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SY88212L
3.3V, 2.5Gbps Laser Diode Driver with Integrated Bias and APC
General Description
The SY88212L is a single supply 3.3V laser driver for datacom and telecom applications with data rates from 155Mbps up to 2.5Gbps. The driver can deliver modulation current up to 85mA, and provides a high compliance voltage that makes it suitable for high-current operation with the laser DC-coupled to it. The drivers have integrated bias and Automatic Power Control (APC) functions. All support documentation can be found on Micrel's web site at: www.micrel.com.
Features
* * * * * * 2.4V minimum laser compliance voltage Operation up to 2.5Gbps Modulation current up to 85mA Bias current up to 70mA Power monitoring Available in 24-pin (4mm x 4mm) MLF(R) package
Applications
* Multi-rate LAN, MAN applications up to 2.5Gbps: FC, GbE, SONET OC3/12/24 and SDH STM1/4/8 * SFF, SFP modules
Markets
* Telecom, Datacom ___________________________________________________________________________________________________________
Typical Application
MLF and MicroLeadFrame are registered trademarks of Amkor Technology. Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com
April 2008
M9999-040908-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SY88212L
Ordering Information(1)
Part Number SY88212LMG SY88212MGTR(2)
Notes: 1. Contact factory for die availability. Dice are guaranteed at TA = +25C, DC Electrical only. 2. Tape and Reel.
Package Type MLF-24 MLF-24
Operating Range Industrial Industrial
Package Marking 212L with Pb-Free bar-line indicator 212L with Pb-Free bar-line indicator
Lead Finish NiPdAu Pb-Free NiPdAu Pb-Free
Pin Configuration
24-Pin MLF(R) (MLF-24)
April 2008
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Micrel, Inc.
SY88212L
Pin Description
Pin Number 2 3 5 Pin Name DIN+ DIN/TXDISABLE Pin Function Non-inverting input data. Internally terminated with 50 to a reference voltage. Inverting input data. Internally terminated with 50 to a reference voltage. Transmitter Complementary TXDISABLE. TTL Input. The transmitter is enabled when this pin is asserted High and disabled when this pin is asserted Low. A 6.3k resistor must be installed between pins 6 and GND if /TXDISABLE is used as TTL input Transmitter Disable. TTL input. The transmitter is enabled when this pin is asserted Low and disabled when this pin is asserted High or left open. A 6.3k resistor must be installed between pin 5 and GND if TXDISABLE is used as TTL input. Active low TTL/CMOS. Internally pulled-up. Pull-down with a 22k or lower resistance or apply a low level signal (<0.8 V) to enable bias and modulation. Keep floating or apply a high level (>2 V) to disable. Internal oscillator setting option. Install a 0 resistor from this pin to VCC or leave it open to set the frequency. Refer to the frequency table. Transmitter Fault Indicator. Open collector. Active High. Power Monitor. Provides a current which is proportional to the sum of bias current and half of modulation current. Install a resistor between this pin and GND to convert that current to a voltage. Inverting laser bias current output. Pull-up to VCC with a resistor. Non-inverting laser bias current output, sources current when TXDISABLE is inserted Low (see pin 6 description) or /TXDISABLE is inserted High (see pin 5 description). Connect to the cathode of the laser through a resistor. Non-inverted modulation current output. Provides modulation current when input data is positive. Inverted modulation current output. Provides modulation current when input data is negative. Input from the laser monitoring photodiode. Connect to the anode of the photodiode for APC operation. Install a resistor between this pin and GND to set the maximum bias current for the closed loop operation. The APC loop controls the bias current up to the level of BIASMAX. When the bias current reaches the maximum value set through this pin, the driver continues to sink a current equal to this maximum. For open loop operations, this pin sets the bias current. Modulation current setting and control. The modulation current is set by installing an external resistor from this pin to ground or using a current source. Bias current setting and control. The bias current is set by installing an external resistor from this pin to ground or using a current source. Connect a 50K resistor to GND for open loop operation. Ground. Ground and exposed pad must be connected to the plane of the most negative potential. Supply Voltage. Bypass with a 0.1F//0.01F low ESR capacitor as close to VCC pin as possible.
6
TXDISABLE
7
/EN
9 10 12
OSC TXFAULT PWRMON
13 14
BIASBIAS+
16 17 20 22
MOD+ MODMD BIASMAX
23 24 8, 11,19 1, 4, 15, 18, 21
MODSET APCSET GND VCC
Truth Table
DIN+ L H X DINH L X /EN L L H MOD+ H L H
(1)
Oscillator Frequency
MODL H L Laser Output(2) L H L OSC Open VCC Frequency (MHz) 25 50
Notes: 1. IMOD = 0 when MOD+ = H. 2. Assuming that the cathode of the laser is tied to MOD+.
April 2008
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Micrel, Inc.
SY88212L
Absolute Maximum Ratings(1)
Supply Voltage (VCC).................................... -0.5V to +4.0V CML Input Voltage (VIN) ....................VCC-1.2V to VCC+0.5V TTL Control Input Voltage (VI).....................0V to VCC +0.3V Lead Temperature (soldering, 20sec.)..................... +260C Storage Temperature (Ts) .........................-65C to +150C
Operating Ratings(2)
Supply Voltage (VCC).................................... +3.0V to +3.6V Ambient Temperature (TA) .......................... -40C to +85C Package Thermal Resistance(3) MLF(R) (JA) Still-air........................................................50C/W (JB) ...................................................................30C/W
DC Electrical Characteristics
TA = -40C to +85C and VCC = +3.0V to +3.6V. Unless otherwise noted, typical values are VCC = +3.3V, TA = 25C, IMOD = 25mA, IBIAS = 20mA.
Symbol ICC VMOD_MIN Parameter Power Supply Current Minimum Voltage Required at the Driver Output, MOD+ and MOD-, for Proper Operation Minimum Voltage Required at the Driver Output, BIAS+ and BIAS-, for Proper Operation Bias-ON Current Bias-OFF Current Input Resistance at DIN+ and DINDifferential Input Voltage Swing APCFAULT Output Low APCFAULT Output Leakage High Voltage /EN, Low Voltage /EN, TXDISABLE, /TXDISABLE TXDISABLE, /TXDISABLE 1.25 50 1500 IOL = 2mA VOH = VCC 2 0.8 Voltage at Bias pin 0.8V Current at BIAS pin when /EN is high or TXDISABLE is High Single ended 42.5 100 50 Condition Modulation and Bias currents excluded 0.6 Min Typ 55 Max 95
(4)
Units mA V
VBIAS_MIN
0.8
V
IBIAS IBIAS_OFF RIN VDIFF-IN (DIN) VOL IOH VIH VIL VPWRMON IMD
Notes:
1
70 150 57.5 2400 0.5 100
mA A mVPP V A V V V A
Maximum voltage at PWRMON pin Current range at MD pin
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 ratings conditions for extended periods may affect device reliability. 2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings. 3. Package Thermal Resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB. JB uses a 4-layer and JA in still air unless otherwise stated. 4. ICC = 95mA for worst-case conditions with IMOD = 85mA, IBias = 70mA, TA = +85C, VCC = 3.6V.
April 2008
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Micrel, Inc.
SY88212L
AC Electrical Characteristics
TA = -40C to +85C and VCC = +3.0V to +3.6V. Unless otherwise noted, typical values are VCC = +3.3V, TA = 25C, IMOD = 25mA, IBIAS = 20mA.
Symbol Parameter Data Rate IMOD Modulation Current(5) Condition NRZ AC-coupled DC-coupled, voltage at MOD pin 0.6V Current at MOD+ when /EN is high or TXDISABLE is Low Current at MOD- when /EN is high or TXDISABLE is High 20% to 80%, IMOD = 60mA 20% to 80%, IMOD = 60mA 155Mbps data rate Jitter Total Jitter(7) 622Mbps data rate 1.25Gbps data rate 2.5Gbps data rate Power up with /EN Low tINIT
Notes: 5. Load = 15. 6. Assuming VCC = 3.0V, Laser bandgap voltage = 1V, laser package inductance = 1nH, laser equivalent series resistor = 5, and damping resistor = 10. 7. Total jitter is measured using 2 - 1 PRBS pattern.
7
Min 0.155 10 10
Typ
Max 2.5 85 70(6) 150 150
Units Gbps mA mA A A ps ps
IMOD_OFF
Modulation OFF Current
tr tf
Output Current Rise Time Output Current Fall Time
60 60
85 85 30 30 30 30 12 10
psPP
s s
APC Loop Initialization Time
/EN changes from high to low with power ON.
March 2008
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Micrel, Inc.
SY88212L
Functional Diagram
March 2008
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SY88212L APC Loop Function At start up, with the driver enabled, the laser turns ON within a few microseconds and its back facet monitoring photodiode starts to generate a photocurrent proportional to the optical power. The photocurrent is fed back to the MD pin on the driver where it's converted to a voltage. The conversion voltage is compared to APCSET on the driver. At equilibrium, the feedback voltage equals the APCSET voltage and the laser optical power reaches its nominal value. If the laser power deviates from its nominal value, the APC loop brings it back to its nominal setting. APC Loop Failure TXFAULT is asserted High if the bias current reaches BIASMAX or if the APC loop counter reaches its minimum or its maximum counts. Interfacing the Driver with the Laser Diode As shown in the "Typical Application" drawing, MOD+ pin is connected to the laser cathode through a 10 resistor and MOD- pin is connected to VCC with a 15 resistor equivalent to 10 (damping resistor) in series with the laser (equivalent resistor of 5). The laser can be driven differentially by connecting MOD- to the anode of the laser through 15 (15 pull-up removed) and isolating the anode of the laser from VCC with an inductor. For better results at 2.5Gbps, the driver can be ACcoupled to the laser as shown in Figure 1.
Detailed Functional Description
The SY88212L laser driver is comprised from a fast modulator, a fast bias circuit, and a digital APC loop that allows for fast laser turn-ON time. The driver features a power monitoring function. BIAS and Modulation Setting Bias and modulation currents are set by installing resistors from APCSET (pin 24) to ground and from MODSET (pin 23) to ground respectively or by applying a negative current at those pins. IMD variation versus RAPCSET resistor, IBIAS variation versus RBIASMAX resistor, and IMOD variation versus RMODSET resistor are shown on page 8. BIASMAX A resistor between BIASMAX pin and ground sets the maximum bias the driver can sink. At normal operation, the bias current tracks the laser optical power through the laser monitoring photodiode and the APC loop to compensate for any power deviation from the nominal value set at the start of operation using APCSET. If for any failure (laser or photodiode degradation, open feedback circuit etc...) the APC loop keeps increasing the bias current trying to compensate for the low power indication, the bias current will stop increasing when it reaches BIASMAX value and continues to operate at that maximum value and TXFAULT asserted high. BIASMAX also controls the bias current when the circuit is operating in the open loop mode.
Figure 1. Laser AC-Coupled to the Driver Typical Application
March 2008
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M9999-030708-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SY88212L
Typical Characteristics
Functional Characteristics
March 2008
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Micrel, Inc.
SY88212L
Input and Output Stages
Figure 2a. Simplified Input Stage
Figure 2b. Simplified Output Stage
Interfacing DIN Input to Different Logic Drivers
Figure 3a. Driving DIN with PECL Outputs
Figure 3b. Driving DIN with CML Outputs
March 2008
9
M9999-030708-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SY88212L
Package Information
24-Pin (3mm x 3mm) MicroLeadFrame(R) (MLF-24)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet 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 a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2008 Micrel, Incorporated.
March 2008
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