MICREL SY88923 Datasheet
2.5Gbps HIGH-SPEED
LIMITING POST AMPLIFIER
SY88923
FEATURES
■ Up to 2.5Gbps operation
■ Low noise
■ Chatter-Free LOS generation
■ Open Collector TTL LOS output
■ TTL /EN Input
■ Differential PECL inputs for data
■ Single power supply
■ Designed for use with SY88922 and SY88904 or
SY88905
■ Available in a tiny 10-pin (3mm) MSOP
PIN CONFIGURATION
LOS
1/EN
D
IN
2
/D
IN
V
REF
LVL
MSOP
3
K10-1
4
5
10 V
9
8
7
6
CC
D
OUT
/D
OUT
LOS
GND
DESCRIPTION
The SY88923 limiting post amplifier with its high gain
and wide bandwidth is ideal for use as a post amplifier in
fiber-optic receivers with data rates up to 2.5Gbps. Signals
as small as 5mVp-p can be amplified to drive devices with
PECL inputs. The SY88923 generates a chatter-free Loss
of Signal (LOS) open collector TTL output.
The SY88923 incorporates a programmable level detect
function to identify when the input signal has been lost.
This information can be fed back to the /EN input of the
device to maintain stability under loss of signal condition.
Using LOSLVL pin, the sensitivity of the level detection can
be adjusted. The LOSLVL voltage can be set by connecting
a resistor divider between VCC and VREF. Figure 3 and
Figure 4 show the relationship between input level sensitivity
and the voltage set on LOSLVL. Figure 5 shows the
relationship between input level sensitivity and resistor
divider ratio.
The LOS output is a TTL open collector output that
requires a pull-up resistor for proper operation, Figure 1.
+5.0V
SY88923
LOS
2k
APPLICATIONS
■ 1.25Gbps Gigabit Ethernet
■ 531Mbps and 1062Mbps Fibre Channel
■ 622Mbps SONET
■ Gigabit interface converter
■ 2.5Gbps SDH/SONET
Figure 1. LOS Output with Desired Rise Time
BLOCK DIAGRAM
D
IN
Limiting
Amplifer
LOS
D
V
REF
V
CC
GND
LVL
IN
ECL
Buffer
Level
Detect
Enable
D
OUT
D
OUT
EN
LOS
Rev.: C Amendment: /1
1
Issue Date: July 2000
Micrel
SY88923
PIN NAMES
Pin Type Function
DIN Data Input Data Input
/DIN Data Input Inverting Data Input
LOS LVL Input LOS Limit Set
/EN TTL Input Output Enable (Active Low)
LOS TTL Output Loss of Signal Indicator
(Open Collector) (Active High)
GND Ground Ground
/DOUT PECL Output Inverting Data Output
DOUT PECL Output Data Output
VCC Power Supply Positive Power Supply
REF Output Reference Voltage Output for
V
LOS Level Set (see Fig. 3)
ABSOLUTE MAXIMUM RATINGS
Symbol Rating Value Unit
VCC Power Supply Voltage 0 to +7.0 V
DIN, /DIN Input Voltage 0 to VCC V
DOUT, /DOUT Output Voltage (with 50Ω load) VCC –2.5, VCC +0.3 V
TA Operating Temperature Range –40 to +85 °C
store Storage Temperature Range –55 to +125 °C
T
(1)
GENERAL DESCRIPTION
General
The SY88923 is an integrated limiting amplifier intended
for high-frequency fiber-optic applications. The circuit
connects to typical transimpedance amplifiers found within
a fiber-optics link. The linear signal output from a
transimpedance amplifier can contain significant amounts
of noise, and may vary in amplitude over time. The SY88923
limiting amplifier quantizes the signal and outputs a voltagelimited waveform.
The /EN pin allows the user to disable the output signal
without removing the input signal.
NOTE:
1. Permanent device damage may occur if ABSOLUTE MAXIMUM RATINGS are exceeded. This is a stress rating only and functional operation is not implied
at conditions other than those detailed in the operational sections of this data sheet. Exposure to ABSOLUTE MAXIMUM RATlNG conditions for extended
periods may affect device reliability.
2
Micrel
SY88923
DC ELECTRICAL CHARACTERISTICS
VCC = +5V ±10%, RLOAD = 50Ω to VCC-2V, TA = –40°C to +85°C
A = –40°CTA = 0°CTA = +25°CTA = +85°C
T
Symbol Parameter Min. Max. Min. Max. Min. Typ. Max. Min. Max. Unit
(7)
(1)
— 35 — 35 — 21 35 — 35 mA
(8)
–0.3
—20
— 100
GND +2.0 VCC –1.0 GND +2.0 VCC –1.0 GND +2.0 —VCC –1.0 GND +2.0 VCC –1.0
— –0.3
(5)
(6)
(8)
— –0.3
—20
— 100
(5)
(6)
(8)
——20
— — 100
— — –0.3
(5)
(6)
(8)
—20
— 100
VREF VCC VREF VCC VREF —VCC VREF VCC V
(3)
(4)
— 0.5 — 0.5 — — 0.5 — 0.5 V
— 250 — 250 — — 250 — 250 uA
VCC–1085 VCC–880 VCC–1025 VCC–880 VCC–1025 VCC–955 VCC–880 VCC–1025 VCC–880
VCC–1830 VCC–1555 VCC–1810 VCC–1620 VCC–1810 VCC–1705 VCC–1620 VCC–1810 VCC–1620
VCC–2.625 VCC–2.325 VCC–2.625 VCC–2.325 VCC–2.625 VCC–2.475 VCC–2.325 VCC–2.625 VCC–2.325
2.0 — 2.0 — 2.0 — — 2.0 — V
— 0.8 — 0.8 — — 0.8 — 0.8 V
—mA
(5)
(6)
ICC
IIL
IH
I
Power Supply Current
/EN Input LOW Current
/EN Input HIGH Current
VCMR Common Mode Range
Voffset Differential Output Offset — ±100 — ±100 — — ±100 — ±100 mV
LOSLVL LOSLVL Level
(2)
VOL LOS Output Low Level
IOH LOS Output Leakage
OH DOUT and /DOUT
V
HIGH Output
OL DOUT and /DOUT
V
LOW Output
VREF Reference Supply
VIH
V
IL
/EN Input HIGH Voltage
/EN Input LOW Voltage
µA
V
mV
mV
V
NOTES:
1. No output load.
2. 223-1 pattern.
3. IOL = + 2mA.
4. VOH = 5.5V.
5. VIN = 2.7.
6. VIN =VCC.
7. IREF must be limited within –0.8mA (source) and 0.4mA (sink).
8. VIN = 0.5V.
AC ELECTRICAL CHARACTERISTICS
VCC = +5V ±10%, RLOAD = 50Ω to VCC - 2V, TA = –40°C to +85°C
TA = –40°CTA = 0°CTA = +25°CTA = +85°C
Symbol Parameter Min. Max. Min. Max. Min. Typ. Max. Min. Max. Unit Conditions
PSRR Power Supply
(1)
Rejection Ratio 55MHz
VID Input Voltage Range 5 1800 5 1800 5 — 1800 5 1800 mVp-p
r, tf Output Rise/Fall Time — 175 — 175 — — 175 — 175 ps VID > 100mVp-p
t
OD Differential Output — — — — — 600 — — — mV VID = 15mVp-p
V
Voltage Swing
t
OFFL LOS Release Time
(2)
(3)
Minimum Input
OFFH LOS Release Time
t
(4)
Maximum Input
tONL LOS Assert Time
(3)
VSR LOS Sensitivity Range 5 50 5 50 5 — 50 5 50 mVp-p 223-1 pattern
HYS LOS Hysteresis 2 8 2 8 2 4.6 8 2 8 dB
NOTES:
1. Input referred noise = RMS output noise/low frequency gain.
2. Input is a 622MHz square wave.
— — — — — 35 — — — dB Input referred,
—————trin,tfin ——— VID < 100mVp-p
—————200———mVVID = 5mVp-p
— 0.5 — 0.5 — 0.1 0.5 — 0.5 µs
— 0.5 — 0.5 — 0.1 0.5 — 0.5 µs
— 0.5 — 0.5 — 0.2 0.5 — 0.5 µs
3. Input is a 200MHz square wave, tr < 300ps, 8mVp-p.
4. Input is a 200MHz square wave, tr < 300ps, 1.8Vp-p.
3
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