max9483cee-t Maxim Integrated Products, Inc., max9483cee-t Datasheet - Page 7

• Manufacturer Part Number: max9483cee-t
• Description: Dual-output, Multimode Cd-rw/dvd Laser-diode Drivers
• Manufacturer: Maxim Integrated Products, Inc.

The MAX9483/MAX9484 high-performance multimode
LDDs are designed for CD and DVD combination pick-
up heads. The drivers have three current channels.
Each channel has a current input IN_ (_ = 1, 2, or 3)
and a channel control signal (ENABLE, NE2, or NE3).
IN1 supplies the reference for the read channel, which
provides the read current or the offset current to the
lasers. The other two channels are the write channels.
The currents of these two channels are superimposed
on the read current that serves as the offset current for
the laser in write mode. The offset current significantly
reduces the laser output ramp-up time. When ENABLE
is low, all three channels are disabled. Driving ENABLE
high enables the read channel and leaves the other two
write channels to be controlled by NE2 and NE3 (see
Figure 1). By selecting the input currents at IN2 and
Figure 1. Timing Diagram of Output vs. Control Signals
ENABLE
I
NE2
NE3
OUT
H
H
H
L
L
L
Read Channel and Write Channels
_______________________________________________________________________________________
t
EN
Detailed Description
t
ON
t
r
CD-RW/DVD Laser-Diode Drivers
t
ON
t
r
Dual-Output, Multimode
IN3, as well as the signal timing of NE2 and NE3, the
drivers can generate various current waveforms for dif-
ferent CD/DVD writing standards. All three channels
have a current gain of 100. The maximum total current
each output can provide is 400mA.
To reduce the laser-mode hopping noise in read mode,
modulate the read current with an oscillator with a
100MHz to 600MHz frequency. An external resistor, RF,
determines the oscillator frequency selection. For the
MAX9484, two external resistors, R
used to select the oscillator frequency for CD and DVD
lasers separately. The swing amplitude of the oscillator
current is set by two external resistors, R
one for CD and one for DVD. The oscillator is enabled
when both ENABLE and ENOSC are driven high.
t
OFF
t
f
t
OFF
t
f
t
DIS
F1
RF Oscillator
and R
S1
and R
TIME
F2
, are
S2
7
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