SL1935
Bit1(POR)isthepower-on resetindicator, andthisisset
The STOP condition can be generated after any data
byte, if however it occurs during a byte transmission, the
previous byte data is retained. To facilitate smooth fine
tuning, the frequency data bytes are only accepted by
the device after all 15 bits of frequency data have been
received, or after the generation of a STOP condition.
to a logic ‘1’ if the Vccd supply to the device has dropped
o
below3V(at25 C),e.g. whenthedevice isinitiallyturned
ON. The POR is reset to ‘0’ when the read sequence is
terminatedby a STOP command. When POR is set high
this indicates that the programmed information may
have been corrupted and the device reset to the power
up condition.
Read mode
Bit 2 (FL) indicates whether the synthesiser is phase
locked, a logic ‘1’ is present if the device is locked, and
a logic ‘0’ if the device is unlocked.
When the device is in read mode, the status byte read
from the device takes the form shown in Table 9b.
Table 2. Programmable Features
Programmable features
Function
Function as described above
Function as described above.
Function as described above.
Synthesiser programmable divider
Reference programmable divider
Baseband filter path select
Local oscillator select
Function as described above.
The charge pump current can be programmed by bits C1 & C0 (Table 5).
The test modes are defined by bits T2 - T0 as described in Table 4.
The general purpose port can be programmed by bit P0;
Logic ‘1’ = on
Charge pump current
Test mode
General purpose port, P0
Logic ‘0’ = off (high impedance)
The buffered crystal reference frequency can be switched to the BUFREF
output by bit RE as described in Table 7. The BUFREF output defaults to
the ‘ON’ condition at device power up.
Buffered crystal reference output,
BUFREF
o
The typical key performance data at Vcc = 5V and +25 C ambient are detailed in Table 1.
Table 3. Reference division ratios
R2
R1
R0
Ratio
R4
R3
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
4
8
16
32
64
128
256
Illegal state
5
10
20
40
80
160
320
Illegal state
6
12
24
48
96
192
384
Illegal state
7
14
28
56
112
224
448
5