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參數(shù)資料
| 型號(hào)： | MAX2741 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Integrated L1-Band GPS Receiver |
| 中文描述： | 集成L1波段GPS接收機(jī) |
| 文件頁(yè)數(shù)： | 6/12頁(yè) |
| 文件大?。?/td> | 239K |
| 代理商： | MAX2741 |
M
Integrated L1-Band GPS Receiver
6
_______________________________________________________________________________________
The VCO offers a bank of tuning capacitors that can be
latched in/out to adjust the center frequency. Because
the system does not require any RF LO frequency
change (i.e., changing channels), the VCO varactor tun-
ing gain is very low by design, which means the tuning
range of the VCO is narrow. The coarse-tune capacitors
in the tank circuit allow the system to adjust the VCO
center frequency as needed to guarantee that the syn-
thesizer can lock. In practice, process and temperature
effects on VCO centering are negligible, and a coarse-
tune setting of 110 (CONFIG:D7 to D5) will center the
VCO tuning range correctly in virtually all cases. To aid in
bench and prototype testing, the PFD offers out-of-lock-
high and out-of-lock-low indicators, available in the SPI
STATUS register (STATUS:D9 to D8). Use these flags to
determine if the VCO tuning range needs to be adjusted
higher or lower in the case where the PLL cannot lock.
The PLL filter is the only external block of the synthesizer.
The typical filter is a classic C-R-C two-pole shunt network
on the tune line. Low phase noise is preferred at the
expense of longer PLL settling times, so a low 10kHz to
20kHz loop bandwidth is used. The recommended PLL
10kHz filter implementation, with charge pump set to
200μA (CONFIG1:D10 = 1), is shown in Figure 1.
The system/GPS clock is derived either directly from
the reference oscillator, or synthesized from the RFLO
(see the
ADC
section). This clock is used as the sam-
pling clock for the on-chip ADC, and is seen at pin 15,
GPSCLK.
SPI Bus, Address and Bit Assignments
An SPI-compatible serial interface is used to program the
MAX2741 for configuring the different operating modes.
In addition, data can be read out of the MAX2741 for sta-
tus and diagnostic use. The serial interface is controlled
by four signals: SCLK (serial clock),
CS
(chip-select), SDI
(data input), and SDO (data output).
The control of the PLL, AGC, test, offset management,
and block selection is performed through the SPI bus
from the baseband controller. A 20-bit word, with the MSB
(D15) being sent first, is clocked into a serial shift register
when the chip-select signal is asserted low.
The SPI bus has four control lines: serial clock (SCLK),
chip-select (
CS
), data in (SDI), and data out (SDO).
Enable SDO functionality by setting the digital test bus
bits: CONFIG1:D9 to D8 = 01. The timing of the inter-
face signals is shown in Figure 2 and Table 1 along
with typical values for setup and hold time require-
ments.
For best performance, the SPI bus should be configured
during the startup initialization and then left with the opti-
mum values in the registers. Any changes to the ADC
and VGA bits during GPS signal processing may cause
glitches and corrupt the analog signal path. Reading
from the SPI bus does not interrupt GPS operation.
6
V
CC
4
7
GND
8
9
F
S
MAX2741
22nF
36k
100pF
Figure 1. Recommended 3rd-Order PLL Filter
LSB
MSB
CS
SCLK
SDI
t
SETUPD
t
HDATA
t
PERIOD
t
END
t
SETUPSS
Figure 2. SPI Timing Diagram
Table 1. SPI Timing Requirements
SYMBOL
PARAMETER
TYP
VALUE
UNITS
t
SETUPD
t
PERIOD
t
HDATA
t
SETUPSS
t
END
Data to SCLK setup
SCLK period
Data hold to SCLK
CS
to SCLK disable
Falling SCLK to
CS
inactive
20
100
20
20
20
ns
ns
ns
ns
ns
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX2741AETI+ | 功能描述:射頻接收器 Integrated L1-Band GPS Receiver RoHS:否 制造商:Skyworks Solutions, Inc. 類型:GPS Receiver 封裝 / 箱體:QFN-24 工作頻率:4.092 MHz 工作電源電壓:3.3 V 封裝:Reel |
| MAX2741AETI+T | 功能描述:射頻接收器 Integrated L1-Band GPS Receiver RoHS:否 制造商:Skyworks Solutions, Inc. 類型:GPS Receiver 封裝 / 箱體:QFN-24 工作頻率:4.092 MHz 工作電源電壓:3.3 V 封裝:Reel |
| MAX2741AEVKIT | 功能描述:GPS開發(fā)工具 MAX2741A Eval Kit RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Evaluation Boards 工具用于評(píng)估:IT600, STM32F20x 頻率:1.575 GHz 工作電源電壓:1.8 V 接口類型:Wireless |
| MAX2741ETI | 功能描述:射頻接收器 RoHS:否 制造商:Skyworks Solutions, Inc. 類型:GPS Receiver 封裝 / 箱體:QFN-24 工作頻率:4.092 MHz 工作電源電壓:3.3 V 封裝:Reel |
| MAX2741ETI+ | 功能描述:射頻接收器 Integrated L1-Band GPS Receiver RoHS:否 制造商:Skyworks Solutions, Inc. 類型:GPS Receiver 封裝 / 箱體:QFN-24 工作頻率:4.092 MHz 工作電源電壓:3.3 V 封裝:Reel |
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