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参数资料
| 型号： | LTC6909HMS#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 模拟信号调理 |
| 英文描述： | SPECIALTY ANALOG CIRCUIT, PDSO16 |
| 封装： | LEAD FREE, PLASTIC, MSOP-16 |
| 文件页数： | 21/22页 |
| 文件大小： | 0K |
| 代理商： | LTC6909HMS#PBF |
LTC6909
8
6909fa
IRES (A)
V RES
=
V
+ –
V
SET
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.1
10
100
1000
6909 F01
1
V+ = 5V
V+ = 3V
TA = 25°C
As shown in the Block Diagram, the LTC6909’s master
oscillator is controlled by the ratio of the voltage between
the V+A and SET pins and the current entering the SET pin
(IMASTER). When the spread spectrum frequency modula-
tion (SSFM) is disabled, IMASTER is strictly determined by
the (V+A – VSET)voltageandtheRSETresistor.WhenSSFM
is enabled, IMASTER is modulated by a filtered pseudoran-
dom noise (PRN) signal. Here the IMASTER current is a
random value uniformly distributed between (ISET – 10%)
and (ISET + 10%). In this way, the frequency is modulated
to produce an approximately flat frequency spectrum,
centered about the set frequency with a bandwidth equal
to approximately 20% of the center frequency.
The voltage on the SET pin is forced to approximately 1.1V
below V+A by the PMOS transistor and its gate bias volt-
age. This voltage is accurate to ±5% at a particular input
current and supply voltage (see Figure 1). The LTC6909
is optimized for use with resistors between 20k and 400k
corresponding to master oscillator frequencies between
500kHz and 10MHz. Accurate master oscillator frequen-
cies up to 20MHz (RSET = 10k) are attainable if the supply
voltage is greater than 4V. The RSET resistor, connected
between the V+A and SET pins, locks together the (V+A –
VSET) voltage and the current ISET. This allows the parts
to attain excellent frequency accuracy regardless of the
precisionoftheSETpin.Themasteroscillationfrequencyis:
fMASTER = 20MHz 10k/RSET
Figure 1. V+ – VSET Variation with IRES
When the spread spectrum frequency modulation (SSFM)
is disabled, the master oscillator frequency is stationary.
When SSFM is enabled, the master oscillator frequency
varies from 0.9 fMASTER to 1.1 fMASTER.
Output Frequency and Configurations
The output frequency of the LTC6909 is set by the RSET
resistor value and the connections of the PH0, PH1 and
PH2 logic input pins. The following formula defines the
relationship:
fOUT = 20MHz 10k/(RSET PH)
where PH = 3, 4, 5, 6, 7 or 8 and is defined as follows:
PH2
PH1
PH0
MODE
0
All Outputs Are Floating (Hi-Z)
0
1
All Outputs Are Held Low
0
1
0
3-Phase Mode (PH = 3)
0
1
4-Phase Mode (PH = 4)
1
0
5-Phase Mode (PH = 5)
1
0
1
6-Phase Mode (PH = 6)
1
0
7-Phase Mode (PH = 7)
1
8-Phase Mode (PH = 8)
The PH0, PH1 and PH2 pins are standard logic input pins.
These pins do not have any active pull-up or pull-down
circuitry. As such, they cannot be left floating and must be
connected to a valid logic high or low voltage. The PH0,
PH1 and PH2 pin connections not only divide the master
oscillator frequency by the value PH but also determine
the phase relationship between the output signals. Figure
2 shows the output waveforms for each of the eight pos-
sible output configurations.
Note that 2-phase, complementary (180° phase shifted)
outputs are available in the 4-, 6- and 8-phase modes
by choosing the correct pair of signals. For example, in
4-phase mode, OUT1 and OUT3 (or OUT2 and OUT4) are
complementary.
operAtion
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC6909HMS-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation |
| LTC6909IMS#PBF | 功能描述:IC OSC SILICON 6.67MHZ 16-MSOP 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 |
| LTC6909IMS#TRPBF | 功能描述:IC OSC SILICON 6.67MHZ 16-MSOP 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:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:45 系列:- 类型:温度 - 补偿晶体振荡器（TCXO） 计数:- 频率:25MHz 电源电压:3.135 V ~ 3.465 V 电流 - 电源:1.5mA 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 包装:管件 供应商设备封装:16-SOIC W 安装类型:表面贴装 |
| LTC6909IMS-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation |
| LTC6909IMS-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation |
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