MAX3544 Просмотр технического описания (PDF) - Maxim Integrated

Номер в каталоге

Компоненты Описание

производитель

MAX3544

Multiband Digital Television Tuner

Maxim Integrated 

Multiband Digital Television Tuner

Table 23. R13: BIAS ADJ Register—Bias Adjustments (Address: 13h) (continued)

BIT NAME

BIT LOCATION

(0 = LSB)

TYPICAL

SETTING

FUNCTION

MIXB[1:0]

3:2

Mixer bias.

00 = Unused

01

01 = Nominal setting

10 = Unused

11 = Highest linearity setting

FILTB

1

IFVGAB

0

1

Must set to 1 for proper operation

IF VGA bias.

0

0 = Default

1 = Highest current (approximately nominal + 6mA)

Note: Only production tested and guaranteed functional in state 0XX1 X11X, where X can be either 1 or 0. All other states are

untested and may not function correctly. Contact Maxim if untested settings will be used in production.

Table 24. R14: TEST1 Register (Address: 14h)

BIT NAME

BIT LOCATION

(0 = LSB)

TYPICAL

SETTING

FUNCTION

RESERVED

7:0

0100

0000

Must set to 0100 0000 for proper operation

Note: This register is not available to the end user.

Table 25. R15: ROM WRITE DATA Register (Address: 15h)

BIT NAME

BIT LOCATION

(0 = LSB)

TYPICAL

SETTING

ROMW[7:0]

7:0

N/A

Maxim use only

Note: This register is not available to the end user.

FUNCTION

Applications Information

RF Inputs and Filters

The MAX3544 features separate low- and high-frequency

inputs. These two inputs are combined to a single input

by an off-chip diplexer circuit as shown in the Typical

Application Circuit. When the desired channel is less

than 345MHz, use RFINL. When the desired input is

greater than 345MHz, use RFINH. Further, when the

desired input is less than 110MHz, an internal lowpass

filter should be enabled to limit high-frequency interfer-

ence incident at the mixer input. The lowpass filter is

enabled by the RFLPF bit in R05[5].

Besides selecting the appropriate input port and setting

RFLPF appropriately, one of three tracking filters must

be chosen based on the desired frequency. Set TFB

(R05[3:2]) to select VHFL, VHFH, or UHF tracking filter

bands. Use VHFL when the desired frequency is less

than 196MHz, use VHFH when the desired frequency

is between 196MHz and 440MHz, or use UHF when the

desired frequency is greater than 440MHz.

RF Gain Control

The MAX3544 is designed to control its own RF gain

based on internally measured signal and blocker levels.

The user can adjust the AGC attack points (takeover

points) by setting WDPA and NDPA in register R0B.

Alternatively, the user can control the RF gain by driving

the RFVGC input pin.

______________________________________________________________________________________   17

Share Link: