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July 2000
ML4664*/ML4669* 10BASE-FL to 10BASE-T Converter
GENERAL DESCRIPTION
The fully pin-compatible ML4664/ML4669 pair provide conversion from 10BASE-T copper media to 10BASE-FL fiber media in a single chip. They are compliant with Ethernet IEEE 802.3 10BASE-T and 10BASE-FL standards. The ML4664/69 uses a single 5V supply, and requires no crystal or clock. Their 10BASE-FL transmitter offers a current drive output that directly drives a fiber optic LED transmitter. Their receiver offers a highly stable fiber optic data quantizer capable of accepting input signals as low as 2mVP-P with a 55dB dynamic range. The 10BASE-T portion of the pair contains current driven transmitter outputs that offer superior performance because their switching is highly symmetric, resulting in lowered RFI noise and jitter. By changing one external resistor the pair easily interfaces to 100W unshielded twisted pair, 150W shielded twisted pair, or a range of other characteristic impedances. The ML4664 does not pass along disconnect information, while the ML4669 does. A loss of light at the optical inputs does not stop link pulses from being sent at the twisted pair transmitter in the ML4664, but in the ML4669 the link pulses stop. Also, a loss of link at the twisted pair inputs will not stop the optical transmitter from sending idle in the ML4664, but the ML4669 stops sending idle.
FEATURES
s s s
Full duplex operation Five network status LED outputs Industrial temperature option
10BASE-FL FEATURES:
s
Highly stable data quantizer with 55dB input dynamic range Input sensitivity as low as 2mVP-P Up to 100mA maximum current driven fiber optic LED output for accurate launch power (PLCC package)
s s
10BASE-T FEATURES:
s s s s s
Current driven output for low RFI noise and low jitter Drives 100W unshielded or 150W shielded twisted pair Polarity detect status pin capable of driving an LED Automatic polarity correction On-chip link test with enable/disable option
* Some Packages Are Obsolete
BLOCK DIAGRAM
LTF LINK PULSE CHECK TPLED POLDIS IDLE GENERATOR RRSET RTSETOP
TPIN
2
RX SQUELCH TP
OP TX
OPOUT OPVCC
POLARITY CORRECT
LINK PULSE GENERATOR RX SQUELCH TP TPOUT 2 RTSETTP TP TX TxCAP0 TxCAP1 LMON
(LOW LIGHT)
THRESHOLD GENERATOR
QUANTIZER OPLED VDC CTIMER
2
OPIN
1
ML4664/ML4669
PIN CONFIGURATION
ML4664/ML4669 28-Pin PLCC (Q28)
CTIMER OPLED AVCC OPINP TPLED
3
TPINP
4 TPINN VCC TxCAP0 TxCAP1 GND TPOUTN TPOUTP 5 6 7 8 9 10 11
LTF
2
1 28 27 26 25 24 23 22 21 20 19 OPINN AGND VTHADJ VREF VDC GND OPOUT
12 13 14 15 16 17 18
VCC RRSET
POLDIS
LMON
TOP VIEW
ML4664/ML4669 32-Pin TQFP (H32-7)
CTIMER OPLED OPINP TPLED TPINP AVCC LTF NC
TPINN NC VCC TxCAP0 TxCAP1 GND TPOUTN TPOUTP
32 31 30 29 28 27 26 25 24 1 2 3 4 5 6 7 8 9 23 22 21 20 19 18 17 10 11 12 13 14 15 16
RTSETOP
OPVCC
RTSETP
OPINN AGND VTHADJ VREF VDC NC GND OPOUT
NC
POLDIS
RTSETP
VCC
RRSET
RTSETOP
LMON
TOP VIEW
2
OPVCC
ML4664/ML4669
PIN DESCRIPTION (Pin Number in Parentheses is for TQFP Version)
PIN NAME FUNCTION PIN NAME FUNCTION
1(29)
CTIMER
A capacitor from this pin to VCC determines the Link Monitor response time. Link Test Fail. Active high. Normally this pin is low, indicating that the link is operational. If the link goes down resulting from the absence of link pulses or frames being received, the chip will go into the Link Test Fail state and bring LTF high. When the ML4664 is in the link test fail state, the optical and twisted pair transmitters are disabled from sending data. However, the optical transmitter does send an idle signal, and link pulses are sent at the twisted pair transmitter. When the ML4669 is in link test fail state, the optical and twisted pair transmitters are disabled from sending data. Also, the optical transmitter will not send an idle signal. However, link pulses may be sent at the twisted pair transmitter, depending on the optical inputs. See Table 1. This pin may be grounded to disable Link Test. In this mode no link pulses are sent and the link will not fail if no link pulses are received. If this pin is not used as an LED driver, and is not grounded, a 2kW 5% resistor should be connected between this pin and VCC.
7(4) 8(5)
TxCAP0 TxCAP1
2(30)
LTF
An external capacitor of 680pF is tied between these two pins to set the pulse width for the preequalization on the twisted pair transmitter. If these two pins are shorted together, no pre- equalization occurs. If the ML4664/ML4669 is driving only a short cable, or board traces, these pins may be shorted. Ground reference
9(6) GND 20(18) 10(7) 11(8)
TPOUTN Pre-equalized differential balanced TPOUTP current driven output. These outputs are connected to a balanced transmit output filter which drives the twisted pair cable through pulse transformers. The output current is set with an external resistor connected to RTSET allowing the chip to drive 100W unshielded , 150W shielded twisted pair cables or a range of other characteristic impedances. Receive Polarity status. Active low LED Driver, open collector output. Indicates the polarity of the receive twisted pair regardless of auto polarity correction. When low, receive polarity is reversed. When high, receive polarity is correct. This pin may be grounded to disable the polarity circuit. If this pin is not used as an LED driver, and is not grounded, a 2kW, 5% resistor should be connected between this pin and VCC.
12(10) POLDIS
3(31)
TPLED
Indicates that reception is taking place on the TPINP, TPINN pair. Active low LED driver, open collector. It is extended 16ms for visibility. Optionally, this pin may be grounded to disable the optical output. If this pin is not used as an LED driver and is not grounded, a 2kW, 5% resistor should be connected between TPLED and VCC. Twisted Pair receive data input. When this signal exceeds the receive squelch requirements the receive data is buffered and sent to the Rx outputs. 5V input
13(11) RTSETTP When using 100W unshielded twisted pair, a 220W resistor is tied between this pin and VCC. When using 150W shielded twisted pair, a 330W resistor is tied between this pin and VCC. 15(13) RRSET A 1% 61.9kW resistor tied from this pin to VCC is used for internal biasing.
4(32) 5(1)
TPINP TPINN
16(14) RTSETOP Sets the current driven output of the transmitter. A 115W resistor should be tied between this pin and VCC.
6(3) VCC 14(12)
3
ML4664/ML4669
PIN DESCRIPTION (Continued)
PIN NAME FUNCTION PIN NAME FUNCTION
17(15) LMON
Link Monitor "Low Light" LED status output. Pulled low when voltage on the OPINP, OPINN inputs exceed min threshold set by VTHADJ , and there are transitions on OPINP, OPINN indicating an idle signal or active data. If the voltage on OPINP, OPINN inputs falls below the minimum threshold or transitions cease on OPINP, OPINN, LMON will go high. Active low LED driver, open collector. In the low light state, optical and twisted pair transmitters are disabled from sending data. The optical transmitter of the ML4664 does send an idle signal, and link pulses are sent at the twisted pair transmitter. For the ML4669, the twisted pair transmitter will not send link pulses, the optical transmitter may send an idle signal, depending on inputs. See Table 1.
22(21) VREF 23(22) VTHADJ 24(23) AGND 25(24) OPINN
A 2.5V reference with respect to GND This input pin sets the link monitor threshold Analog Filtered Ground This input pin should be capacitively coupled to filtered AVCC. The input resistance is approximately 1.3kW. This input pin should be capacitively coupled to the input source. The input resistance is approximately 1.3kW. Analog Filtered 5V Indicates reception is taking place on the OPINP, OPINN pair. Active low LED driver, open collector. It is extended 16ms for usability. This pin may be grounded to disable the twisted pair outputs. If this pin is not used as an LED driver, and is not grounded, a 2kW, 5% resistor should be connected between this pin and VCC.
26(25) OPINP
27(26) AVCC 28(28) OPLED
18(16) OPVCC 19(17) OPOUT 21(20) VDC
5V supply for fiber optic LED driver Fiber optic LED driver output An external capacitor on this pin integrates an error signal which nulls the offset of the input amplifier. If the DC feedback loop is not being used, this pin should be connected to VREF.
4
ML4664/ML4669
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. Power Supply Voltage Range VCC ................................................................... GND -0.3 to 6V Input Voltage Range: Digital Inputs (SQEN, LBDIS) ....................... GND -0.3 to VCC +0.3V Tx+, Tx-, VIN+, VIN- .............. GND -0.3 to VCC +0.3V Junction Temperature ............................................. 150C Storage Temperature ................................ -65C to 150C Lead Temperature (Soldering) ................................ 260C Thermal Resistance (qJA) PLCC ............................................................... 68C/W TQFP ............................................................... 80C/W
OPERATING CONDITIONS
Temperature Range ML4664/ML4669CX .................................. 0C to 70C ML4664/ML4669IQ ............................... -40C to 85C Supply Voltage (VCC) ......................................... 5V 5% LED on Current ...................................................... 10mA RRSET ........................................................ 61.9kW 1% RTSETOP ....................................................... 115W 1% RTSETTP ........................................................ 220W 1%
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, TA = Operating Temperature Range, VCC = OPVCC = AVCC = 5V 5% (Note 1)
SYMBOL
ICC VREF
PARAMETER
Power Supply Current While Transmitting Reference Voltage
CONDITIONS
RTSETOP = 115W C Suffix I Suffix
MIN
TYP
MAX
140
UNITS
mA V V V mA mA mA
2.30 2.25 1.5 47 46 42 300 450 50 300 4 52
2.60 2.67 3.5 57 58.5
VOL IOPOUT
LED Drivers: VOL OP Transmit Peak Output Current
RL = 300 for OPLED, TPLED, POLLED LTF, and LMON RTSETOP = 115 (Note 2) C Suffix I Suffix
ITPOUT VTPSQ HTP VTPIN RTPIN VOPTH HOP VOPIN ROPIN VOPCM AV VOFF VN ITH
TP Transmit Peak Output Current TP Receive Squelch Voltage TP Receive Squelch Hysteresis TP Receive Input Voltage TP Receive Input Resistance OP Receive Input Threshold Voltage OP Receive Input Threshold Hysteresis OP Receive Input Voltage OP Receive Input Resistance OP Receive Common Mode Voltage Amplifier Gain Input Offset Input Referred Noise Input Bias Current at VTHADJ
RTSETTP = 220
585
mVP-P %
3100
mVP-P kW
VTHADJ = VREF
5
6 20
7
mVP-P %
2 0.8 1.3 1.65 100 VDC = VREF (DC Loop Inactive) 50MHz Bandwidth VTHADJ = VREF -200 3 25 0
1600 2.0
mVP-P kW V V/V mV V
200
A
5
ML4664/ML4669
ELECTRICAL CHARACTERISTICS (Continued)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS OP TO TP (SEE FIGURE 1)
tTPODY tTPSDY tTPSPW tPS Twisted Pair Start-up Delay Twisted Pair Steady State Delay Twisted Pair Turn Off Pulse Width Twisted Pair Jitter 180 3.5 500 35 ns ns ns ns
TP TO OP (SEE FIGURE 2)
tOPODY tOPSDY tOPDI 1/tIDF PIDC tOPJ Optical Transmit Start-up Delay Steady State Delay Turn Off Width from Data to Idle Idle Frequency Idle Duty Cycle Jitter into 31W Load 400 0.85 45 500 15 2100 1.25 55 1.5 ns ns ns MHz % ns
OPTICAL LINK VERIFICATION (SEE FIGURES 3-5)
tOLL tOLM tOLO No Light (No Transitions) to LMON High Low Light (Below Threshold) to LMON High Light On (Above Threshold, Transitions <3s) to LMON Low 3 50 0.25 100 0.5 10 200 0.75 s s s
TWISTED PAIR LINK VERIFICATION (SEE FIGURE 6)
tLT tLTMIN tLTMAX Link Loss Time Link Time Minimum Link Time Maximum 50 2 25 150 7 150 ms ms ms
LINK PULSE TRANSMIT (SEE FIGURE 7)
tLPRR tLPW Link Pulse Rep Rate Link Pulse Width 8 85 16 120 24 200 ms ns
LED TIMING (SEE FIGURE 8)
tLED LED on Time 8 16 32 ms
Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions. Note 2: The output current may be increased to 100mA by changing the RTSETOP resistor for the CQ (PLCC) package option only. See equation (1) on page 9. The increased current option is not available for the CH (TQFP) package option.
6
ML4664/ML4669
OPINP OPINN
VALID tTPODY
DATA tTPSPW tTPSDY VALID DATA
TPOUTP TPOUTN
Figure 1. OP to TP Timing Diagram
TPINP TPINN tOPODY I(OPOUT) tOPSDY tOPDI tIDF
Figure 2. TP to OP Timing Diagram
OPINP OPINN tOLL LMON
Figure 3. Optical Link Verification No Light Timing Diagram
OPINP OPINN
VTH
tOLM LMON
Figure 4. Optical Link Verification Low Light Timing Diagram
7
ML4664/ML4669
OPINP OPINN tOLO LMON
Figure 5. Optical Link Verification Light On Timing Diagram
TPINP TPINN VALID DATA OR LINK PULSE LTF tLT
tLTMIN, tLTMAX TPINP TPINN
Figure 6. Twisted Pair Link Verification Timing Diagram
TPOUTP TPOUTN tLPW tLPRR
Figure 7. Link Pulse Transmit Timing Diagram
TPINP, TPINN OR OPINP, OPINN
VALID
DATA
tLED TPLED OR OPLED
Figure 8. LED Timing Diagram
8
ML4664/ML4669
SYSTEM DESCRIPTION
OPTICAL TRANSMISSION
The optical transmit function consists of detecting the presence of data from the TP inputs TPINP and TPINN and driving that data onto the fiber optic LED transmitter. A positive signal on the TPINP lead relative to the TPINN lead will result in no current, hence the fiber optic LED is in a low light condition. When TPINP is more negative than TPINN, the ML4664/ML4669 will sink current into the chip and the fiber optic LED will light up. Before data will be transmitted onto the fiber optic cable it must exceed the squelch requirements. The TP inputs, squelch circuit serves the function of preventing any noise from being transmitted onto the fiber. 2. All continuous sinusoidal signals of amplitude less than 6.2VP-P and frequency less than 2MHz. 3. All single sinusoidal cycles of amplitude less than 6.2VP-P and either polarity, where the frequency is between 2MHz and 15MHz. For a period of 4 BT before and after this single cycle, the signal will conform to (1) above. 4. All sinusoidal cycles gated by a 100ns pulse gate of amplitude less than 6.2VP-P and either polarity, where the sinusoidal frequency is between 2MHz and 30MHz. The off time of the pulse gate on the sinusoidal signal shall be at least 400ns. The first three receive squelch criteria are required to conform to the 10BASE-T standard. The fourth receive squelch criteria exceeds the 10BASE-T requirements and enhances performance. The fourth squelch criteria prevents a false unsquelch caused by cross talk or noise typically found coupling from the phone lines onto the receive twisted pair. After the TP inputs are unsquelched, the detection threshold is lowered to 225mV. Upon passing the TP squelch requirements the receive data passes to the LED Driver. The addition of jitter through the TP to OP path is no more than 1.5ns. While in the unsquelch state, the TP squelch circuit looks for the start of idle signal at the end of the packet. When start of idle is detected, TP squelch is turned on again. The proper start of idle occurs when the input signal remains above 300mV for 160ns.
FIBER OPTIC LED DRIVER
The output stage of the transmitter is a current mode switch which develops the output light by sinking current through the LED into the OPOUT pin. Once the current requirement for the LED is determined, the RTSETOP resistor is selected. The following equation is used to select the correct RTSETOP resistor:
RTSETOP =
52mA 115W I
OUT
(1)
The ML4664/ML4669 optical transmitter (in the PLCC package only) is capable of driving up to 100mA maximum which requires resistor RSTETOP to equal 60W. (This option is only available with the PLCC package) The transmitter enters the idle state when it detects start of idle on TPINP and TPINN input pins. After detecting the start of idle the transmitter switches to a 1MHz output idle signal. The output current is switched through the OPOUT pin during the on cycle and the OPVCC pin during the off cycle. Since the sum of the current in these two pins is constant, OPVCC should be connected as close as possible to the VCC connection for the LED.
LINK TEST FUNCTION
Transmission -- Whenever data is not being delivered to the twisted pair link, the idle signal is applied. The idle signal is a sequence of Link Pulses separated by a 16ms period of silence. The idle signal starts with a period of silence after a packet transmission ends. The link test pulse is a single high pulse with the same amplitude requirements as the data signal. Reception -- The transceiver monitors the receive twisted pair input for packet and link pulse activity. If neither a packet nor a link test pulse is received for 50 to 150ms, the transceiver enters the Link Test Fail state and inhibits transmission and reception. Link pulses received with the wrong polarity will be ignored and cause the chip to go into link test fail. When a packet, or five consecutive link test pulses is received from the twisted pair input, the transceiver will exit the Link Test Fail state upon transmit and receive data being idle, and re-enable transmission and reception.
TP SQUELCH
The twisted pair receive data is transformer coupled and low pass filtered before it is fed into the input pins TPINP and TPINN. The input is differential with the common mode voltage internally set. At the start of packet reception from the twisted pair link, no more than 5 bits are received from the twisted pair cable and not transmitted. The first bit sent at the optical transmitter may contain phase violations or invalid data, but all subsequent bits are valid. The TP squelch will reject the following signals on the TPINP and TPINN inputs: 1. All signals that produce a peak magnitude less than 300mV (450mV typical).
9
ML4664/ML4669
SYSTEM DESCRIPTION (Continued)
Link test pulses that do not occur within at most 25 to 150ms of each other are not considered consecutive. In addition, detected pulses that occur within a time between 2 to 7ms of a previous pulse will be considered as noise by the link test circuitry, and will reset the count of consecutive link pulses to zero. If the ML4664 enters the link test fail state, both link pulses at the twisted pair transmitter, and idle at the optical transmitter will continue to be sent. Data will not be sent at either transmitter. If the ML4669 enters the link test fail state, idle will not be sent at the optical transmitter. Data will not be sent at either transmitter. However, link pulses may still be sent at the twisted pair transmitter, depending on the optical inputs. See Table 1. The POLDIS status pin is updated only when four consecutive frames are received with the same Start of Idle polarity. In the case where the part is powered up with the receive polarity reversed and no frames are received, the part will go into link test fail without reflecting a reverse polarity condition. If five consecutive revised link pulses are then received, the polarity will reverse and the device will come out of Link Test Fail.
TP TRANSMISSION
The TP transmit function consists of detecting the presence of data from the OP inputs, OPINP and OPINN and driving that data onto the transmit twisted pair (TPOUTP, TPOUTN). A positive signal on the OPINP lead relative to the OPINN lead will result in a positive signal on the TPOUTP lead of the chip with respect to the TPOUTN lead. Before data will be transmitted onto the twisted pair from the OP inputs, it must exceed the squelch requirements for the OP inputs. The OP squelch circuit serves the function of preventing any noise from being transmitted onto the twisted pair. The output stage of the transmitter is a current mode switch which develops the output voltage by driving current through the terminating resistor and the output filter. The transmitter employs a center tap 2:1 transformer where the center tap is tied to VCC (+5V). While one pin of the transmit pair (TPOUTP, TPOUTN) is pulled low, the other pin floats. The output pins to the twisted pair wires,
POLARLITY CIRCUITRY
The ML4664/ML4669 offers automatic polarity correction. The POLDIS pin is used to report the status of the receive pair polarity. This pin is high when the polarity is correct, and low when the polarity is reversed. If this pin is grounded, the polarity correction circuit is disabled. Polarity Detection -- The internal circuitry uses the start of idle signal to determine the receive polarity. With the correct receive polarity, the Start of Idle signal (the end of the frame) will remain above 300mV for more than 160ns. If the polarity is reversed, the Start of Idle signal will end with a negative voltage.
BINARY
0
1
1
1
0
0
1
1
0
TxTP+ TxTP-
OUTPUT AFTER TRANSMIT FILTER
INPUT INTO RECEIVER
Figure 9. Transmit Pre-Equalization Waveform
10
ML4664/ML4669
SYSTEM DESCRIPTION (Continued)
TPOUTP and TPOUTN, can drive a 100W, 150W load, or a variety of impedances that are characteristic of the twisted pair wire. RTSETTP selects the current into the TPOUTP, TPOUTN pins. This current along with the characteristic impedance of the cable determines the output voltage. Once the characteristic impedance of the twisted pair is determined, one must select the appropriate RTSETTP resistor as well as match the terminating impedances of the transmit and receive filter. The RTSETTP resistor can be selected as follows:
RTSETTP =
While in the unsquelch state, the receive squelch circuit looks for the start of idle signal at the end of the packet. Start of idle occurs when the input signal remains idle for more than 160ns. When start of idle is detected, the receive squelch circuit returns to the squelch state and the start of idle signal is output on the twisted pair outputs TPOUTP, TPOUTN.
INPUT AMPLIFIER
The OPINP, OPINN input signal is fed into a limiting amplifier with a gain of about 100 and input resistance of 1.3kW. Maximum sensitivity is achieved through the use of a DC restoration feedback loop and AC coupling the input. When AC coupled, the input DC bias voltage is set by an on-chip network at about 1.7V. These coupling capacitors, in conjunction with the input impedance of the amplifier, establish a high pass filter with 3dB corner frequency, fL, at: fL = 1 2p 1300 C (3)
R 220W 100
L
(2)
Where RL is the characteristic impedance of the twisted pair cable. The transmitter incorporates a pre-equalization circuit for driving the twisted pair line. Pre-equalization compensates for the amplitude and phase distortion introduced by the twisted pair cable. The twisted pair line will attenuate the 10MHz signal more than the 5MHz signal. Therefore pre-equalization insures that both the 5 and 10MHz components will be roughly the same amplitude at the far end receiver. The pre-equalization circuit reduces the current output when a 5MHz bit is being transmitted. After 50ns of a 5MHz bit, the current level is reduced to approximately 2/3 of its peak for the remaining 50ns. Figure 9 illustrates the pre-equalization. An on-chip one-shot determines the pulse width of the pre-equalized transmit signal. This requires an external capacitor connected to pins TxCAP0 and TxCAP1. The proper value for this one-shot is 680pF. Pre-equalization can be disabled by shorting TxCAP0 and TxCAP1 together. The transmitter enters the idle state when it detects start of idle on OPINP and OPINN input pins. The transmitter maintains a minimum differential output voltage of at least 450mV for 250ns after the last low to high transition. The driver differential output voltage will then be within 50mV of 0V within 45 bit times.
Since the amplifier has a differential input, two capacitors of equal value are required. If the signal driving the input is single ended, one of the coupling capacitors can be tied to AVCC. The internal amplifier has a lowpass filter built-in to band limit the input signal which in turn will improve the signal to noise ratio. Although the input is AC coupled, the offset voltage within the amplifier will be present at the amplifier's output. In order to reduce this error a DC feedback loop is incorporated. This negative feedback loop nulls the offset voltage, forcing VOS to be zero. Although the capacitor on VDC is non-critical, the pole it creates can effect the stability of the feedback loop. To avoid stability problems, the value of this capacitor should be at least 10 times larger than the input coupling capacitors. The comparator is a high-speed differential zero crossing detector that slices and accurately digitizes the receive signal. The output of the comparator is fed into the receive squelch circuit.
OP SQUELCH
The input to the optical receiver comes from a fiber optic pre-amp. At the start of packet reception no more than 2.7 bits are received from the fiber cable and not transmitted onto the TP outputs. The receive squelch will reject frequencies lower than 2.51MHz.
11
ML4664/ML4669
VREF R1 R2
REF
VTHADJ
THRESH GEN
Figure 10.
INPUTS
OUTPUTS
STATUS LEDS
TPIN
None LPS Data None LPS Data None LPS Data
OPIN
None None None Idle Idle Idle Data Data Data
OPOUT
None (Idle) Idle Idle None (Idle) Idle Data None (Idle) Idle Data
TPOUT
None (LPS) None (LPS) None (LPS) LPS LPS LPS LPS Data Data
LTF
OFF ON ON OFF ON ON OFF ON ON
LMON OFF OFF OFF ON ON ON ON ON ON
TPLED OPLED
OFF OFF ON OFF OFF ON OFF OFF ON OFF OFF OFF OFF OFF OFF ON ON ON
LPS = Link Pulses ON = Low OFF = High Some simplifications made regarding LMON and LTF state machines, see system description.
Table 1. ML4669 Functionality. Differences in parentheses are for the ML4664.
12
ML4664/ML4669
SYSTEM DESCRIPTION (Continued)
OPTICAL LINK DETECT CIRCUIT AND LOW LIGHT
The link detect circuit monitors the input signal and determines when the input falls below a preset voltage level. When the input falls below a preset voltage, the ML4664/ML4669 goes into the Low Light state. In the Low Light state the TP transmitter is disabled, but continues sending link pulses, the receiver is disabled, and the LMON LED pin goes to high shutting off the LMON LED. To return to the Link Pass state, the optical receiver power must be 20% higher than the shut-off state. This built-in hysteresis adds stability to the Link Monitor circuit. Once the receiver power threshold is exceeded, the ML4664/ML4669 waits 250ms to 750ms, then checks to see that no data is being received before re-enabling the transmitter, and receiver, and lighting up the LMON LED. When the ML4664 is in the low light state, both the link pulses at the twisted pair transmitter and idle at the optical transmitter continue to be sent. However, when the ML4669 is in the low light state, link pulses are not sent at the twisted pair transmitter. Data is not sent at either transmitter. An idle signal may be sent at the optical transmitter, depending on the twisted pair inputs. See Table 1. The VTHADJ pin is used to adjust the sensitivity of the receiver. The ML4664/ML4669 is capable of exceeding the 10BASE-FL specifications for sensitivity. The sensitivity is dependent on the layout of the PC board. A good low noise layout will exceed the 10BASE-FL specifications, while a poor layout will fail to meet the sensitivity and BER spec. The threshold generator shifts the reference voltage at VTHADJ through a circuit which has a temperature coefficient matching that of the limiting amplifier. The relationship between the VTHADJ and the VTH (the peak to peak input threshold) is: case the Link Detect circuit must not disable the receiver (i.e. VTHADJ should be tied to 1.0V). Once the sensitivity of the receiver is determined, VTHADJ can be set just above the power level that meets the BER specification. This way the receiver will shut-off before the BER is exceeded. For 10BASE-FL VTHADJ can be tied directly to VREF. However if greater sensitivity is required the circuit in Figure 10 can be used to adjust the VTHADJ voltage. Even if VREF is tied to VTHADJ, it is a good idea to layout a board with these two resistors available. This will allow potential future adjustments without board revisions. The response time of the Link Detect circuit is set by the CTIMER pin. Starting from the link off state the link can be switched on if the input exceeds the set threshold for a time given by:
T=
CTIMER 0.7V 700mA
(5)
To switch the link from on to off, the above time will be doubled. A value of 0.05F will meet to 10BASE-FL specifications.
LED DRIVERS
The ML4664/ML4669 has five LED drivers. The LED driver pins are active low, and the LEDs are normally off (except for LTF and LMON). The LEDs are tied to their respective pins through a 300W resistor to 5 Volts. The OPLED and TPLED pins have pulse stretchers on them which enables the LEDs to be visible. If another event occurs before the timer expires, the LED timer will reset and restart the timing. Therefore rapid events will leave the LEDs continuously on. The LMON, LTF, and POLDIS LEDs do not have a pulse stretcher on since its condition occurs long enough for the eye to see.
VTHADJ = 408VTH
(4)
LOW LIGHT CONDITION
The LMON LED output is used to indicate a low light condition. LMON is activated low when both the receive power exceeds the Link Monitor threshold and there are transitions on OPINP, OPINN less than 3s apart. If either one of these conditions do not exist, LMON will go high.
A 10BASE-FL receiver must make less than 1 x 10-9 bit errors at a receive power level of -32.5dBm average. One procedure to determine the sensitivity of a receiver is to start at the lowest optical power level and gradually increase the optical power until the BER is met. In this
13
ML4664/ML4669
VCC L2* 5V C9 33F C8 0.1F L1** R12 510 GND VCC R5 330 TF # OP # R6 330 POL DIS # R7 330 TP # R4 330 LMON # # Panasonic LNI4161C-(TR) LEDs C12 0.1F R8 330 * L1, L2: Fair-rite 2743019447 Ferrite beads + C11 33F FILTERED VCC C10 0.1F
PWR
J1 28 OPLED J2 2
J4 12 POLDIS
J3 3 TPLED 17 LMON OPVCC 18 19 16 R2 115 R1 61.9k C1 0.047F C2 0.1F
VCC
2
6
C7 7 0.1F
LTF OPOUTP RTSETOP
3
HFBR1414/ OPC1414
VCC R14 50 8 7 9 P1 3 6 RJ45 1 19 14 12 VALOR SF1301 OR BEL S556-2793-00 OR 2 R15 200 11 TPOUTP ML4664 U1 0.1F 4 5 TPINP TPINN R13 50
R17 1k FILTERED VCC
RRSET 15
CTIMER
1
VDC
21
OPINN
25
C5 0.01F
R11 10
C6 0.1F
17 EQUIVALENT 3 2 2:1 (TX) 1:1 (RX) R16 200 4 10 7 C3 680pF R3 220 VCC 8 13 TxCAP1 RTSETTP GND 9 GND 20 AGND 24 TPOUTN TxCAP0
OPINP VREF
26 22
C4 0.01F
6 2 1 4 R9 5 6 HFBR2416/ OPC2416
VTHADJ
23 FILTERED VCC
AVCC VCC VCC
27 6 14
7 R10*
3
VCC
*R10: Optional to increase the sensitivity. On this EVAL Board R9 is shorted and R10 is open.
Figure 11. Typical Application Circuit.
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ML4664/ML4669
PHYSICAL DIMENSIONS inches (millimeters)
Package: Q28 28-Pin PLCC
0.485 - 0.495 (12.32 - 12.57) 0.450 - 0.456 (11.43 - 11.58) 1 0.042 - 0.056 (1.07 - 1.42) 0.025 - 0.045 (0.63 - 1.14) (RADIUS)
0.042 - 0.048 (1.07 - 1.22)
PIN 1 ID 8 22 0.450 - 0.456 0.485 - 0.495 (11.43 - 11.58) (12.32 - 12.57) 0.300 BSC (7.62 BSC) 0.390 - 0.430 (9.90 - 10.92)
15 0.050 BSC (1.27 BSC) 0.026 - 0.032 (0.66 - 0.81) 0.165 - 0.180 (4.06 - 4.57) 0.148 - 0.156 (3.76 - 3.96) 0.009 - 0.011 (0.23 - 0.28)
0.099 - 0.110 (2.51 - 2.79)
0.013 - 0.021 (0.33 - 0.53)
SEATING PLANE
Package: H32-7 32-Pin (7 x 7 x 1mm) TQFP
0.354 BSC (9.00 BSC) 0.276 BSC (7.00 BSC) 25 0 - 8 0.003 - 0.008 (0.09 - 0.20)
1 PIN 1 ID 0.276 BSC (7.00 BSC) 0.354 BSC (9.00 BSC)
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0.018 - 0.030 (0.45 - 0.75)
9 0.032 BSC (0.8 BSC) 0.012 - 0.018 (0.29 - 0.45) 0.048 MAX (1.20 MAX) 0.037 - 0.041 (0.95 - 1.05) SEATING PLANE
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ML4664/ML4669
ORDERING INFORMATION
PART NUMBER
ML4664CH (Obsolete) ML4664CQ ML4664IQ (Obsolete) ML4669CH ML4669CQ ML4669IQ (Obsolete)
TEMPERATURE
0C to 70C 0C to 70C -40C to 85C 0C to 70C 0C to 70C -40C to 85C
PACKAGE
32-Pin TQFP(H32-7) Molded 28-Pin PLCC (Q28) Molded 28-Pin PLCC (Q28) 32-Pin TQFP(H32-7) Molded 28-Pin PLCC (Q28) Molded 28-Pin PLCC (Q28)
(c) Micro Linear 1998.
is a registered trademark of Micro Linear Corporation. All other trademarks are the property of their respective owners.
DS4664_69-01 2092 Concourse Drive San Jose, CA 95131 Tel: 408/433-5200 Fax: 408/432-0295 www.microlinear.com
8/28/98 Printed in U.S.A.
Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376; 5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174; 5,767,653; 5,777,514. Japan: 2,598,946; 2,619,299; 2,704,176. Other patents are pending. Micro Linear reserves the right to make changes to any product herein to improve reliability, function or design. Micro Linear does not assume any liability arising out of the application or use of any product described herein, neither does it convey any license under its patent right nor the rights of others. The circuits contained in this data sheet are offered as possible applications only. Micro Linear makes no warranties or representations as to whether the illustrated circuits infringe any intellectual property rights of others, and will accept no responsibility or liability for use of any application herein. The customer is urged to consult with appropriate legal counsel before deciding on a particular application.
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