SY88803VKC TR Micrel Inc, SY88803VKC TR Datasheet - Page 5

• Manufacturer Part Number: SY88803VKC TR
• Description: IC AMP POST PECL 3.3V/5V 10-MSOP
• Manufacturer: Micrel Inc
• Type: Limiting Postamplifierr

Specifications of SY88803VKC TR

• Applications: Optical Networks
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: SY88803VKCTR; SY88803VKCTR

Micrel, Inc
from a single +3.3V or +5V power supply, over temperatures
from –40 C to +85 C. Signals with data rates up to 155Mbps
and as small as 5mV
the allowed input voltage swing. The SY88803V generates
an LOS output. LOS
amplitude detection.
Input Amplifier/Buffer
input stage. The high-sensitivity of the input amplifier allows
signals as small as 5mV
The input amplifier allows input signals as large as
1800mV
38dB differential voltage gain. Since it is a limiting amplifier,
the SY88803V outputs typically 1500mV
waveforms for input signals that are greater than 18mV
Applications requiring the SY88803V to operate with high-
gain should have the upstream TIA placed as close as
possible to the SY88803V’s input pins to ensure the best
performance of the device.
Output Buffer
50 lines. The output buffer requires appropriate termination
for proper operation. An external 50
for each output pin provides this. Figure 3 shows a simplified
schematic of the output stage and includes an appropriate
termination method.
Loss-of-Signal
recommended 2.5k
proper operation, as shown in Figure 4. LOS is used to
determine that the input amplitude is too small to be
considered a valid input. LOS asserts high if the input
amplitude falls below the threshold set by LOS
deasserts low otherwise. LOS can be fed back to the enable
(/EN) input to maintain output stability under a loss of signal
condition. /EN deasserts the true output signal without
removing the input signals. Typically 4.6dB LOS hysteresis
is provided to prevent chattering.
M9999-051706
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DETAILED DESCRIPTION
The SY88803V low-power limiting post-amplifier operates
Figure 2 shows a simplified schematic of the SY88803V's
The SY88803V’s PECL output buffer is designed to drive
The SY88803V generates a chatter-free TTL LOS. A
PP
. Input signals are linearly amplified with a typically
PP
LVL
pullup resistor to V
can be amplified. Figure 1 shows
PP
sets the sensitivity of the input
to be detected and amplified.
resistor to V
PP
CC
voltage-limited
is required for
LVL
CC
–2V
and
PP
.
5
Loss-of-Signal Level Set
the threshold of the input amplitude detection. Setting a
voltage on LOS
threshold. If desired, a resistor divider between V
V
The smaller the voltage difference from LOS
smaller the LOS sensitivity. Hence, larger input amplitude is
required to deassert LOS. “Typical Operating Characteristics”
shows the relationship between the input amplitude detection
sensitivity and the LOS
Hysteresis
hysteresis. By definition, a power ratio measured in dB is
10log(power ratio). Power is calculated as V
electrical signal. Hence the same ratio can be stated as
20log(voltage ratio). While in linear mode, the electrical
voltage input changes linearly with the optical power and
hence the ratios change linearly. Therefore, the optical
hysteresis in dB is half the electrical hysteresis in dB given
in the datasheet. The SY88803V provides typically 2.3dB
LOS optical hysteresis. As the SY88803V is an electrical
device, this datasheet refers to hysteresis in electrical terms.
With 6dB LOS hysteresis, a voltage factor of two is required
to assert or deassert LOS.
REF
A programmable loss-of-signal level set pin (LOS
The SY88803V provides typically 4.6dB LOS electrical
, as shown in Figure 5, also creates this threshold.
LVL
between V
LVL
voltage.
CC
and V
LVL
REF
2
IN
to V
SY88803V
/R for an
sets this
LVL
CC
CC
) sets
, the
and