MAX3795ETG Maxim Integrated Products, MAX3795ETG Datasheet - Page 10

• Manufacturer Part Number: MAX3795ETG
• Description: Laser Driver 1Gbps to 4.25Gbps Mu ltirate VCSEL Driver
• Manufacturer: Maxim Integrated Products
• Type: Transmitterr

Specifications of MAX3795ETG

• Operating Supply Voltage: 3.3 V
• Package / Case: TQFN-24 EP
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT

1Gbps to 4.25Gbps Multirate VCSEL Driver
with Diagnostic Monitors
The modulation circuitry consists of an input buffer, a
current mirror, and a high-speed current switch (Figure
3). The modulator drives up to 15mA of modulation into
a 50Ω VCSEL load.
Table 2. Circuit Response to Various Single-Point Faults (Closed-Loop APC Configuration)
*A fault state asserts the FAULT pin, disables the modulator output, and disables the bias output.
10
TX_DISABLE
PIN NAME
SQUELCH
BIASMON
PEAKSET
PWRMON
MODSET
BIASSET
FAULT
COMP
OUT+
OUT-
______________________________________________________________________________________
BIAS
TC1
TC2
REF
IN+
MD
IN-
Does not affect laser power.
Modulation and bias current are
disabled.
Does not affect laser power.
Does not affect laser power.
Does not affect laser power.
Does not affect laser power.
The laser modulation is increased,
but average power is not affected.
Modulation current is disabled.
Does not affect laser power.
Modulation current is disabled.
Does not affect laser power.
Laser bias is disabled.
Fault state* occurs. Note that VCSEL
emissions may continue. Care must
be taken to prevent this condition.
Fault state* occurs.
The bias current is reduced, and the
average power of the laser output is
reduced.
I
determined by R
monitor fault threshold is exceeded,
a fault is signaled.
I
determined by R
monitor fault threshold is exceeded,
a fault is signaled.
Fault state* occurs.
BIAS
BIAS
increases to the value
increases to the value
CIRCUIT RESPONSE TO
V
CC
BIASSET
BIASSET
SHORT
Modulation Circuit
. If the bias-
. If the bias-
Does not affect laser power.
Normal condition for circuit
operation.
Does not affect laser power.
Does not affect laser power.
Does not affect laser power.
Does not affect laser power.
Modulation current is disabled.
The laser modulation is increased,
but average power is not affected.
Does not affect laser power.
Modulation current is disabled.
Does not affect laser power.
Fault state* occurs.
This disables the VCSEL.
Does not affect laser power.
I
determined by R
monitor fault threshold is exceeded,
a fault is signaled.
The bias current is reduced, and the
average power of the laser output is
reduced.
The bias current is reduced, and the
average power of the laser output is
reduced.
Does not affect laser power.
BIAS
increases to the value
CIRCUIT RESPONSE TO
GND SHORT
The amplitude of the modulation current is set with
resistors at MODSET and temperature coefficient (TC1,
TC2) pins. The resistor at MODSET (R
grams the temperature-stable portion of the modulation
current, and the resistor between TC1 and TC2 (R
programs the temperature coefficient of the modulation
BIASSET
. If the bias-
Does not affect laser power.
Modulation and bias current are
disabled.
Does not affect laser power.
Does not affect laser power.
Does not affect laser power.
The laser modulation is decreased,
but average power is not affected.
The laser modulation is decreased,
but average power is not affected.
The laser modulation is decreased,
but average power is not affected.
Does not affect laser power.
Modulation current is disabled.
Does not affect laser power.
Laser bias is disabled.
This disables the VCSEL.
Fault state* occurs.
APC loop will be unstable.
If the bias-monitor fault threshold is
exceeded, a fault is signaled.
I
determined by R
monitor fault threshold is exceeded,
a fault is signaled.
The bias current is reduced, and the
average power of the laser output is
reduced.
Does not affect laser power.
BIAS
increases to the value
CIRCUIT RESPONSE TO
OPEN
BIASSET
MODSET
. If the bias
) pro-
TC
)