LTC5589 datasheet(21/46 Pages) LINER

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LTC5589

5589f

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pin FuncTions

VCTRL (Pin 1): Variable Gain Control Input. This analog

control pin sets the gain. Write a “1” to bit 6 in register

0x01 (AGCTRL = 1) to activate this pin, resulting in about

2.5mA current draw from a positive supply. Typical VCTRL

voltage range is 0.9V to 3.3V. Gain transfer function is

not linear-in-dB. Tie to VCC when not used.

GND (Pins 2, 5, 12, 13, 14, 15, 17, 18, Exposed Pad 25):

Ground. All these pins are connected together internally.

For best RF performance all ground pins should be con-

nected to RF ground.

LOL, LOC (Pins 3, 4): LO Inputs. This is not a differen-

tial input. Both pins are 50Ω inputs. An LC diplexer is

recommended to be used at these pins (see Figure 12).

AC-coupling capacitors are required at these pins if the

applied DC level is higher than ±50mV.

TTCK (Pin 6): Temperature Update. When the TTCK tem-

perature update mode is selected in register 0x01 (bit 7

= High, TEMPUPDT = 1), the temperature readout and

digital gain compensation vs temperature can be updated

through a logic low to logic high transition at this pin. Do

not float.

TEMP (Pin 7): Temperature Sensing Diode. This pin is

connected to the anode of a diode that may be used to

measure the die temperature, by forcing a current and

measuring the voltage. This diode is not part of the on-

chip thermometer.

BBPI,BBMI(Pins8,9):BasebandInputsoftheI-Channel.

The input impedance of each input is about 1kΩ. It should

be externally biased to a 1.4V common mode level, or AC-

coupled.Donotapplycommonmodevoltagebeyond2VDC.

BBPQ, BBMQ (Pins 10, 11): Baseband Inputs of the

Q-Channel. The input impedance of each input is about

1kΩ. It should be externally biased to a 1.4V common

mode level, or AC-coupled. Do not apply common mode

voltage beyond 2VDC. Float if Q-channel is disabled.

RF (Pin 16): RF Output. The output impedance at RF

frequencies is 50Ω. Its DC output voltage is about 1.7V

if enabled. An AC-coupling capacitor should be used at

this pin with a recommended value of 100pF.

CSB (Pin 19): Serial Port Chip Select. This CMOS input

initiates a serial port transaction when driven low, ending

the transaction when driven back high. Do not float.

SCLK (Pin 20): Serial Port Clock. This CMOS input clocks

serial port input data on its rising edge. Do not float.

SDI (Pin 21): Serial Port Data Input. The serial port uses

this CMOS input for data. Do not float.

SDO (Pin 22): Serial Port Data Output. This NMOS output

presentsdatafromtheserialportduringareadtransaction.

Connect this pin to the digital supply voltage through a

pull-up resistor of sufficiently large value, to ensure that

the current does not exceed 10mA when pulled low.

EN (Pin 23): Enable Pin. The chip is completely turned

on when a logic high voltage is applied to this pin, and

completely turned off for a logic low voltage. Do not float.

VCC(Pin24):PowerSupply.Itisrecommendedtouse1nF

and 4.7µF capacitors for decoupling to ground on this pin.

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