:2.3 V ~ 5.5 V 电流 - 电源:1.07mA 工作温度:-30°C ~ 80°C 封装/外壳:SOT-665 包装:带卷 (TR) 供应商设备封装:SS迷你型-5D 安装类型:表面贴装 其它名称:AN8955SSMTXLTR |
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