参数资料
| 型号： | SY87729LHI |
| 厂商： | Micrel Inc |
| 文件页数： | 17/17页 |
| 文件大小： | 0K |
| 描述： | IC SYNTHESIZER FRACT 3.3V 32TQFP |
| 标准包装： | 250 |
| 系列： | AnyClock® |
| 类型： | 分数合成器 |
| PLL： | 是 |
| 主要目的： | 以太网，光纤通道，SONET/SDH/ATM |
| 输入： | PECL |
| 输出： | PECL |
| 电路数： | 1 |
| 比率 - 输入:输出： | 1:1 |
| 差分 - 输入:输出： | 是/是 |
| 频率 - 最大： | 365MHz |
| 电源电压： | 3.15 V ~ 3.45 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-TQFP 裸露焊盘 |
| 供应商设备封装： | 32-EPAD-TQFP |
| 包装： | 托盘 |
| 配用： | 576-1404-ND - BOARD EVAL N SY87729 EXPERIMENT |
Micrel, Inc.
SY87729L
July 2011
9
M9999-072111-G
hbwhelp@micrel.com
Whereas P sets the integer part of the multiplication
factor from input to output frequency, the control circuit
determines the fractional part. By mixing the output of
the P and P-1 dividers correctly, the control circuit can
fashion any output frequency from P-1 times the input to
P times the input, as long as that ratio can be expressed
as a ratio of integers.
Figure 2. 11/3 Example
Figure 2 shows an example generating an output
frequency 3 times the input frequency. Since the
output frequency is between 3 and 4 times the input, P is
set to 4. We need to select the P divider twice, and
select the P-1 divider once. Multiplying by 4 two times
out of three, and multiplying by 3 one time out of three,
averages to a multiplication of 3.
The top waveform is the reference input. The bottom
waveform is the multiplied output. The waveform in the
middle shows those edges from the output that most
closely matches a corresponding reference waveform
edge.
The control circuit must generate a repeating pattern to
the mux of something like “101,” so that the P divider is
selected twice, and the P-1 divider is selected once,
every three reference edges.
Fractional-N Phase-Frequency Detector
This circuit, besides generating “pump up” and “pump
down” signals, also generates delta phase signals for
use by the lock detect circuit.
This detector circuit also accepts a gating signal from the
Fractional-N control block. When gated, the phase
detector generates neither pump up nor pump down
pulses.
Fractional-N Charge Pump
This circuit converts the “pump up” and “pump down”
signals from the phase-frequency detector into current
pulses. An external loop filter integrates these current
pulses into a control voltage.
Charge pump current is selectable. This modifies loop
gain as follows:
During acquisition of the reference, the charge
pump current is fixed at 20A. Once the
acquisition sequencer has completed center
frequency trimming, then it changes the current
of this charge pump to 50A.
Fractional-N VCO
This circuit converts the voltage integrated by the
external loop filter into a digital clock stream. The
frequency of this clock varies based on this control
voltage. This VCO has a coarse and a fine input, with a
combined range of 540MHz to 729MHz. The coarse
input trims the VCO, as described below, so that its
center frequency rests near the target frequency to
generate. The fine adjustment forms part of the closed
loop. VCO gain is nominally 200MHz per volt.
Fractional-N P/P-1 Divider
This is the main divider for the fractional-N loop. The
logical value of the output of the control block (Figure 1)
defines whether the divider divides by P (values shown
in Table 1) or by P-1. The expression for the fractional
division becomes:
Fractional Division = P
± ()
+
±
P
Q
1
P
Q
1
P
Q
Where QP is the number or reference clock periods
during which the divider must divide by P and QP–1 is the
number of reference clock periods during which the
divider must divide by P-1.
or (408) 955-1690
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SY87729LHI-EVAL | 功能描述:BOARD EVAL N SY87729 EXPERIMENT RoHS:是 类别:编程器，开发系统 >> 评估演示板和套件 系列:SuperCOM™ 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- 主要目的:电源管理，电池充电器 嵌入式:否 已用 IC / 零件:MAX8903A 主要属性:1 芯锂离子电池 次要属性:状态 LED 已供物品:板 |
| SY87729LHITR | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:3.3V AnyClock (10MHz to 365MHz) FRACTIONAL N SYNTHESIZER |
| SY87729LHY | 功能描述:时钟合成器/抖动清除器 3.3V Fractional N Synthesizer (10MHz to 365MHz) (Lead Free/I Temp/32 pin TQFP) RoHS:否 制造商:Skyworks Solutions, Inc. 输出端数量: 输出电平: 最大输出频率: 输入电平: 最大输入频率:6.1 GHz 电源电压-最大:3.3 V 电源电压-最小:2.7 V 封装 / 箱体:TSSOP-28 封装:Reel |
| SY87729LHY TR | 功能描述:时钟合成器/抖动清除器 3.3V Fractional N Synthesizer (10MHz to 365MHz) (Lead Free/I Temp/32 pin TQFP) RoHS:否 制造商:Skyworks Solutions, Inc. 输出端数量: 输出电平: 最大输出频率: 输入电平: 最大输入频率:6.1 GHz 电源电压-最大:3.3 V 电源电压-最小:2.7 V 封装 / 箱体:TSSOP-28 封装:Reel |
| SY87729LHYTR | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:3.3V AnyClock (10MHz to 365MHz) FRACTIONAL N SYNTHESIZER |
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