Rainbow Electronics MAX7057 - Manual (Page 16)

MAX7057
These values are internally summed with 16, and thus,
the min and max divider becomes approximately 19
and 28. These limits MUST be followed, to prevent the
delta-sigma number generator from overflowing. Whenever all of the fhi[11:0] and flo[11:0] are zero, only
an integer divider is used, and the delta-sigma modula-
tor is not in operation. This allows lower current opera-
tion. The 600kHz PLL bandwidth could be used in this
mode to reduce phase noise.
300MHz to 450MHz Frequency-Programmable
ASK/FSK Transmitter
16 ______________________________________________________________________________________
BIT NAME FUNCTION
0 fload
Effectively changes the PLL frequency to the ones written in registers 2–5. This is a self-reset bit,
and is reset to zero after the operation is completed.
Table 12. Frequency Load Register (Address: 0x06)
BIT NAME FUNCTION
0 datain_bit
SPI equivalent of DIN, where the transmitted data can be controlled through the SPI interface. It
should be kept low (0) if only the external DIN pin is used. The external DIN pin should also be kept
low (0) if the SPI datain_bit is used.
Table 13. Data In Register (Address: 0x07)
BIT NAME FUNCTION
0 enable_bit
SPI equivalent of ENABLE. It should be kept low (0) if the external ENABLE pin is used. The external
ENABLE pin should also be kept low (0) if the SPI enable_bit is used.
Table 14. Enable Register (Address: 0x08)
BIT NAME FUNCTION
2-0 gposel[2:0] 3-bit GPO selector
7-3 RESERVED “0” RESERVED. Set to 0 for normal operation.
Table 15. Configuration 1 Register (Address: 0x09)
DECIMAL BINARY GPO DESCRIPTION
0 000 CKOUT_SDO
Clock/SDO Output. Outputs clock when CS is high and clock output is enabled;
outputs SDO when CS is low.
1 001 SDO SPI Serial Data Output (SDO)
2 010 CKOUT Clock Output
3 011 RESERVED RESERVED
4 100 RESERVED RESERVED
5 101 NoXTAL Internal Crystal Oscillator Status. High means oscillator is NOT in operation.
6 110 TxREADY
Transmitter Ready Status. High means PLL is locked and MAX7057 is ready to
transmit data.
7 111 datain_bit A copy of datain_bit
Table 16. General-Purpose Output Selector (gposel[2:0]) for Configuration 1 Register