ML5800

DS5800-F-04

FINAL DATASHEET

JULY 2006

17

TRANSMIT & RECEIVE DATA INTERFACES

There are two sets of transmit and receive data interfaces for the ML5800:

Baseband Data:

DIN, DOUT, AOUT

RF Data:

RXI, TXO

BASEBAND DATA: DIN, DOUT, AOUT

The DIN pin is a CMOS-level serial data input for FSK modulation on the radio channel. This DIN pin drives data bits

into the two-port transmit modulator. When used with Direct Sequence Spread Spectrum (DSSS), the chip rate, bit rate

and spreading code are determined in the baseband processor and the FM deviation and transmit filtering are

determined in the ML5800. There is no re-timing of the chips, so the transmitted FSK chips take their timing from the

data on this pin.

The DOUT pin is a corresponding CMOS-level digital data output. The data on this pin is valid only when the run length

of the transmitted digital data is limited to consecutive 1’s or 0’s no longer than 3

μs.

When longer run lengths are used, an off-chip data slicer is required, driven from the AOUT_TPC pin. Setting the AOUT

bit in Register 0 turns the AOUT_TPC pin into a buffered, single-ended analog output from the data filter. This output

can be used to drive an off-chip data slicer or an ADC input for a DSP data slicer. Clock recovery for both DOUT and

AOUT modes is performed in the baseband.

RF DATA: RXI, TXO

The RXI receive input (pin 20) and the TXO transmit output (pin 21) are the only RF I/O pins. The RXI pin requires a

simple impedance matching network for best input noise figure, and the TXO pin also requires a matching network for

maximum power output into 50

Ω. The voltage on the modulation port swings above and below its central value to

produce 2-FSK modulation on the VCO (See Figure 6).

For best performance, all RF ground pins must have a direct connection to the RF ground plane, and the RF supply

pins must be well decoupled from the RF ground pins.

TRANSIENT TRANSMIT MODULATION

Freq=5.779456GHz, VCCA=VDD=3.3V, Ta=25C

NAME

DESCRIPTION

CONDITIONS

MIN

TYP

MAX

Units

Final Modulation Deviation

After 200us of consecutive 1 or 0

bits

±500

±512

±524

kHz

Maximum Modulation

Deviation

PN (15 bit) Sequence Encoded

Data @ 1.536Mb/s

±720

kHz

Minimum Modulation

Deviation

PN (15 bit) Sequence Encoded

Data @ 1.536Mb/s

±450

kHz

Modulation center frequency

offset

50us after RXON low

±50

kHz

Figure 6. Transient Transmit Modulation Waveform