MAX2117 데이터 시트보기 (PDF) - Maxim Integrated

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MAX2117

Complete, Direct-Conversion Tuner for MMDS Applications

Maxim Integrated 

Complete, Direct-Conversion Tuner for

MMDS Applications

3-Bit ADC

The MAX2117 has an internal 3-bit ADC connected to

the VCO tune pin (VTUNE). This ADC can be used for

checking the lock status of the VCOs.

Table 15 summarizes the ADC trip points, and the VCO

lock indication. The VCO autoselect routine only selects

a VCO in the “VAS locked” range. This allows room for

a VCO to drift over temperature and remain in a valid

“locked” range.

The ADC must first be enabled by setting the ADE bit in

the VCO register. The ADC reading is latched by a sub-

sequent programming of the ADC latch bit (ADL = 1).

The ADC value is reported in the Status Byte-2 register

(see Table 13).

Table 15. ADC Trip Points and Lock Status

ADC[2:0]

000

001

010

101

110

111

LOCK STATUS

Out of Lock

Locked

VAS Locked

VAS Locked

Locked

Out of Lock

Standby Mode

The MAX2117 features normal operating mode and

standby mode using the I2C interface.

Setting a logic-high to the STBY bit in the Control register

puts the device into standby mode, during which only the

2-wire-compatible bus, the crystal oscillator, the XTAL

buffer, and the XTAL buffer divider are active.

In all cases, register settings loaded prior to entering

shutdown are saved upon transition back to active

mode. Default register values are provided for the

user’s convenience only. It’s the user’s responsibility to

load all the registers no sooner than 100µs after the

device is powered up.

Layout Considerations

The MAX2117 EV kit serves as a guide for PCB

layout. Keep RF signal lines as short as possible to mini-

mize losses and radiation. Use controlled impedance on

all high-frequency traces. For proper operation, the

exposed paddle must be soldered evenly to the board’s

ground plane. Use abundant vias beneath the exposed

paddle for maximum heat dissipation. Use abundant

ground vias between RF traces to minimize undesired

coupling. Bypass each VCC pin to ground with a 1nF

capacitor placed as close as possible to the pin.

18 ______________________________________________________________________________________

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