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Micrel
3.3V/5V 155Mbps PECL LOW POWER LIMITING POST AMPLIFIER W/TTL LOS
SY88803V
SY88803V
FEATURES
s s s s s s s Single 3.3V or 5V power supply Up to 155Mbps operation Low noise PECL data outputs Chatter-free TTL Loss-of-Signal (LOS) output TTL /EN input Programmable LOS level set (LOSLVL) Available in a tiny 10-pin MSOP (3mm) package
DESCRIPTION
The SY88803V low power limiting post amplifier is designed for use in fiber-optic receivers. The device connects to typical transimpedance amplifiers (TIAs). The linear signal output from TIAs can contain significant amounts of noise and may vary in amplitude over time. The SY88803V quantizes these signals and outputs PECL level waveforms. The SY88803V operates from a single +3.3V or +5V power supply, over temperatures ranging from -40C to +85C. With its wide bandwidth and high gain, signals with data rates up to 155Mbps and as small as 5mVp-p can be amplified to drive devices with PECL inputs. The SY88803V generates a TTL LOS output. A programmable loss-of-signal level set pin (LOSLVL) sets the sensitivity of the input amplitude detection. LOS asserts high if the input amplitude falls below the threshold set by LOSLVL and deasserts low otherwise. /EN deasserts the true output signal without removing the input signal. Typically 4.6dB loss-of-signal hysteresis is provided to prevent chattering.
APPLICATIONS
s 155Mbps SONET/SDH s Small form factor transceivers s High-gain line driver and line receiver
TYPICAL APPLICATIONS CIRCUIT
VCC 2k VCC
LOS From Transimpedance Amp.
0.1F 0.1F
50 DIN /DIN 50
/EN
DOUT
0.1F 0.1F
Rpd
SY88803V
LOSLVL VCC VREF
/DOUT Rpd
To CDR
GND
100 3k
GND
For 3.3V, Rpd = 120 For 5V, Rpd = 220
Rev.: A
Amendment: /0
1
Issue Date: March 2003
Micrel
SY88803V
PACKAGE/ORDERING INFORMATION
Ordering Information
/EN 1 DIN 2 /DIN 3 VREF 4 LOSLVL 5 10 VCC 9 DOUT 8 /DOUT 7 LOS 6 GND
Part Number SY88803VKC SY88803VKCTR* SY88803VKI SY88803VKITR*
*Tape and Reel
Package Type K10-1 K10-1 K10-1 K10-1
Operating Range Commercial Commercial Industrial Industrial
Package Marking 803V 803V 803V 803V
10-Pin MSOP (K10-1)
PIN DESCRIPTION
Pin Number 1 2 3 4 5 Pin Name /EN DIN /DIN VREF LOSLVL Input Type TTL Input: Default is high. Data Input Data Input Pin Function Enable: Deasserts true data output when high. True data input. Complementary data input. Reference voltage. Loss-of-Signal Level Set: A voltage between VCC and VREF on this pin sets the threshold for the data input amplitude at which LOS will be asserted. Device ground. Loss-of-Signal: Asserts high when the data input amplitude falls below the threshold set by LOSLVL. Requires external pullup resistor. Complementary data output. True data output. Positive power supply.
6 7 8 9 10
GND LOS /DOUT DOUT VCC
Ground Open-collector TTL Output PECL Output PECL Output Power Supply
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Micrel
SY88803V
Absolute Maximum Ratings(Note 1)
Supply Voltage (VCC) ....................................... 0V to +7.0V Input Voltage (DIN, /DIN) .........................................0 to VCC Output Current (IOUT) Continuous ............................................................. 50mA Surge .................................................................... 100mA /EN Voltage ............................................................ 0 to VCC VREF Current ......................................... -800A to +500A LOSLVL Voltage ......................................................0 to VCC Storage Temperature (TS) ....................... -55C to +125C
Note 1.
Operating Ratings(Note 2)
Supply Voltage (VCC) .............................. +3.0V to +3.6V or ............................................................ +4.5V to +5.5V Ambient Temperature (TA), Note 3 ............ -40C to +85C Junction Temperature (TJ), Note 3 .......... -40C to +120C Package Thermal Resistance MSOP (JA) Still-Air .................................................. 113C/W (JB) Still-Air .................................................... 74C/W
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. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings. Commercial devices are guaranteed from 0C to +85C ambient temperature.
Note 2. Note 3.
DC ELECTRICAL CHARACTERISTICS(Note 1)
VCC = 3.0V to 3.6V or 4.5V to 5.5V; RLOAD = 50 to VCC-2V; TA = -40C to +85C; typical values at VCC = 3.3V, TA = 25C Symbol ICC LOSLVL VIH VIL IIH IIL VOL IOH VOH VOL VOFFSET VIHCMR VREF
Note 1. Note 2. Note 3.
Parameter Power Supply Current LOSLVL Voltage /EN Input HIGH Voltage /EN Input LOW Voltage /EN Input HIGH Current /EN Input LOW Current LOS Output LOW Level LOS Output Leakage PECL Output HIGH Voltage PECL Output LOW Voltage Differential Output Offset Common Mode Range Reference Voltage
Specification for packaged product only.
Condition no output load
Min
Typ 25
Max 42 VCC 0.8
Units mA V V V A A mA
VREF 2.0
VIN = 2.7V VIN = VCC VIN = 0.5V IOL = +2mA VOH = 5.5V 50 to VCC-2V output load 50 to VCC-2V output load Note 2 Note 3 -0.3
20 100
0.5 250 VCC-1.085 VCC-0.955 VCC-0.880 VCC-1.830 VCC-1.705 VCC-1.555 100 GND +1.7 VCC-1.38 VCC-1.32 VCC VCC-1.26
V A V V mV V V
The VIHCMR range is referenced to the most positive side of the differential input signal. The current provided into or from VREF must be limited to 800A source and 500A sink.
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Micrel
SY88803V
AC ELECTRICAL CHARACTERISTICS(Note 1)
VCC = 3.0V to 3.6V or 4.5V to 5.5V; RLOAD = 50 to VCC-2V; TA = -40C to +85C; typical values at VCC = 3.3V, TA = 25C Symbol HYS tOFF tON tr,tf VID VOD VSR AV(Diff) B-3dB S21
Note 1.
Parameter LOS Hysteresis LOS Release Time LOS Assert Time Differential Output Rise/Fall Time (20% to 80%) Differential Input Voltage Swing Differential Output Voltage Swing LOS Sensitivity Range Differential Voltage Gain 3dB Bandwidth Single-Ended Small-Signal Gain
Specification for packaged product only.
Condition electrical signal
Min 2
Typ 4.6 0.1 0.2
Max 8 0.5 0.5 1000
Units dB s s ps mVp-p mVp-p mVp-p
5 VID 18mVp-p VID = 5mVp-p 5 38 200 26 32 1500 400
1800
50
mVp-p dB MHz dB
TYPICAL OPERATING CHARACTERISTICS
100 90 80 70 60 50 40 30 20 10 0
3.3V LOS Assert and Deassert Levels vs. LOSLVL
3.3V TA = 25C 155Mbps Pattern 223-1
0
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL (referenced to VCC) (V)
100 90 80 70 60 50 40 30 20 10 0
5V LOS Assert and Deassert Levels vs. LOSLVL
5.0V TA = 25C 155Mbps 23 Pattern 2 -1
VID (mVp-p)
VID (mVp-p)
0
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL (referenced to VCC) (V)
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Micrel
SY88803V
DETAILED DESCRIPTION
The SY88803V low-power limiting post-amplifier operates from a single +3.3V or +5V power supply, over temperatures from -40C to +85C. Signals with data rates up to 155Mbps and as small as 5mVp-p can be amplified. Figure 1 shows the allowed input voltage swing. The SY88803V generates an LOS output. LOSLVL sets the sensitivity of the input amplitude detection. Input Amplifier/Buffer Figure 2 shows a simplified schematic of the SY88803V's input stage. The high-sensitivity of the input amplifier allows signals as small as 5mVp-p to be detected and amplified. The input amplifier allows input signals as large as 1800mVp-p. Input signals are linearly amplified with a typically 38dB differential voltage gain. Since it is a limiting amplifier, the SY88803V outputs typically 1500mVp-p voltage-limited waveforms for input signals that are greater than 18mVp-p. 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 The SY88803V's PECL output buffer is designed to drive 50 lines. The output buffer requires appropriate termination for proper operation. An external 50 resistor to VCC-2V 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 The SY88803V generates a chatter-free TTL LOS. A recommended 2k pullup resistor to VCC is required for 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 LOSLVL and 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. Loss-of-Signal Level Set A programmable loss-of-signal level set pin (LOSLVL) sets the threshold of the input amplitude detection. Setting a voltage on LOSLVL between V CC and VREF sets this threshold. If desired, a resistor divider between VCC and VREF, as shown in Figure 5, also creates this threshold. The smaller the voltage difference from LOSLVL to VCC, the 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 LOSLVL voltage. Hysteresis The SY88803V provides typically 4.6dB LOS electrical hysteresis. By definition, a power ratio measured in dB is 10log(power ratio). Power is calculated as V2IN/R for an 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.
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Micrel
SY88803V
DATA+
2.5mV (Min.) VIS(mVp-p) 900mV (Max.)
DATA--
(DATA+) -- (DATA--)
5mVp-p (Min.) VID(mVp-p) 1800mVp-p (Max.)
Figure 1. VIS and VID Definitions
VCC
VCC
ESD STRUCTURE
DOUT /DOUT
DIN
/DIN
ESD STRUCTURE
GND
GND
Figure 2. Input Structure
Figure 3. Output Structure
VCC R1 LOSLVL
VCC LOS 2k
R2 VREF
Figure 4. LOS Output Structure
Figure 5. LOSLVL Setting Circuit
Notes. LOS LVL = VCC - 1.32V +
R1 + R2 2.6k
R2 x 1.32V R1 + R2
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Micrel
SY88803V
FUNCTIONAL BLOCK DIAGRAM
DIN /DIN VREF VCC GND
Limiting Amplifer
PECL Buffer
DOUT /DOUT
Enable
/EN
Level Detect
LOSLVL
LOS
DESIGN PROCEDURE
Layout and PCB Design Since the SY88803V is a high-frequency component, performance can be largely determined by the board layout and design. A common problem with high-gain amplifiers is the feedback from the large swing outputs to the input via the power supply. The SY88803V's ground pin should be connected to the circuit board ground. Use multiple PCB vias close to the part to connect to ground. Avoid long, inductive runs which can degrade performance.
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Micrel
SY88803V
10 LEAD MSOP (K10-1)
Rev. 00
MICREL, INC.
TEL
1849 FORTUNE DRIVE SAN JOSE, CA 95131
FAX
USA
+ 1 (408) 944-0800
+ 1 (408) 944-0970
WEB
http://www.micrel.com
The information furnished by Micrel in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2003 Micrel, Incorporated.
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