SY88216L
3.3V, 2.5Gbps Burst Mode Laser Driver
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.c om
July 2008
M9999-071108-C
hbwhelp@micrel.com or (408) 955-1690
General Description
The SY88216L is a single supply 3.3V burst mode laser
driver for A-PON, B-PON, EPON, GE-PON, and G-PON
applications with data rates from 155Mbps up to 2.5Gbps.
The driver c an deliver modulat ion current u p to 85m A, and
provides a high compliance voltage that makes it suitable
for high-cur rent operation with the laser DC-coupled to it.
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
• Fast burst mode enable/disable delay
• Modulation current up to 85mA
• Bias current up to 70mA
• Infinite bias current hold time between bursts
• Safety features
• Power monitoring
• Available in 24-pin (4mm x 4mm) QFN package
Applications
• Multi-rate burst mode applications: A-PON, B-PON,
G-PON, E-PON, GE-PON
Markets
• Fiber-to-the-Premises (FTTP): Fiber-to-the-Home
(FTTH), Fiber-to-the-Business (FTTB)
• FTTC (Fiber-to-the-Curb)
___________________________________________________________________________________________________________
Typical Appli cation
Micrel, Inc.
SY88216L
July 2008 2 M9999-071108-C
hbwhelp@micrel.com or (408) 955-1690
Ordering Information(1)
Part Number Package
Type Operating
Range Package Marking Lead Finish
SY88216LMG QFN-24 Industrial 216L with Pb-Free bar-l ine ind icator NiPdAu Pb-Free
SY88216LMGTR(2) QFN-24 Industrial 216L with Pb-Free bar -l ine ind i cator NiPdAu Pb-Free
Notes:
1. Contact f act ory for die availabi lit y. Dice are guaranteed at TA = +25°C, DC Electrical only.
2. Tape and Reel.
Pin Configuration
24-Pin QFN
Micrel, Inc.
SY88216L
July 2008 3 M9999-071108-C
hbwhelp@micrel.com or (408) 955-1690
Pin Description
Pin Number Pin Name Pin Function
2 DIN+ Non-inverting input data. Internally terminated with 50Ω to a referen ce vol tage.
3 DIN- Inverting input data. Internally terminated with 50Ω to a reference voltage.
5 BEN+ Non-inverting burst enable. Accepts any input, single-ended or differential: TTL/CMOS,
LVPECL, CML, LVDS, HSTL, and SSTL. BEN requires an external termination. See Figure 2.
6 BEN- Inverting burst enable. Accepts any input, single-ended or differential: TTL/CMOS, LVPECL,
CML, LVDS, HSTL, and SSTL. BEN requires an external termination. See Figure 2.
7 /EN Active low TTL/CMOS. Internally pulled-up. Pull-down with a 22kΩ 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.
9 OSC Internal oscillator setting optio n. Instal l a 0Ω resistor from this pin to VCC or leave it open to
set the frequency. Refer to the frequency table.
10 /APCFAULT Indicates APC failure when low. Active low TTL/CMOS.
12 PWRMON 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.
13 BIAS- Inverting laser bias current output. Pull-up to VCC with a resistor.
14 BIAS+ Non-inverti ng las er bias current output, sources current when BEN is high. Connect to the
cathode of the laser throu gh a r esistor .
16 MOD+ Non-inverted modulation current output. Provides modulation current when input data is
positive.
17 MOD- Inverted modulation current output. Provides modulation current when input data is negative.
20 MD Input from the laser monitoring photodiode. Connect to the anode of the photodiode for APC
operation.
22 BIASMAX 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.
23 MODSET 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.
24 APCSET 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.
8, 11,19 GND Ground. Ground and ex posed pad must be conne cted to t he plan e of the most negativ e
potential.
1, 4, 15, 18, 21 VCC Supply Voltage. Bypass with a 0.1µF//0.01µF low ESR capacitor as close to VCC pin as
possible.
Truth Table
DIN+ DIN- /EN MOD+(1) MOD- Laser
Output(2)
L H L H L L
H L L L H H
X X H H L L
Oscillator Frequency
OSC Frequency (MHz)
Open 25
VCC 50
Notes:
1. IMOD = 0 when MOD+ = H.
2. Assuming that the laser is tied to MOD+.
Micrel, Inc.
SY88216L
July 2008 4 M9999-071108-C
hbwhelp@micrel.com or (408) 955-1690
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.) ..................... +260°C
Storage Temperature (Ts) ......................... –65°C to +150°C
Operating Ratings(2)
Supply Voltage (VCC) .................................... +3.0V to +3.6V
Ambient Temperature (TA) .......................... –40°C to +85°C
Package Thermal Resistance(3)
QFN
(θJA) Still-air ........................................................ 75°C/W
(ψJB) ................................................................... 30°C/W
DC Electrical Characteristic s
TA = –40°C to +85°C and VCC = +3.0V to +3.6V. Unless otherwise noted, typical values are VCC = +3.3V,
TA = 25°C, IMOD = 25mA, IBIAS = 20m A.
Symbol Parameter Condition Min Typ Max Units
ICC Power Supply Current Modulation and Bias currents
excluded 55 95(4) mA
VMOD_MIN Minimum Voltage Required at the
Driver Output, MOD+ and MOD-,
for Proper Operation
0.6 V
VBIAS_MIN Minimum Voltage Required at the
Driver Output, BIAS+ and BIAS-,
for Proper Operation
0.8 V
IBIAS Bias-ON Current Voltage at Bias pin ≥ 0.8V 1 70 mA
IBIAS_OFF Bias-OFF Current Current at BIAS pin when /EN is
high or BEN is low 150 µA
RIN Input Resistance at DIN+ and DIN- Single ended 42.5 50 57.5 Ω
VDIFF-IN
(DIN) Differential Input Voltage Swing 100 2400 mVPP
VIL (/EN) /EN Input Low 0.8 V
VIH (/EN) /EN Input High 2 V
VOL /APCFAULT Output Low IOL = 2mA 0.5 V
IOH /APCFAULT Output Leakage VOH = VCC 100 µA
BEN+,
BEN- Burst Mode Enable Signal Single Ended 0.8 V
VIH (BEN) High Voltage BEN+, BEN- VCC + 0.3 V
VIL (BEN) Low Voltage BEN+, BEN- -0.3 V
VIN (BEN) Input Voltage Swing BEN+, BEN- 100 mV
VDIFF-IN
(BEN) Differential Input Voltage Swing BEN+, BEN- 200 mVPP
VPWRMON Maximum Voltage at PWRMON Pin 1.25 V
IMD Current Range at MD Pin 50 1500 µA
Notes:
1. Permanent device dam age may occur if absolute maximum ratings are exceeded. This is a stress rating only and functi onal operati on is not impli ed
at conditions other than thos e detailed in the operati onal sections of this data sheet. E xposure to absolute maximum ratings c onditi ons for extended
periods may affect device reliabil ity.
2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
3. Package Therm al Resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB. ψJB uses a
4-layer and θJA in still air unless otherwise stated.
4. ICC = 95mA for worst-case conditions with IMOD = 85mA, IBIAS = 70mA , TA = +85°C, VCC = 3. 6.
Micrel, Inc.
SY88216L
July 2008 5 M9999-071108-C
hbwhelp@micrel.com or (408) 955-1690
AC Electrical Characteristic s
TA = –40°C to +85°C and VCC = +3.0V to +3.6V. Unless otherwise noted, typical values are VCC = +3.3V,
TA = 25°C, IMOD = 25mA, IBIAS = 20m A.
Symbol Parameter Condition Min Typ Max Units
Data Rate NRZ 0.155 2.5 Gbps
IMOD Modulation Current(5) AC-coupled 10 85 mA
DC-coupled, Voltage at MOD Pin
≥0.6V 10 70(6) mA
IMOD_OFF Modulation OFF Current
Current at MOD+ when /EN is
High or BEN is High 150 µA
Current at MOD- when /EN is
High or BEN is Low 150 µA
tr Output Current Rise Time 20% to 80%, IMOD = 60mA 60 85 ps
tf Output Current Fall Time 20% to 80%, IMOD = 60mA 60 85 ps
Jitter Total Jitter(7)
155Mbps 30
psPP
622Mbps 30
1.25Gbps 30
2.5Gbps 30
tINIT APC Loop Initialization Time
Power up with /En Low and BEN
High 12 µs
/EN Changes from High to Low
with Power ON and BEN High 10 µs
BEN Changes from Low to High
with Power ON and /EN Low 2.5 ns
Burst Enable Delay(8, 9) 2.5 ns
Burst Disable Delay
(8, 10)
2 ns
Burst ON-Time
155Mbps 1.9 µs
622Mbps 720 ns
1.25Gbps 576 ns
2.5Gbps 576 ns
Burst OFF-Time
155Mbps 1.9 µs
622Mbps 720 ns
1.25Gbps 576 ns
2.5Gbps 576 ns
Notes:
5. Load = 15Ω.
6. A ssuming VCC = 3.0V, Laser bandgap voltage = 1V, laser package inductance = 1nH, laser equivalent series resistor = 5 Ω, and damping
resistor = 10Ω.
7. Total jitter is measured using 2 7 – 1 PRBS pattern.
8. Measured with a laser equi valent resisti ve l oad.
9. Burst E nabl e Delay is measured as the time between the instant when the BEN+ signal going from low to high reaches 50% of its amplitude
and the instant at which the modulation current or the bias current (whichever takes longer) reac hes 90% of its final value.
10. Burst Disable Del ay is measured as the time between the instant when the BEN+ signal going from high to low reaches 50% of its amp litude
and the instant at which the modulation current or the bias current (whichever takes longer) goes below 10% of its final val ue.
Micrel, Inc.
SY88216L
July 2008 7 M9999-071108-C
hbwhelp@micrel.com or (408) 955-1690
Detailed Functional Description
The SY88216L burst mode 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
modulator is comparable to a fast continuous mode
modulator that turns ON in the nanosecond range. The
bias circuit has a differential pair at the output to allow
for fast turn-ON time. Both modulator and bias
differential pairs can be enabled for burst operation by
applying a high level signal at BEN+ pin and a low level
signal at BEN- pin.
The driver features a power monitoring function.
BIAS and Modulation Setting
Bias and modulation currents are set by installing
resistors from APCSET (pin24)-to-ground and from
MODSET (pin23)-to-ground respectively or by applying a
negative current at those pins. IBIAS variation versus
RAPCSET resistor, IBIAS variation versus RBIASMAX resistor,
and IMOD variation versus RMODSET resistor are shown on
Page 8.
BIASMAX
A resistor between the BIASMAX pin and ground sets
the maximum bias the driver can sink. At normal
operatio n, the bias current tracks the laser opt ical 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 any failure occurs (laser or photodiode
degradation, open feedback circuit etc.) the APC loop
keeps increasing the bias current in an effort to
compensate for the low power indication, the bias
current will then stop increasing when it reaches
BIASMAX value and continue to operate at that
maximum value and APCFAULT asserted.
BIASMAX also controls the bias current when the circuit
is operating in the open loop mode.
APC Loop Function
At start up, with the driver enabled and burst mode
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 a nd the laser optica l power reaches its
nominal value. If the laser power deviates from its
nominal value, t he APC loop br ings it back to its n om inal
setting. After everything is settled to its nominal value
and the BEN changes from high to low to disable the
burst mode, the instantaneous bias current value is
latched until BEN switches from low to high again. Then
the bias and modulation output stages turn ON and the
bias stays equal to the stored value until the feedback
from the monitoring photodiode reaches the APCSET
value and the APC closed loop starts to regulate the
laser power.
APC Loop Failure
The APCFAULT is asserted Low if the bias current
reaches BI AS MAX or if the APC loo p c oun ter reac hes its
minimum or its maximum counts.
Interfacing the Driver with the L aser Diode
As shown on the “Typical Application” drawing, MOD+
pin is connected to the laser cathode through a 10Ω
resistor and MOD- pin is connected to VCC with a 15Ω
resistor equivalent to 10Ω (damping resistor) in series
with the laser (equivalent resistor of 5Ω). The laser can
be driven dif ferentia lly by connect ing MOD- to the anode
of the laser through 15Ω (15Ω pull-up removed) and
isolating the anode of the laser from VCC with an
inductor.
To meet the stringent laser turn-ON time, per
BPON/G PON/EPON spec , the bias (BIA S+ pi n) must be
connected to the cathode of the laser through a resistor
not an inductor as in continuous mode. BIAS- pin is
pulled-up to VCC.
Micrel, Inc.
SY88216L
July 2008 10 M9999-071108-C
hbwhelp@micrel.com or (408) 955-1690
Input and Output Stages
Figure 1a. Simplified Input Stage
Figure 1b. Simplified BEN Input Stage
Figure 1c. Simplified Output Stage
Interfacing DIN and BEN Inputs to Different Logic Drivers
Figure 2a. Dri vin g DIN and BEN with PECL Outputs
Figure 2b. Driving DIN and BEN with CML Outputs
Figure 2c. Driving BEN with LVTTL/LCMOS Outputs
Figure 2d. Driving BEN with LVDS Outputs
Micrel, Inc.
SY88216L
July 2008 11 M9999-071108-C
hbwhelp@micrel.com or (408) 955-1690
Package Information
24-Pin (3mm x 3mm) QFN
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-10 00 WEB http://w ww .micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and rel i able. However, no respons i bility is assumed by Micrel for its
use. Micrel reserves the right to change circuit ry and specific ations at any time without noti ficat ion to the customer.
Micrel Products are not designed or authorized for use as components in life support applianc es, devic es or syst ems where malf unct i on of a product
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Purchaser’s use or sale of Mi
crel Products for use in life support appliances, devices or syst ems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel f or any damages resulting from such use or sale.
© 2007 Micrel, Incorporated.
