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參數(shù)資料
| 型號： | TRF3750IRGPRG4 |
| 廠商： | Texas Instruments |
| 文件頁數(shù)： | 18/37頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC PLL FREQ SYNTHESIZER 20-QFN |
| 標(biāo)準(zhǔn)包裝： | 1,000 |
| 類型： | PLL 頻率合成器 |
| PLL： | 無 |
| 輸入： | 時鐘 |
| 輸出： | 時鐘 |
| 電路數(shù)： | 1 |
| 比率 - 輸入:輸出： | 2:1 |
| 差分 - 輸入:輸出： | 是/無 |
| 頻率 - 最大： | 2.4GHz |
| 除法器/乘法器： | 是/無 |
| 電源電壓： | 3 V ~ 5.5 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 20-VFQFN 裸露焊盤 |
| 供應(yīng)商設(shè)備封裝： | 20-QFN 裸露焊盤（4x4） |
| 包裝： | 帶卷 (TR) |
| 配用： | TRF3750T-1900EVM-ND - TRF3750T-1900EVM TRF3750Q1900EVM-ND - TRF3750Q1900EVM 296-20836-ND - EVALUATION MOD FOR CDCM7005-QFN 296-20835-ND - EVALUATION MOD FOR CDCM7005-BGA 296-20834-ND - EVALUATION MOD FOR CDC7005-QFN |
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TRF3750
SLWS146B MARCH 2004 REVISED AUGUST 2007
www.ti.com
25
APPLICATION INFORMATION
SYNTHESIZING A SELECTED FREQUENCY
The TRF3750 is an integer-N PLL synthesizer, and because of its flexibility (14-bit R, 6-bit A, 13-bit B counter,
and dual modulus prescaler), is ideal for synthesizing virtually any desired frequency. Let us assume that we
need to synthesize a 900-MHz local oscillator, with spacing capability (minimum frequency increment) of 200
kHz, as in a typical GSM application. The choice of the external reference oscillator to be used is beyond the
scope of this section, but assuming that a 10-MHz reference is selected, we calculate the settings that yield
the desired output frequency and channel spacing. There is usually more than one solution to a specific set of
conditions, so below is one way of achieving the desired result.
First, select the appropriate R counter value. Since a channel spacing of 200 kHz is desired, the PFD can also
be set to 200 kHz. Calculate the R value through R = REFIN/PFD = 10 MHz / 200 kHz = 50. Assume a prescaler
value of 8/9 is selected. This is a valid choice, since the prescaler output will be well within the 200-MHz limit
(900 MHz / 8 = 112.5 MHz). Select the appropriate A and B counter values. We know that RFOUT = fPFD x N
= (fREFIN / R) x (A + P x B). Therefore, we need to solve the following equation:
900 MHz = 200 kHz x (A + 8 x B)
Clearly there are many solutions to this single equation with two unknowns; there are some basic constraints
on the solution, since 3 ≤ B ≤ 8191, and also B ≥ A. So, if we pick A = 4, solving the equation yields B = 562.
Thus, one complete solution would be to choose: R = 50, A = 4, B = 562, and P = 8/9, resulting in the desired
N = 4500.
The GUI software accompanying the evaluation board of the TRF3750 includes an easy Parameter Selection
Assistant that can directly propose appropriate values for all the counters given the user’s requirements. In
addition, the software can configure all the possible settings of the TRF3750 and can output the data stream
required, so that the user has a reference when programming the serial port.
To complete the example, the serial port has to be programmed in order for the correct frequency to appear
at the output of the complete PLL. Assuming that the user wanted to program the same modes as used in the
RF Performance Specifications section, a possible sequence of serial data going into the device could be the
one listed below for the three different latches (note that the initialization latch is not used in this example):
Table 10. R Counter Latch Programming Example
DB
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DB
10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0
1
0
1
0
1
0
1
0
Table 11. N Counter Latch Programming Example
DB
23
DB
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10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0
1
0
1
0
1
0
1
0
1
Table 12. Function Latch Programming Example
DB
23
DB
22
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10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0
1
0
1
0
1
0
1
0
1
0
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TRF3750Q1900EVM | 功能描述:射頻開發(fā)工具 TRF3750Q1900 Eval Mod RoHS:否 制造商:Taiyo Yuden 產(chǎn)品:Wireless Modules 類型:Wireless Audio 工具用于評估:WYSAAVDX7 頻率: 工作電源電壓:3.4 V to 5.5 V |
| TRF3750Q2100EVM | 制造商:Texas Instruments 功能描述:TRF3750Q2100 EVAL - Bulk |
| TRF3750Q900EVM | 制造商:Texas Instruments 功能描述:TRF3750Q900 EVAL - Bulk |
| TRF3750T-1900EVM | 功能描述:射頻開發(fā)工具 TRF3750T-1900 Eval Mod RoHS:否 制造商:Taiyo Yuden 產(chǎn)品:Wireless Modules 類型:Wireless Audio 工具用于評估:WYSAAVDX7 頻率: 工作電源電壓:3.4 V to 5.5 V |
| TRF3761 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:INTEGER-N PLL WITH INTEGRATED VCO |
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