Datasheet
Laser Driver for Projectors
MAX3600
15
PRBS Oscillator
The PRBS oscillator creates clock f
PRBS1
, which can be
input to the PRBS generator. The oscillator frequency
is determined by the PRBS_N bit setting as shown in
Table 5. The recommended range for f
PRBS1
is 100MHz
to 150MHz. Note that the PRBS oscillator is not phase-
locked to the pixel clock. Therefore, OUT4 updates are
not synchronous to the pixel clock when the PRBS oscil-
lator is used.
PRBS Generator
Output 4 can be used to generate random noise. A
32-bit shift register with feedback generates pseudo-
random codes. The PRBS_SEL bit selects the PRBS
clock source.
Serial Port and Registers
The serial port provides a 3-wire interface with bidirec-
tional data (SDA), clock input (SCL), and a chip-select
input (CS) as shown in Figure 14. Table 6 shows the
register addresses. The external master initiates a data
transfer by asserting the CS pin.
Write Mode (R/W = 0): The master generates 16 clock
cycles. It outputs 16 bits (MSB first) to the SDA line at the
falling edge of the clock. The master ends the transmis-
sion by setting CS high. The laser driver updates control
registers on the rising clock edge of the last data bit.
Read Mode (R/W = 1): The master generates 16 clock
cycles. It outputs 8 bits (MSB first) to the SDA line at the
falling edge of the clock. The SDA line is released after
the R/W bit has been transmitted. The slave outputs 8
bits of data (MSB first) at the rising edge of the clock. The
master ends the transmission by setting the CS pin high.
Read clock speed is determined by the external pullup
resistor and parasitic capacitance at the SDA pin.
Figure 13. PO Subpixels
Table 4. PO Subpixel Programming
Table 5. PRBS Oscillator
VIDEO2
I
OUT2
SUBPIXEL
PO
TIME
PIXEL 2PIXEL 1
PO
START
PO
STOP
11
1
1 mm. ........ .........
t
PIXEL
(ns)
PO_M PRBS_N
SUBPIXELS
(m)
f
PRBS1
(MHz)
10 1 3 16 136
12 1 2 16 125
14 1 0 16 129
16 2 3 24 128
18 2 2 24 125
20 2 1 24 120
22 2 0 24 123
24 3 2 32 125
26 4 3 40 131
28 4 3 40 121
30 4 2 40 125
32 4 1 40 125
34 5 3 48 120
36 5 2 48 125
38 6 3 56 125
40 6 3 56 119
PRBS_N f
PRBS1
/f
PO
0 0.9
1 0.8
2 0.75
3 0.68