SY88903AL - Amplifier Microchip - Free user manual and instructions

USER MANUAL SY88903AL Microchip

The SY88903AL, burst mode, high-sensitivity limiting post amplifier is designed for use in fiber-optic receivers, specially optimized for passive optical networks (PONs). 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 SY88903AL quantizes these signals and outputs PECL level waveforms.

The SY88903AL operates from a single +3.3V power supply, over temperatures ranging from -40^ to +85^ . Signals with data rates from 622Mbps up to 1.25Gbps, and as small as 5mV_pp , can be amplified to drive devices with PECL inputs.

The SY88903AL generates a Loss-of-Signal (LOS) open-collector TTL output. A programmable Loss-of-Signal level set pin (LOS LVL ) sets the sensitivity of the input amplitude detection. LOS asserts high if the input amplitude falls below the threshold set by LOS LVL and de-asserts low otherwise. The enable bar input (/EN) de-asserts the true output signal without removing the input signal. The LOS output can be fed back to the /EN input to maintain output stability under a loss-of-signal condition. Typically, 3.4dB LOS hysteresis is provided to prevent chattering.

All support documentation can be found on Micrel's web site at: www.micrel.com.

Features

• Single 3.3V power supply
• Fast LOS release/assert (<500ns) time for PON applications
  • 622Mbps to 1.25Gbps operation
• Low-noise PECL data outputs
• High gain LOS
• Chatter-free Open-Collector TTL signal detect (LOS) output with internal 4.75kΩ pull-up resistor
• TTL /EN input
• Programmable LOS level set (LOS LVL)
  • Available in a tiny 10-pin MSOP package

Applications

• GPON/GEPON/EPON
• Gigabit Ethernet, 1062Mbps Fibre Channel
• OC-12/24 SONET/SDH
- Low-gain TIA interface
• High-gain line driver and line receiver

Markets

• FTTH/FTTP
• Datacom/telecom
  • Optical transceiver

Typical Application Circuit

From Transimpedance Amp. 0.1µF 0.1µF 50Ω 50Ω DIN /DIN GND VCC LOS /EN VCC SY88903AL DOUT /OUT VREF LOSLVL VCC 15kΩ 0.1µF 130Ω 130Ω 0.1µF To CDR

Ordering Information

Part Number	Package Type	Operating Range	Package Marking	Lead Finish
SY88903ALKG K10-1	Industrial 903A	with Pb-Free bar line indicator		NiPdAu Pb-Free
SY88903ALKGTR ^(1)	K10-1 Industrial	903A with Pb-Free bar line indicator		NiPdAu Pb-Free

Note:
1. Tape and Reel.

Pin Configuration

/EN 1 DIN 2 /DIN 3 VREF 4 LOSLVL 5 10 VCC 9 DOUT 8 /DOUT 7 LOS 6 GND 10-Pin MSOP (K10-1)

Pin Description

Pin Number	Pin Name Type	Pin Function
1	/EN	TTL Input: Default is HIGH.	/Enable: This input enables the outputs when it is LOW. Note that this input is internally connected to a 25kΩ pull-up resistor and will default to a logic HIGH state if left open.
2 DIN Data Input True data input.
3 /DIN Data Input Complementary data input.
4	VREF		Reference voltage: Placing a capacitor here to V_CC helps stabilize LOS_LVL .
5	LOSLVL	Input	Loss-of-Signal Level Set: a resistor from this pin to V_CC sets the threshold for the data input amplitude at which LOS will be asserted.
6	GND	Ground	Device ground.
7	LOS	Open-collector TTL output w/internal 4.75kΩ pull-up resistor	Loss-of-Signal: asserts high when the data input amplitude falls below the threshold set by LOS_LVL .
8	/DOUT	PECL Output	Complementary data output.
9	DOUT PECL Output True data output.
10	VCC	Power Supply	Positive power supply.

Absolute Maximum Ratings ^(1)

Supply Voltage ( V_cc ) 0V to +7.0V

Input Voltage (DIN, /DIN) 0 to V_CC

Output Current ( I_OUT )

Continuous....±50mA

Surge ±100mA

/EN Voltage ....0 to V_cc

V_REF Current -800 A to +500 A

LOS_LVL Voltage.... V_REF to V_CC

Lead Temperature (soldering, 20sec.)....260°C

Storage Temperature ( T_s ) -65^ to +150^

Operating Ratings ^(2)

Supply Voltage ( V_cc )....+3.0V to +3.6V

Ambient Temperature ( T_A ) -40^ to +85^

Junction Temperature ( T_J ) -40^ to +120^

Junction Thermal Resistance

MSOP (4) Still-air 113°C/W

DC Electrical Characteristics

V_CC = 3.0 to 3.6V; R_L = 50 to V_CC-2V; T_A = -40^ to +85^, typical values at V_CC = 3.3V, T_A = 25^.

Symbol	Parameter Condition	Min	Typ	Max	Units
I_CC	Power Supply Current	No output load				26	39	mA
LOS_LVL	LOS_LVL Voltage				V_REF		V_CC	V
V_OH	PECL Output HIGH Voltage				V_CC-1.085	V_CC-0.955	V_CC-0.880	V
V_OL	PECL Output LOW Voltage				V_CC-1.850	V_CC-1.705	V_CC-1.555	V
V_IHCMR	Common Mode Range				GND+2.0		V_CC	V
V_REF	Reference Voltage				V_CC-1.48	V_CC-1.32	V_CC-1.16	V

TTL DC Electrical Characteristics

V_CC = 3.0 to 3.6V; R_L = 50 to V_CC-2V; T_A = -40^ to +85^, typical values at V_CC = 3.3V, T_A = 25^.

Symbol	Parameter	Condition	Min	Typ	Max	Units
V_IH	/EN Input HIGH Voltage		2.0			V
V_IL	/EN Input LOW Voltage				0.8	V
I_IH	/EN Input HIGH Current	V_IN = 2.7V V_IN = V_CC			20100	μAμA
I_IL	/EN Input LOW Current	V_IN = 0.5V	-0.3			mA
V_OH	LOS Output HIGH Level	V_CC ≥ 3.3V, I_OH-MAX < 160μA V_CC < 3.3V, I_OH-MAX < 160μA	2.42.0			VV
V_OL	LOS Output LOW Level	I_OL = +2mA			0.5	V

Notes:

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 rating 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.

AC Electrical Characteristics

V_CC = 3.0 to 3.6V; R_L = 50 to V_CC-2V; T_A = -40^ to +85^, typical values at V_CC = 3.3V, T_A = 25^.

Symbol	Parameter Condition	Min Typ Max	Units
tr,tf Output	Rise/Fall Time(20% to 80%)	Note 3 260				ps
tJITTER	DeterministicRandom	Note 4Note 5		155		ps_PP ps_RMS
V_ID Differential Input Voltage Swing See Figure 1 5 1800 mV						PP
V_OD	Differential Output Voltage Swing	V_ID ≥ 18mV_PP , See Figure 1		1500		mV_PP
t_OFF	LOS Release Time	Note 8		40	500	ns
t_ON	LOS Assert Time	Note 8		125	500	ns
LOS_AL	Low LOS Assert Level	R_LOSLVL = 15k , Note 6		2.3		mV_PP
LOS_DL	Low LOS De-assert Level	R_LOSLVL = 15k , Note 6		3.4		mV_PP
HSY_L	Low LOS Hysteresis	R_LOSLVL = 15k , Note 7		3.4		dB
LOS_AM	Medium LOS Assert Level	R_LOSLVL = 5k , Note 6	2	4.2		mV_PP
LOS_DM	Medium LOS De-assert Level	R_LOSLVL = 5k , Note 6		6.2	9	mV_PP
HSY_M	Medium LOS Hysteresis	R_LOSLVL = 5k , Note 7	2	3.4	5	dB
LOS_AH	High LOS Assert Level	R_LOSLVL = 100 , Note 6	8	10.8		mV_PP
LOS_DH	High LOS De-assert Level	R_LOSLVL = 100 , Note 6		16.4	21	mV_PP
HSY_H	High LOS Hysteresis	R_LOSLVL = 100 , Note 7	2	3.4	5	dB
B_-3dB	3dB Bandwidth			1		GHz
A_V(Diff)	Differential Voltage Gain			42		dB
S_21	Single-Ended Small-Signal Gain		30	36		dB

Notes:

1. Amplifier in limiting mode. Input is a 200MHz square wave.
2. Deterministic jitter measured using 1.25Gbps K28.5 pattern, V_ID = 10 mV_PP .
3. Random jitter measured using 1.25Gbps K28.7 pattern, V_ID = 10mV_PP .
4. See "Typical Operating Characteristics" for a graph showing how to choose a particular R_LOSLVL for a particular LOS assert and its associated de-assert amplitude.
5. This specification defines electrical hysteresis as 20log (LOS De-assert/LOS Assert). The ratio between optical hysteresis and electrical hysteresis is found to vary between 1.5 and 2 depending upon the level of received optical power and ROSA characteristics. Based on that ratio, the optical hysteresis corresponding to the electrical hysteresis range 1dB-4.5 dB, shown in the AC characteristics table, will be 0.5dB-3dB Optical Hysteresis.
6. In real world applications, the LOS Release/Assert time can be strongly influenced by the RC time constant of the AC-coupling cap and the 50Ω input termination. To keep this time low, use a decoupling cap with the lowest value that is allowed by the data rate and the number of consecutive identical bits in the application (typical values are in the range of 0.001μF to 1.0μF).

Typical Operating Characteristics

V_CC = 3.3V, T_A = 25^, R_L = 50 to V_CC-2V, unless otherwise stated.

Functional Block Diagram

graph TD
    DIN --> LimitingAmplifier
    /DIN --> LimitingAmplifier
    VREF --> LimitingAmplifier
    VCC --> LimitingAmplifier
    GND --> LimitingAmplifier
    LOSLVL --> LevelDetect
    LimitingAmplifier --> PECLBuffer
    PECLBuffer --> TTLBuffer
    TTLBuffer --> LevelDetect
    LevelDetect --> OC-TTLBuffer
    OC-TTLBuffer --> LOS
    DOUT --> LimitingAmplifier
    /DOUT --> LimitingAmplifier
    /EN --> TTLBuffer
    Vcc --> OC-TTLBuffer
    4.75kΩ --> OC-TTLBuffer

Detailed Description

The SY88903AL high-sensitivity limiting post amplifier operates from a single +3.3V power supply, over temperatures from -40°C to +85°C. Signals with data rates from 622Mbps up to 1.25Gbps, and as small as 5mVpp, can be amplified. Figure 1 shows the allowed input voltage swing. The SY88903AL generates an LOS output, allowing feedback to /EN for output stability. LOS _LVL sets the sensitivity of the input amplitude detection.

Input Amplifier/Buffer

Figure 2 shows a simplified schematic of the 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 42dB differential voltage gain. Since it is a limiting amplifier, the SY88903AL outputs typically 1500mVpp voltage-limited waveforms for input signals that are greater than 12mVpp . Applications requiring the SY88903AL to operate with high-gain should have the upstream TIA placed as close as possible to the SY88903AL's input pins to ensure the best performance of the device.

Output Buffer

The SY88903AL's PECL output buffer is designed to drive 50Ω lines. The output buffer requires appropriate termination for proper operation. An external 50Ω resistor to Vcc-2V for each output pin provides this. Figure 3 shows a simplified schematic of the output stage.

Loss-of-Signal

The SY88903AL generates a chatter-free loss-of-signal (LOS) open-collector TTL output with internal 4.75kΩ pull-up resistor 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 de-asserts low otherwise. LOS can be fed back to the enable (/EN) input to maintain output stability under a loss of signal condition. /EN de-asserts low the true output signal without removing the input signals. Typically, 3.4dB LOS hysteresis is provided to prevent chattering.

Loss-of-Signal-Level Set

A programmable LOS level set pin (LOS LVL ) sets the threshold of the input amplitude detection. Connecting an external resistor between VCC and LOS LVL sets the voltage at LOS LVL . This voltage ranges from V_CC to V_REF . The external resistor creates a voltage divider between V_CC and V_REF , as shown in Figure 5.

Hysteresis

The SY88903AL provides typically 3.4dB LOS electrical hysteresis. By definition, a power ratio measured in dB is 10log (power ratio). Power is calculated as V_IN^2/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 data sheet. The SY88903AL is an electrical device, this data sheet refers to hysteresis in electrical terms. With 3.4dB LOS hysteresis, a voltage factor of 1.5 is required to assert or de-assert LOS.

Figure 1. V_IS and V_ID Definition

VREF 50Ω 50Ω 0.1μF DIN 0.1μF /DIN AC-Coupling Capacitors VCC ESD STRUCTURE GND

Figure 2. Input Structure

VCC DOUT /DOUT GND ESD STRUCTURE

Figure 3. Output Structure

VCC 4.75kΩ LOS

Figure 4. LOS Output Structure

Figure 5. LOS LVL Setting Circuit
Note: Recommended value for RLOSLVL is 15kΩ or less.

Related Product and Support Documentation

Part Number Function Data Sheet Link
Application Notes	Notes on Sensitivity and Hysteresis in Micrel Post Amplifiers	http://www.micrel.com/product-info/app_hint+notes.shtml

Package Information

NOTES: 1. DIMENSIONS ARE IN MM (INCHES). 2. CONTROLLING DIMENSION: MM 3. DIMENSION DOES NOT INCLUDE MOLD FLASH OR PROTRUSIONS, EITHER OF WHICH SHALL NOT EXCEED 0.20 (0.008) PER SIDE.

Rev. 00

10-Pin MSOP (K10-1)

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL [phone] FAX [phone] 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.

© 2005 Micrel. Incorporated.