9 of 19

RFMD2080

DS140110

7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical

support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.

Hardware Control

Three hardware control pins are provided: ENBL, MODE, and RESETX.

The ENBL pin has two functions: to enable the analog circuits in the chip and to trigger the VCO auto-selection and coarse tun-

ing mechanisms. The VCO auto-selection and coarse tuning are initiated when the ENBL pin is taken high. Every time the fre-

quency of the synthesizer is reprogrammed, ENBL has to be asserted high to initiate these mechanisms and then to initiate the

PLL locking. Alternatively following the programming of a new frequency the PLL re-lock self clearing bit could be used.

If the device is left in the enabled state for long periods, it is recommended that VCO auto-selection and coarse tuning (band

selection) is performed for every 30°C change in temperature. The lock detect flag can be used to indicate when to perform

the VCO calibration; it shows that the VCO tuning voltage has drifted significantly with changing temperature.

The RESETX pin is a hardware reset control that will reset all digital circuits to their startup state when asserted low. The device

includes a power-on-reset function, so this pin should not normally be required, in which case it should be connected to the

positive supply.

The MODE pin controls which PLL programming register bank is active.

Serial Data Interface Control

The normal mode of operation uses the 3-wire serial data interface to program the device registers, and three extra hardware

control lines; MODE, ENBL and RESETX.

When the device is under software control, achieved by setting the SIPIN bit in the SDI_CTRL register high, then the hardware

can be controlled via the SDI_CTRL register. When this is the case, the MODE and ENBL control lines are not required. If the

device is under software control, pins 1 and 9 can be configured as general purpose outputs (GPO).

Multi-Slice Mode

The Multi-Slice mode of operation allows up to four chips to be controlled from a common serial bus. The device address pins,

(15 and 16) ADD1 and ADD2, are used to set the address of each part.

On power up, and after a Reset, the devices ignore the address pins ADD1 and ADD2 and any data presented to the serial bus

will be programmed into all the devices. However, once the 'ADDR' bit in the SDI_CTRL register is set each device then adopts

an address according to the state of the address pins on the device.

General Purpose Outputs

The general purpose outputs (GPOs) can be controlled via the GPO register, and will depend on the state of MODE since they

can be set in different states corresponding to either path 1 or 2. The GPOs can be used for example to drive LEDs, or to con-

trol external circuitry such as switches or low power LNAs.

Slice 2

(0)

Slice2

(1)

Slice2

(2)

Slice2

(3)

A1 A2

ENX

SDATA

SCLK

Vdd

Vdd

Vdd

Vdd

A1 A2

A1 A2

A1 A2