MAX2771ETI+ datasheet, price, pdf

MAX2771ETI+ Pinout Equivalent Circuit

MAX2771ETI+ is a multi band universal GNSS receiver launched by Analog Devices.This chip supports global navigation satellite systems such as GPS,Galileo,GLONASS,BeiDou,IRNSS, QZSS, and SBAS,and can cover multiple frequency bands such as E1/L1,L2,L5, E5,E6,B1,B2,B3, etc. The chip integrates a complete receiving link internally, including a dual input low-noise amplifier(LNA), mixer, internal single-chip filter, programmable gain amplifier(PGA),multi bit analog-to-digital converter(ADC), and crystal oscillator circuit.Its total cascaded noise figure can reach a minimum of 1.4dB,and it can provide a cascaded gain of up to 110 dB and a gain control range of 59dB.Due to the high integration level of the chip,only a small number of peripheral components are needed.
MAX2771ETI+adopts QFN-28-EP (5×5), and its pin functions can be roughly divided into RF front-end, digital interface, PLL and clock, power supply and control modules. The following table lists some of the main pins and their functional descriptions:

Alternative model selection:

Due to the high integration and strong performance of MAX2771ETI+in the field of multi frequency GNSS reception, there are almost no substitute models that can fully match it. However, if only partial similarity in functionality and interface is required, and partial substitution of lower level products is needed, the following are several products that are similar to MAX2771ETI+in certain key parameters:

Picture	Name	Constellation Support	Noise Figure	Package
	MAX2769C	GPS/GLONASS/Galileo/Beidou System	1.4 dB	QFN-28-EP (5×5)
	MAX2769	GPS/GLONASS/Galileo	1.4 dB	QFN-28-EP (5×5)
	MAX2769B	GPS/GLONASS/Galileo/Beidou System	1.4 dB	QFN-28-EP (5×5)

Application circuit and precautions:

In most cases, the GNSS front-end circuit design with MAX2771ETI+as the core requires external antennas to introduce satellite signals into the high-frequency and low-frequency LNA input terminals through a 50 Ω matching network to ensure maximum signal energy transmission and reduce losses caused by reflection. The power supply usually uses a single power supply (2.7-3.3V), and low ESR ceramic capacitors (usually 100nf) are placed near key pins such as VCCCP, VCCRF, VCCADC, VCCVCO, and VCCD to stabilize power supply and suppress power noise. The external crystal oscillator provides a high-precision, low phase noise reference clock through the XTAL pin, which supplies clock signals to the internal PLL and frequency divider. The chip can communicate data with microcontrollers or FPGA devices through SPI interfaces (CSN, SDATA, SCLK), making it easy to configure registers and collect data. The overall PCB design requires the RF signal path to be as short as possible, the routing impedance to be executed according to requirements, and the analog and digital parts to be completely separated. At the same time, the exposed solder pads should be closely integrated with the large-area ground plane to improve heat dissipation and shielding effects.