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Micrel, Inc.
3.3V/5V 622Mbps PECL LOW-POWER LIMITING POST AMPLIFIER WITH TTL SIGNAL DETECT
DESCRIPTION
SY88793V
SY88793V
FEATURES
s s s s s s s Single 3.3V or 5V power supply Up to 622Mbps operation Low noise PECL data outputs Chatter-free TTL Signal Detect (SD) output TTL EN input Programmable SD level set (SDLVL) Available in a tiny 10-pin MSOP (3mm) package
APPLICATIONS
s 622Mbps SONET/SDH s Small form factor transceivers s High-gain line driver and line receiver
The SY88793V 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 SY88793V quantizes these signals and outputs PECL level waveforms. The SY88793V 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 622Mbps and as small as 5mVp-p can be amplified to drive devices with PECL inputs. The SY88793V generates a TTL SD output. A programmable signal-detect level set pin (SDLVL) sets the sensitivity of the input amplitude detection. SD asserts high if the input amplitude rises above the threshold set by SDLVL and deasserts low otherwise. EN deasserts the true output signal without removing the input signal. Typically 6dB SD hysteresis is provided to prevent chattering.
TYPICAL APPLICATIONS CIRCUIT
VCC
SD From Transimpedance Amp.
0.1F 0.1F
50 DIN /DIN 50
EN
DOUT
0.1F 0.1F
Rpd
SY88793V
SDLVL VREF
/DOUT Rpd
To CDR
GND
VCC 100k
0.1F
GND
For 3.3V, Rpd = 120 For 5V, Rpd = 220
M9999-072505 hbwhelp@micrel.com or (408) 955-1690
Rev.: B
Amendment: /0
1
Issue Date: July 2005
Micrel, Inc.
SY88793V
PACKAGE/ORDERING INFORMATION
EN 1 DIN 2 /DIN 3 VREF 4 SDLVL 5
10 VCC 9 DOUT 8 /DOUT 7 SD 6 GND
Ordering Information
Part Number SY88793VKC SY88793VKCTR(1) SY88793VKG Package Type K10-1 K10-1 K10-1 K10-1 Operating Range Commercial Commercial Industrial Industrial Package Marking 793V 793V 793V with Pb-Free bar-line indicator 793V with Pb-Free bar-line indicator Lead Finish Sn-Pb Sn-Pb Pb-Free NiPdAu Pb-Free NiPdAu
10-Pin MSOP (K10-1)
SY88793VKGTR(1)
Note: 1. Tape and Reel.
PIN DESCRIPTION
Pin Number 1 2 3 4 5 6 7 Pin Name EN DIN /DIN VREF SDLVL GND SD Input Ground Open-collector TTL output w/ internal 6.75k pullup resistor PECL Output PECL Output Power Supply 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. Signal-Detect Level Set: A resistor from this pin to VCC sets the threshold for the data input amplitude at which SD will be asserted. Device ground. Signal-Detect: Asserts high when the data input amplitude rises above the threshold set by SDLVL.
8 9 10
/DOUT DOUT VCC
Complementary data output. True data output. Positive power supply.
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Micrel, Inc.
SY88793V
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 SDLVL Voltage ................................................. VREF to VCC Lead Temperature (soldering, 20 sec.) ................... +260C 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 SDLVL VIH VIL IIH IIL VOH VOL VOH VOL VOFFSET VIHCMR VREF
Note 1. Note 2. Note 3.
Parameter Power Supply Current SDLVL Voltage EN Input HIGH Voltage EN Input LOW Voltage EN Input HIGH Current EN Input LOW Current SD Output HIGH Level SD Output LOW Level 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 V V
VREF 2.0
VIN = 2.7V VIN = VCC VIN = 0.5V VCC > 3.3V VCC < 3.3V IOL = +2mA 50 to VCC-2V output load 50 to VCC-2V output load Note 2 Note 3 -0.3 2.4 2.0
20 100
0.5 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 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, Inc.
SY88793V
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 SD Hysteresis SD Release Time SD Assert Time Differential Output Rise/Fall Time (20% to 80%) Differential Input Voltage Swing Differential Output Voltage Swing SD 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 0.5 400
Units dB s s ps mVPP mVPP mVPP
5 VID 18mVPP VID = 5mVPP 5 38 700 26 32 1500 400
1800
50
mVPP dB MHz dB
TYPICAL OPERATING CHARACTERISTICS
120 100 VID (mVp-p) 80 60
SD Assert and Deassert Levels vs. SDLVL
VSUP = 3.3V TA = 25C 622Mbps Pattern 223-1
140 120 100 VID (mVp-p) 80 60 40
SD Assert and Deassert Levels vs. RSDLVL
VSUP = 3.3V TA = 25C 622Mbps Pattern 223-1
ASSERT
ASSERT
40 20
DEASSERT
20 1 1.2 1.4 1 0
DEASSERT
0
10000
10
1000
SDLVL (referenced to VCC) (V)
RSDLVL ()
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100000
100
0
0.2 0.4 0.6 0.8
Micrel, Inc.
SY88793V
DETAILED DESCRIPTION
The SY88793V 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 622Mbps and as small as 5mVp-p can be amplified. Figure 1 shows the allowed input voltage swing. The SY88793V generates an SD output. SDLVL sets the sensitivity of the input amplitude detection. Input Amplifier/Buffer Figure 2 shows a simplified schematic of the SY88793V's input stage. The high-sensitivity of the input amplifier allows signals as small as 5mVPP to be detected and amplified. The input amplifier allows input signals as large as 1800mVPP. Input signals are linearly amplified with a typically 38dB differential voltage gain. Since it is a limiting amplifier, the SY88793V outputs typically 1500mVPP voltage-limited waveforms for input signals that are greater than 18mVPP. Applications requiring the SY88793V to operate with highgain should have the upstream TIA placed as close as possible to the SY88793V's input pins to ensure the best performance of the device. Output Buffer The SY88793V'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. Signal-Detect The SY88793V generates a chatter-free SD open-collector TTL output with internal 6.75k pullup resistor as shown in Figure 4. SD is used to determine that the input amplitude is large enough to be considered a valid input. SD asserts high if the input amplitude rises above the threshold set by SDLVL and deasserts low otherwise. SD 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 6dB SD hysteresis is provided to prevent chattering. Signal-Detect Level Set A programmable SD level set pin (SDLVL) sets the threshold of the input amplitude detection. Connecting an external resistor between VCC and SDLVL sets the voltage at SDLVL. This voltages ranges from VCC to VREF. The external resistor creates a voltage divider between VCC and VREF as shown in Figure 5. If desired, an appropriate external voltage may be applied rather than using a resistor. The smaller the external resistor, implying a smaller voltage difference from SDLVL to VCC, the smaller the SD sensitivity. Hence, larger input amplitude is required to assert SD. "Typical Operating Characteristics" shows the relationship between the input amplitude detection sensitivity and the SDLVL voltage. Hysteresis The SY88793V provides typically 6dB SD 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 SY88793V provides typically 3dB SD optical hysteresis. As the SY88793V is an electrical device, this datasheet refers to hysteresis in electrical terms. With 6dB SD hysteresis, a voltage factor of two is required to assert or deassert SD.
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Micrel, Inc.
SY88793V
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 RSDLVL SDLVL
VCC 6.75k SD
3k VREF
Figure 4. SD Output Structure
Figure 5. SDLVL Setting Circuit
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Micrel, Inc.
SY88793V
FUNCTIONAL BLOCK DIAGRAM
DIN /DIN VREF VCC GND
Limiting Amplifer
PECL Buffer
DOUT /DOUT
Enable
EN
Level Detect
SDLVL
SD
DESIGN PROCEDURE
Layout and PCB Design Since the SY88793V 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 SY88793V'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.
M9999-072505 hbwhelp@micrel.com or (408) 955-1690
7
Micrel, Inc.
SY88793V
10 LEAD MSOP (K10-1)
Rev. 00
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
USA
+ 1 (408) 944-0800
FAX
+ 1 (408) 474-1000
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) 2005 Micrel, Incorporated. M9999-072505 hbwhelp@micrel.com or (408) 955-1690
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