LTC5555 datasheet(13/26 Pages) AD

13 / 26 page

LTC5555

Rev. 0

For more information www.analog.com

PIN FUNCTIONS

GND (Pins 1, 8, 14, 15, 16 Exposed Pad Pin 29): Ground.

These pins must be soldered to the RF ground plane on

the circuit board. The exposed pad provides both electri-

cal ground contact and thermal contact to the printed

circuit board.

AI–,AI+(Pins2,3):DifferentialIFAttenuatorInputs.These

pins are internally biased to VCC/2 when VCC is applied.

Therefore, a series DC-blocking capacitor must be used.

EN (Pin 4): Enable Control Pin. A CMOS logic high will

enable the IC. This pin has an internal 330k pull-down

resistor, so if unconnected, the IC will be disabled.

VCC(Pin5):PowerSupplyPin.Thispinmustbeconnected

to a regulated 3.3V supply with a bypass capacitor located

close to the pin. Typical DC current consumption is 41mA.

The Supply voltage on this pin defines the logic levels for

the EN and PS pins.

MO+, MO– (Pins 6, 7): Mixer Open-Collector Differential

IF Outputs. These pins must be connected to VCC through

pull-up inductors or transformer windings. Typical DC

current is 27mA into each pin.

RF (Pin 9): Single-Ended RF Input. This pin is internally

biased to VCC/2 when VCC is applied. Therefore, a series

DC-blocking capacitor must be used.

CSB (Pin 10): Serial Port Chip Select and Parallel Data

Latch. In serial control mode this CMOS input allows serial

port communication when driven low and ends the burst

when taken back high. In parallel mode, a rising edge on

this pin loads the parallel data on pins 17 – 21 into the

internal data latch. See the Applications Information sec-

tion for more details.

CLK (Pin 11): Serial Port Clock. This CMOS input clocks

serial port input data on its rising edge. See the Applica-

tions Information section for more details. This pin is

inactive when PS is high.

SDI (Pin 12): Serial Port Data Input. This CMOS input

is used to load serial data into the 8-bit register. See Ap-

plications Information section for more details. This pin

is inactive when PS is high.

SDO (Pin 13): Serial Port Data Output. This CMOS tri-state

output presents data from the serial port during a read

communicationburst.Optionally,attacharesistorof>200k

to GND to prevent a floating output. See the Applications

Information section for more details. This pin is inactive

when PS is high.

D4, D3, D2, D1, D0 (Pins 17 – 21): Parallel Control Pins

for Gain. These CMOS inputs control the IF DVGA gain

when the CSB pin transitions from low to high. The gain

may also be controlled through the serial port when PS is

low. For serial only control, it is recommended that these

pins be grounded.

PS (Pin 22): Parallel Select Pin. A CMOS logic high will

enable IF DVGA control using the parallel data pins (pins

17 – 21). A CMOS logic low allows the SPI port to control

the gain while ignoring the voltages on the parallel data

pins. This pin has an internal 330k pull-down resistor.

RP (Pin 23): Reduced Power Select Pin. A CMOS logic

low on this pin sets the IC to full power mode, unless

programmed to reduced power mode by the SPI. A CMOS

logic high programs the IC to reduced power mode,

independent of the SPI. This pin has an internal 330k

pull-down resistor.

LO–, LO+ (Pins 24, 25): Differential Local Oscillator Input.

These pins are internally connected to ESD diodes to

ground. Therefore, series DC-blocking capacitors must be

used if the LO source has a DC voltage present. Single-

ended or differential drive may be used. Each pin is inter-

nally matched to 50Ω, even when the mixer is disabled.

VDD (Pin 26): Power Supply Pin for SPI and Parallel Inter-

face Logic. This pin must be connected to a regulated 1.8V

to 3.3V supply. Typical DC current consumption is less

than 1mA with CSB low and the clock running at 10MHz.

Whenidle,typicalcurrentconsumptionislessthan500μA.

The Supply voltage on this pin defines the logic levels for

the SPI I/O pins (CSB, CLK, SDI, and SDO), the parallel

data pins (D0 − D4) and the RP pin.

IF–, IF+ (Pins 27, 28): Open Collector Differential IF Buf-

fer Output. These pins must be connected to VCC through

pull-up inductors. Typical DC current is 48mA per pin.

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