March 1997
ML4632
Fiber Optic LED Driver
GENERAL DESCRIPTION
The ML4632 is a fiber optic LED driver suited for network
applications up to 20Mbps. The part is capable of driving
up to 100mA of current through a Fiber Optic LED from
an ECL or TTL level input signal. Its efficient output stage
provides a high current that can be programmed for
accurate absolute output level as well as automatic
temperature compensation. The combination of automatic
temperature compensation and a highly accurate current
driven design insures precise launch power.
The LED driver’s output stage provides fast, well matched
rise and fall times through a unique class B output stage
that burns supply current only when the LED is on. A
positive temperature coefficient of up to 3300ppm/°C can
be programmed into the output current to compensate for
the negative temperature coefficient of the LED optical
output power. An optional peaking circuit may also be
employed.
The ECL and TTL inputs are ANDed so one can be used
for data and the other for an enable input. An ECL
compatible BIAS voltage is also provided for single ended
ECL applications.
FEATURES
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Current Driven Output for accurate Launch Power
Programmable output current from 20mA to 100mA
Programmable temperature coefficient, 0 to 3300ppm/°C
High Efficiency Output Stage
Programmable LED pre-bias current
Low EMI/RFI Noise
ECL or TTL inputs
Optional Peaking circuit
APPLICATIONS
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IEEE 802.3, 10BASE-F
IEEE 802.5 Fiber Optic Token Ring
IEEE 802.4 Fiber Optic Token Bus
Fiber Optic Data Communications and
Telecommunications
BLOCK DIAGRAM
ECLP 14
ECLN
1
+
BUFFER
–
PEAK
7
PEAK
6
RPK
VBIAS
2
3
LED
DRIVER
5
RTSET
TTL 13
V
CC
8
DRV
AMP
REF
PTAT
11 DRV
10 VREF
12 PTAT
GND
4
9
I
OFF
1
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
