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19-3641; Rev 1; 10/07
Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers
General Description
The MAX9234/MAX9236/MAX9238 deserialize three LVDS serial-data inputs into 21 single-ended LVCMOS/LVTTL outputs. A parallel-rate LVDS clock received with the LVDS data streams provides timing for deserialization. The outputs have a separate supply, allowing 1.8V to 5V output logic levels. All these devices are hot-swappable and allow "on-the-fly" frequency programming. The MAX9234/MAX9236/MAX9238 feature DC balance, which allows isolation between a serializer and deserializer using AC-coupling. Each deserializer decodes data transmitted by one of the MAX9209/MAX9211/ MAX9213/MAX9215 serializers. The MAX9234 has a rising-edge output strobe. The MAX9236/MAX9238 have a falling-edge output strobe. The MAX9234/MAX9236/MAX9238 operate in DCbalanced mode only. The MAX9234/MAX9236 operate with a parallel input clock of 8MHz to 34MHz, while the MAX9238 operates from 16MHz to 66MHz. The transition time of the singleended outputs is increased on the low-frequency version parts (MAX9234/MAX9236) for reduced EMI. The LVDS inputs meet ISO 10605 ESD specification, 25kV for AirGap Discharge and 8kV Contact Discharge. The MAX9234/MAX9236/MAX9238 are available in 48-pin TSSOP packages and operate over the -40C to +85C temperature range.
Features
DC Balance Allows AC-Coupling for Wider Input Common-Mode Voltage Range On-the-Fly Frequency Programming Operating Frequency Range 8MHz to 34MHz (MAX9234/MAX9236) 16MHz to 66MHz (MAX9238) Falling-Edge Output Strobe (MAX9236/MAX9238) Slower Output Transitions for Reduced EMI (MAX9234/MAX9236) High-Impedance Outputs when PWRDWN Is Low Allow Output Busing 5V-Tolerant PWRDWN Input PLL Requires No External Components Up to 1.386Gbps Throughput Separate Output Supply Pins Allow Interface to 1.8V, 2.5V, 3.3V, and 5V Logic LVDS Inputs Meet ISO 10605 ESD Requirements LVDS Inputs Conform to ANSI TIA/EIA-644 LVDS Standard Low-Profile, 48-Lead TSSOP Package +3.3V Main Power Supply -40C to +85C Operating Temperature Range
MAX9234/MAX9236/MAX9238
Applications
Automotive Navigation Systems Automotive DVD Entertainment Systems Digital Copiers Laser Printers
Ordering Information
PART MAX9234EUM MAX9236EUM MAX9238EUM TEMP RANGE -40C to +85C -40C to +85C -40C to +85C PINPACKAGE 48 TSSOP 48 TSSOP 48 TSSOP PKG CODE U48-1 U48-1 U48-1
Functional Diagram and Pin Configuration appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers MAX9234/MAX9236/MAX9238
ABSOLUTE MAXIMUM RATINGS
VCC to GND ...........................................................-0.5V to +4.0V VCCO to GND.........................................................-0.5V to +6.0V RxIN_, RxCLK IN_ to GND ....................................-0.5V to +4.0V PWRDWN to GND....................................................-0.5V to 6.0V RxOUT_, RxCLK OUT to GND ................-0.5V to (VCCO + 0.5V) Continuous Power Dissipation (TA = +70C) 48-Pin TSSOP (derate 16mW/C above +70C) ....... 1282mW Storage Temperature Range .............................-65C to +150C Junction Temperature ......................................................+150C ESD Protection Human Body Model (RD = 1.5k, CS = 100pF) All Pins to GND ........................................................5kV IEC 61000-4-2 (RD = 330, CS = 150pF) Contact Discharge (RxIN_, RxCLK IN_) to GND .........8kV Air-Gap Discharge (RxIN_, RxCLK IN_) to GND .......15kV ISO 10605 (RD = 2k, CS = 330pF) Contact Discharge (RxIN_, RxCLK IN_) to GND ........8kV Air Discharge (RxIN_, RxCLK IN_) to GND ...............25kV Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to +3.6V, VCCO = +3.0V to +5.5V, PWRDWN = high, differential input voltage VID = 0.05V to 1.2V, input commonmode voltage VCM = VID/2 to 2.4V - VID/2, TA = -40C to +85C, unless otherwise noted. Typical values are at VCC = VCCO = +3.3V, VID = 0.2V, VCM = 1.25V, TA = +25C.) (Notes 1, 2)
PARAMETER High-Level Input Voltage Low-Level Input Voltage Input Current Input Clamp Voltage SYMBOL VIH VIL IIN VCL VIN = high or low ICL = -18mA VCCO 0.1 RxCLK OUT High-Level Output Voltage VOH IOH = -2mA MAX9238 IOL = 100A Low-Level Output Voltage VOL IOL = 2mA MAX9234/ MAX9236 MAX9238 High-Impedance Output Current IOZ PWRDWN = low, VOUT_ = -0.3V to VCCO + 0.3V VCCO = 3.0V to 3.6V, VOUT = 0 IOS VCCO = 4.5V to 5.5V, VOUT = 0 MAX9234/ MAX9236 MAX9238 MAX9234/ MAX9236 MAX9238 RxCLK OUT RxOUT_ RxCLK OUT RxOUT_ -20 -10 -5 -10 -28 -14 -28 RxCLK OUT RxOUT_ MAX9234/ MAX9236 RxOUT_ VCCO 0.25 V VCCO 0.40 VCCO 0.25 0.1 0.2 0.26 0.2 +20 -40 -20 -40 -75 -37 -75 mA A V CONDITIONS MIN 2.0 -0.3 -70 TYP MAX 5.5 +0.8 +70 -1.5 UNITS V V A V SINGLE-ENDED INPUT (PWRDWN)
SINGLE-ENDED OUTPUTS (RxOUT_, RxCLK OUT) IOH = -100A
Output Short-Circuit Current (Note: Short one output at a time.)
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.0V to +3.6V, VCCO = +3.0V to +5.5V, PWRDWN = high, differential input voltage VID = 0.05V to 1.2V, input commonmode voltage VCM = VID/2 to 2.4V - VID/2, TA = -40C to +85C, unless otherwise noted. Typical values are at VCC = VCCO = +3.3V, VID = 0.2V, VCM = 1.25V, TA = +25C.) (Notes 1, 2)
PARAMETER LVDS INPUTS Differential Input-High Threshold Differential Input-Low Threshold Input Current Power-Off Input Current Input Resistor 1 POWER SUPPLY 8MHz CL = 8pF, worst-case pattern; VCC = VCCO = 3.0V to 3.6V, Figure 2 PWRDWN = low MAX9234/ MAX9236 16MHz 34MHz 16MHz MAX9238 34MHz 66MHz Power-Down Supply Current ICCZ 42 57 98 63 106 177 50 A mA VTH VTL IIN+, IINIINO+, IINORIN1 PWRDWN = high or low VCC = VCCO = 0 or open, PWRDWN = 0 or open PWRDWN = high or low (Figure 1) VCC = VCCO = 0 or open (Figure 1) -50 -25 -40 42 +25 +40 78 50 mV mV A A k SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX9234/MAX9236/MAX9238
Worst-Case Supply Current
ICCW
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers MAX9234/MAX9236/MAX9238
AC ELECTRICAL CHARACTERISTICS
(VCC = VCCO = +3.0V to +3.6V, 100mVP-P at 200kHz supply noise, CL = 8pF, PWRDWN = high, differential input voltage VID = 0.1V to 1.2V, input common mode voltage VCM = VID/2 to 2.4V - VID/2, TA = -40C to +85C, unless otherwise noted. Typical values are at VCC = VCCO = +3.3V, VID = 0.2V, VCM = 1.25V, TA = +25C.) (Notes 3, 4, 5)
PARAMETER Output Rise Time SYMBOL CLHT 0.1VCCO to 0.9VCCO, Figure 3 0.9VCCO to 0.1VCCO, Figure 3 CONDITIONS MAX9234/ MAX9236 MAX9238 MAX9234/ MAX9236 MAX9238 8MHz RxIN Skew Margin RSKM Figure 4 (Note 6) MAX9238 RxCLK OUT High Time RxCLK OUT Low Time RxOUT Setup to RxCLK OUT RxOUT Hold from RxCLK OUT RxCLK IN to RxCLK OUT Delay Deserializer Phase-Locked Loop Set Deserializer Power-Down Delay RCOH RCOL RSRC RHRC RCCD RPLLS RPDD Figures 5a, 5b Figures 5a, 5b Figures 5a, 5b Figures 5a, 5b Figures 6a, 6b Figure 7 Figure 8 16MHz 34MHz 66MHz RxOUT RxCLK OUT RxOUT RxCLK OUT MIN 3.52 2.2 2.2 1.95 1.3 1.3 6600 2560 900 330 0.35 x RCOP 0.35 x RCOP 0.30 x RCOP 0.45 x RCOP 4.9 6.17 8.1 32800 x RCIP 100 TYP 5.04 3.15 3.15 3.18 2.12 2.12 7044 3137 1327 685 ns ns ns ns ns ns ns ps MAX 6.24 3.9 3.9 4.35 2.9 2.9 ns ns UNITS
Output Fall Time
CHLT
Note 1: Current into a pin is defined as positive. Current out of a pin is defined as negative. All voltages are referenced to ground except VTH and VTL. Note 2: Maximum and minimum limits overtemperature are guaranteed by design and characterization. Devices are production tested at TA = +25C. Note 3: AC parameters are guaranteed by design and characterization, and are not production tested. Limits are set at 6 sigma. Note 4: CL includes probe and test jig capacitance. Note 5: RCIP is the period of RxCLK IN. RCOP is the period of RxCLK OUT. RCIP = RCOP. Note 6: RSKM measured with 150ps cycle-to-cycle jitter on RxCLK IN.
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers
Typical Operating Characteristics
(VCC = VCCO = +3.3V, CL = 8pF, PWRDWN = high, differential input voltage VID = 0.2V, input common-mode voltage VCM = 1.2V, TA = +25C, unless otherwise noted.)
MAX9234/MAX9236/MAX9238
MAX9234/MAX9236 WORST-CASE PATTERN AND PRBS SUPPLY CURRENT vs. FREQUENCY
MAX9234/6/8 toc01
MAX9238 WORST-CASE PATTERN AND PRBS SUPPLY CURRENT vs. FREQUENCY
MAX9234/6/8 toc02
100 90 SUPPLY CURRENT (mA) 80 WORST CASE 70 60 27 - 1 PRBS 50 40 30 5 10 15 20 25 30 35
180 160 SUPPLY CURRENT (mA) 140 120 100 80 60 40 27 - 1 PRBS
WORST CASE
40
10
20
30
40
50
60
70
FREQUENCY (MHz)
FREQUENCY (MHz)
MAX9234/MAX9236 RxOUT TRANSITION TIME vs. OUTPUT SUPPLY VOLTAGE (VCCO)
MAX9234/6/8 toc03
MAX9238 RxOUT TRANSITION TIME vs. OUTPUT SUPPLY VOLTAGE (VCCO)
MAX9234/6/8 toc04
7 6 CLHT 5 4 CHLT 3 2 1 2.5 3.0 3.5 4.0 4.5
5
OUTPUT TRANSITION TIME (ns)
OUTPUT TRANSITION TIME (ns)
4 CLHT 3
2 CHLT 1
0 5.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT SUPPLY VOLTAGE (V) OUTPUT SUPPLY VOLTAGE (V)
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers MAX9234/MAX9236/MAX9238
Pin Description
PIN 1, 2, 4, 5, 45, 46, 47 3, 25, 32, 38, 44 6 7, 13, 18 8 9 10 11 12 14 15 16 17 19, 21 20 22 23 24, 26, 27, 29, 30, 31, 33 28, 36, 48 34, 35, 37, 39, 40, 41, 43 42 NAME RxOUT14-RxOUT20 Channel 2 Single-Ended Outputs GND N.C. LVDS GND RxIN0RxIN0+ RxIN1RxIN1+ LVDS VCC RxIN2RxIN2+ RxCLK INRxCLK IN+ PLL GND PLL VCC PWRDWN RxCLK OUT RxOUT0-RxOUT6 VCCO Ground No Connection LVDS Ground Inverting Channel 0 LVDS Serial-Data Input Noninverting Channel 0 LVDS Serial-Data Input Inverting Channel 1 LVDS Serial-Data Input Noninverting Channel 1 LVDS Serial-Data Input LVDS Supply Voltage. Bypass to LVDS GND with 0.1F and 0.001F capacitors in parallel as close to LVDS VCC as possible, with the smallest value capacitor closest to the supply pin. Inverting Channel 2 LVDS Serial-Data Input Noninverting Channel 2 LVDS Serial-Data Input Inverting LVDS Parallel Rate Clock Input Noninverting LVDS Parallel Rate Clock Input PLL Ground PLL Supply Voltage. Bypass to PLL GND with 0.1F and 0.001F capacitors in parallel as close to PLL VCC as possible, with the smallest value capacitor closest to the supply pin. 5V Tolerant LVTTL/LVCMOS Power-Down Input. Internally pulled down to GND. Outputs are high impedance when PWRDWN = low or open. Parallel Rate Clock Single-Ended Output. The MAX9234 has a rising-edge strobe. The MAX9236/MAX9238 have a falling-edge strobe. Channel 0 Single-Ended Outputs Output Supply Voltage. Bypass to GND with 0.1F and 0.001F capacitors in parallel as close to VCCO as possible, with the smallest value capacitor closest to the supply pin. FUNCTION
RxOUT7-RxOUT13 Channel 1 Single-Ended Outputs VCC Digital Supply Voltage. Bypass to GND with 0.1F and 0.001F capacitors in parallel as close to VCC as possible, with the smallest value capacitor closest to the supply pin.
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers
Table 1. Part Equivalent Table
PART MAX9234 MAX9236 MAX9238 EQUIVALENT WITH DCB/NC = HIGH OR OPEN MAX9210 MAX9220 MAX9222 OPERATING FREQUENCY (MHz) 8 to 34 8 to 34 16 to 66 OUTPUT STROBE Rising edge Falling edge Falling edge
MAX9234/MAX9236/MAX9238
Detailed Description
The MAX9234/MAX9236 operate at a parallel clock frequency of 8MHz to 34MHz. The MAX9238 operates at a parallel clock frequency of 16MHz to 66MHz. The transition times of the single-ended outputs are increased on the MAX9234/MAX9236 for reduced EMI.
DC Balance
Data coding by the MAX9209/MAX9211/MAX9213/ MAX9215 serializers (which are companion devices to the MAX9234/MAX9236/MAX9238 deserializers) limits the imbalance of ones and zeros transmitted on each channel. If +1 is assigned to each binary 1 transmitted and -1 is assigned to each binary 0 transmitted, the variation in the running sum of assigned values is called the digital sum variation (DSV). The maximum DSV for the data channels is 10. At most, 10 more zeros than ones, or 10 more ones than zeros, are transmitted. The maximum DSV for the clock channel is five. Limiting the DSV and choosing the correct coupling capacitors maintains differential signal amplitude and reduces jitter due to droop on AC-coupled links. To obtain DC balance on the data channels, the serializer parallel data is inverted or not inverted, depending on the sign of the digital sum at the word boundary. Two complementary bits are appended to each group of 7 parallel input data bits to indicate to the MAX9234/ MAX9236/MAX9238 deserializers whether the data bits are inverted (see Figure 9). The deserializer restores the original state of the parallel data. The LVDS clock signal alternates duty cycles of 4/9 and 5/9, which maintain DC balance.
link (2.4V - 1.425V = 0.975V and 1.075V - 0V = 1.075V). Common-mode voltage differences may be due to ground potential variation or common-mode noise. If there is more than 1V of difference, the receiver is not guaranteed to read the input signal correctly and may cause bit errors. AC-coupling filters low-frequency ground shifts and common-mode noise and passes high-frequency data. A common-mode voltage difference up to the voltage rating of the coupling capacitor (minus half the differential swing) is tolerated. DC-balanced coding of the data is required to maintain the differential signal amplitude and limit jitter on an AC-coupled link. A capacitor in series with each output of the LVDS driver is sufficient for AC-coupling. However, two capacitors--one at the serializer output and one at the deserializer input--provide protection in case either end of the cable is shorted to a high voltage.
RxIN_ + OR RxCLK IN+
RIN1 1.2V
RIN1
RxIN_ - OR RxCLK IN-
Figure 1. LVDS Input Circuit
RCIP RxCLK OUT
AC-Coupling Benefits
Bit errors experienced with DC-coupling can be eliminated by increasing the receiver common-mode voltage range by AC-coupling. AC-coupling increases the common-mode voltage range of an LVDS receiver to nearly the voltage rating of the capacitor. The typical LVDS driver output is 350mV centered on an offset voltage of 1.25V, making single-ended output voltages of 1.425V and 1.075V. An LVDS receiver accepts signals from 0 to 2.4V, allowing approximately 1V common-mode difference between the driver and receiver on a DC-coupled
ODD RxOUT EVEN RxOUT
RISING-EDGE STROBE SHOWN.
Figure 2. Worst-Case Test Pattern 7
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers MAX9234/MAX9236/MAX9238
90% 90%
RxOUT_ OR RxCLK OUT
RxOUT_ OR RxCLK OUT 8pF
10%
10%
CLHT
CHLT
Figure 3. Output Load and Transition Times
IDEAL SERIAL BIT TIME 1.3V
RxCLK IN
VID = 0 RCCD
1.1V RSKM IDEAL MIN MAX RSKM IDEAL
1.5V RxCLK OUT
Figure 6a. MAX9234 Clock-IN to Clock-OUT Delay
+
INTERNAL STROBE
Figure 4. LVDS Receiver Input Skew Margin
RxCLK IN -
VID = 0
RCCD
RCIP RxCLK OUT 0.8V
RxCLK OUT 1.5V
2.0V 0.8V RCOL RSRC
2.0V RCOH RHRC 2.0V 0.8V
2.0V
Figure 6b. MAX9236/MAX9238 Clock-IN to Clock-OUT Delay
RxOUT_
2.0V 0.8V
2V PWRDWN 3V
Figure 5a. MAX9234 Output Setup/Hold and High/Low Times
RCIP VCC RPLLS RxCLK OUT 2.0V 0.8V RCOH RSRC RxOUT_ 2.0V 0.8V 2.0V 0.8V RCOL RHRC 2.0V 0.8V RxCLK OUT 0.8V RxCLK IN
HIGH-Z
Figure 5b. MAX9236/MAX9238 Output Setup/Hold and High/Low Times 8
Figure 7. Phase-Locked Loop Set Time
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers
PWRDWN
Applications Information
Selection of AC-Coupling Capacitors
0.8V
MAX9234/MAX9236/MAX9238
RxCLK IN
RPDD RxOUT_ RxCLK OUT HIGH-Z
Voltage droop and the DSV of transmitted symbols cause signal transitions to start from different voltage levels. Because the transition time is finite, starting the signal transition from different voltage levels causes timing jitter. The time constant for an AC-coupled link needs to be chosen to reduce droop and jitter to an acceptable level. The RC network for an AC-coupled link consists of the LVDS receiver termination resistor (RT), the LVDS driver output resistor (RO), and the series AC-coupling capacitors (C). The RC time constant for two equal-value series capacitors is (C x (RT + RO)) / 2 (Figure 10). The RC time constant for four equal-value series capacitors is (C x (RT + RO)) / 4 (Figure 11). RT is required to match the transmission line impedance (usually 100) and RO is determined by the LVDS driver design (the minimum differential output resistance of 78 for the MAX9209/MAX9211/MAX9213/ MAX9215 serializers is used in the following example). This leaves the capacitor selection to change the system time constant.
Figure 8. Power-Down Delay
MAX9234/MAX9236/MAX9238 vs. MAX9210/MAX9220/MAX9222
The MAX9234/MAX9236/MAX9238 operate in DC-balance mode only. Pinouts are the same as the MAX9210/MAX9220/MAX9222 except that pin 6 on the MAX9234/MAX9236/MAX9238 is no connect (N.C.). DC balance allows AC-coupling with series capacitors. The MAX9234/MAX9236/MAX9238 are hot-swappable and the input frequency can be changed on the fly, but otherwise the specifications and functionality are the same as the MAX9210/MAX9220/MAX9222 operating in DCbalance mode. See Table 1.
+ RxCLK IN CYCLE N - 1 DCA2 RxIN2 DCB2 TxIN20 TxIN19 TxIN18 CYCLE N TxIN17 TxIN16 TxIN15 TxIN14 DCA2 DCB2 TxIN20 TxIN19 TxIN18 CYCLE N + 1 TxIN17 TxIN16 TxIN15 TxIN14
DCA1 RxIN1
DCB1
TxIN13
TxIN12
TxIN11
TxIN10
TxIN9
TxIN8
TxIN7
DCA1
DCB1
TxIN13
TxIN12
TxIN11
TxIN10
TxIN9
TxIN8
TxIN7
DCA0 RxIN0
DCB0
TxIN6
TxIN5
TxIN4
TxIN3
TxIN2
TxIN1
TxIN0
DCA0
DCB0
TxIN6
TxIN5
TxIN4
TxIN3
TxIN2
TxIN1
TxIN0
TxIN_, DCA_, AND DCB_ ARE DATA FROM THE SERIALIZER.
Figure 9. Deserializer Serial Input
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers MAX9234/MAX9236/MAX9238
MAX9209 MAX9211 MAX9213 MAX9215 MAX9234 MAX9236 MAX9238
HIGH-FREQUENCY, CERAMIC SURFACE-MOUNT CAPACITORS CAN ALSO BE PLACED AT THE SERIALIZER INSTEAD OF THE DESERIALIZER. TxOUT RxIN
7 (7 + 2):1 100 1:(9 - 2)
7
7 TxIN (7 + 2):1 100 1:(9 - 2)
7 RxOUT
7 (7 + 2):1 100 1:(9 - 2)
7
PWRDWN PLL TxCLK IN TxCLK OUT 21:3 SERIALIZER RxCLK IN 3:21 DESERIALIZER 100 PLL
PWRDWN RxCLK OUT
Figure 10. Two Capacitors per Link, AC-Coupled
MAX9209 MAX9211 MAX9213 MAX9215
HIGH-FREQUENCY CERAMIC SURFACE-MOUNT CAPACITORS
MAX9234 MAX9236 MAX9238
TxOUT 7 (7 + 2):1 100
RxIN 7 1:(9 - 2)
7 TxIN (7 + 2):1 100 1:(9 - 2)
7 RxOUT
7 (7 + 2):1 100 1:(9 - 2)
7
PWRDWN PLL TxCLK IN TxCLK OUT 21:3 SERIALIZER RxCLK IN 3:21 DESERIALIZER 100 PLL
PWRDWN RxCLK OUT
Figure 11. Four Capacitors per Link, AC-Coupled 10 ______________________________________________________________________________________
Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers
In the following example, the capacitor value for a droop of 2% is calculated. Jitter due to this droop is then calculated assuming a 1ns transition time: C = - (2 x tB x DSV) / (ln (1 - D) x (RT + RO)) (Eq 1) where: C = AC-coupling capacitor (F). tB = bit time (s). DSV = digital sum variation (integer). ln = natural log. D = droop (% of signal amplitude). RT = termination resistor (). RO = output resistance (). Equation 1 is for two series capacitors (Figure 10). The bit time (tB) is the period of the parallel clock divided by 9. The DSV is 10. See equation 3 for four series capacitors (Figure 11). The capacitor for 2% maximum droop at 8MHz parallel rate clock is: C = - (2 x tB x DSV) / (ln (1 - D) x (RT + RO)) C = - (2 x 13.9ns x 10) / (ln (1 - 0.02) x (100 + 78)) C = 0.0773F Jitter due to droop is proportional to the droop and transition time: tJ = tT x D (Eq 2) where: tJ = jitter (s). tT = transition time (s) (0 to 100%). D = droop (% of signal amplitude). Jitter due to 2% droop and assumed 1ns transition time is: tJ = 1ns x 0.02 tJ = 20ps The transition time in a real system depends on the frequency response of the cable driven by the serializer. The capacitor value decreases for a higher frequency parallel clock and for higher levels of droop and jitter. Use high-frequency, surface-mount ceramic capacitors. Equation 1 altered for four series capacitors (Figure 11) is: C = - (4 x tB x DSV) / (ln (1 - D) x (RT + RO)) (Eq 3) pullup resistor between the noninverting input and VCC, and a 10k 1% pulldown resistor between the inverting input and ground. These bias resistors, along with the 100 1% tolerance termination resistor, provide +15mV of differential input.
MAX9234/MAX9236/MAX9238
Unused LVDS Data Inputs
At each unused LVDS data input, pull the inverting input up to VCC using a 10k resistor, and pull the noninverting input down to ground using a 10k resistor. Do not connect a termination resistor. The pullup and pulldown resistors drive the corresponding outputs low and prevent switching due to noise.
PWRDWN
Driving PWRDWN low puts the outputs in high impedance, stops the PLL, and reduces supply current to 50A or less. Driving PWRDWN high drives the outputs low until the PLL locks. The outputs of two deserializers can be bused to form a 2:1 mux with the outputs controlled by PWRDWN. Wait 100ns between disabling one deserializer (driving PWRDWN low) and enabling the second one (driving PWRDWN high) to avoid contention of the bused outputs.
Input Clock and PLL Lock Time
There is no required timing sequence for the application or reapplication of the parallel rate clock (RxCLK IN) relative to PWRDWN, or to a power-supply ramp for proper PLL lock. The PLL lock time is set by an internal counter. The maximum time to lock is 32,800 clock periods. Power and clock should be stable to meet the lock-time specification. When the PLL is locking, the outputs are low.
Power-Supply Bypassing
There are separate on-chip power domains for digital circuits, outputs, PLL, and LVDS inputs. Bypass each VCC, VCCO, PLL VCC, and LVDS VCC pin with high-frequency, surface-mount ceramic 0.1F and 0.001F capacitors in parallel as close to the device as possible, with the smallest value capacitor closest to the supply pin.
Cables and Connectors
Interconnect for LVDS typically has a differential impedance of 100. Use cables and connectors that have matched differential impedance to minimize impedance discontinuities. Twisted-pair and shielded twisted-pair cables offer superior signal quality compared to ribbon cable and tend to generate less EMI due to magnetic field canceling effects. Balanced cables pick up noise as common mode, which is rejected by the LVDS receiver.
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Input Bias and Frequency Detection
The inverting and noninverting LVDS inputs are internally connected to +1.2V through 42k (min) to provide biasing for AC-coupling (Figure 1). A frequency-detection circuit on the clock input detects when the input is not switching, or is switching at low frequency. In this case, all outputs are driven low. To prevent switching due to noise when the clock input is not driven, bias the clock input to differential +15mV by connecting a 10k 1%
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Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers MAX9234/MAX9236/MAX9238
Board Layout
Keep the LVTTL/LVCMOS outputs and LVDS input signals separated to prevent crosstalk. A four-layer PC board with separate layers for power, ground, LVDS inputs, and digital signals is recommended.
R1 1M CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE CS 100pF R2 1.5k DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST
ESD Protection
The MAX9234/MAX9236/MAX9238 ESD tolerance is rated for IEC 61000-4-2 Human Body Model and ISO 10605 standards. IEC 61000-4-2 and ISO 10605 specifiy ESD tolerance for electronic systems. The Human Body Model discharge components are CS = 100pF and RD = 1.5k (Figure 12). For the Human Body Model, all pins are rated for 5kV contact discharge. The ISO 10605 discharge components are CS = 330pF and RD = 2k (Figure 13). For ISO 10605, the LVDS outputs are rated for 8kV contact and 25kV air discharge. The IEC 61000-4-2 discharge components are CS = 150pF and RD = 330 (Figure 14). For IEC 61000-4-2, the LVDS inputs are rated for 8kV Contact Discharge and 15kV Air-Gap Discharge.
Figure 12. Human Body ESD Test Circuit
R1 50 TO 100 CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE CS 330pF
R2 2k DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST
5V Tolerant Input
PWRDWN is 5V tolerant and is internally pulled down to GND.
Skew Margin (RSKM)
Skew margin (RSKM) is the time allowed for degradation of the serial data sampling setup and hold times by sources other than the deserializer. The deserializer sampling uncertainty is accounted for and does not need to be subtracted from RSKM. The main outside contributors of jitter and skew that subtract from RSKM are interconnect intersymbol interference, serializer pulse position uncertainty, and pair-to-pair path skew.
Figure 13. ISO 10605 Contact Discharge ESD Test Circuit
50 TO 100 CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE CS 150pF
RD 330 DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST
VCCO Output Supply and Power Dissipation
The outputs have a separate supply (VCCO) for interfacing to systems with 1.8V to 5V nominal input-logic levels. The DC Electrical Characteristics table gives the maximum supply current for VCCO = 3.6V with 8pF load at several switching frequencies with all outputs switching in the worst-case switching pattern. The approximate incremental supply current for VCCO other than 3.6V with the same 8pF load and worst-case pattern can be calculated using: II = CTVI 0.5fC x 21 (data outputs) + CTVIfC x 1 (clock output) where: II = incremental supply current. CT = total internal (CINT) and external (CL) load capacitance. VI = incremental supply voltage. fC = output clock-switching frequency.
Figure 14. IEC 61000-4-2 Contact Discharge ESD Test Circuit
The incremental current is added to (for VCCO > 3.6V) or subtracted from (for VCCO < 3.6V) the DC Electrical Characteristics table maximum supply current. The internal output buffer capacitance is CINT = 6pF. The worst-case pattern-switching frequency of the data outputs is half the switching frequency of the output clock. In the following example, the incremental supply current is calculated for VCCO = 5.5V, fC = 34MHz, and CL = 8pF: VI = 5.5V - 3.6V = 1.9V CT = CINT + CL = 6pF + 8pF = 14pF
12
______________________________________________________________________________________
Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers
where: II = CTVI 0.5FC x 21 (data outputs) + CTVIfC x 1 (clock output). II = (14pF x 1.9V x 0.5 x 34MHz x 21) + (14pF x 1.9V x 34MHz). II = 9.5mA + 0.9mA = 10.4mA. The maximum supply current in DC-balanced mode for VCC = VCCO = 3.6V at fC = 34MHz is 106mA (from the DC Electrical Characteristics table). Add 10.4mA to get the total approximate maximum supply current at VCCO = 5.5V and VCC = 3.6V. If the output supply voltage is less than VCCO = 3.6V, the reduced supply current can be calculated using the same formula and method. At high switching frequency, high supply voltage, and high capacitive loading, power dissipation can exceed the package power-dissipation rating. Do not exceed the maximum package power-dissipation rating. See the Absolute Maximum Ratings for maximum package power-dissipation capacity and temperature derating.
Rising- or Falling-Edge Output Strobe
The MAX9234 has a rising-edge output strobe, which latches the parallel output data into the next chip on the rising edge of RxCLK OUT. The MAX9236/MAX9238 have a falling-edge output strobe, which latches the parallel output data into the next chip on the falling edge of RxCLK OUT. The deserializer output strobe polarity does not need to match the serializer input strobe polarity. A deserializer with rising- or fallingedge output strobe can be driven by a serializer with a rising-edge input strobe.
MAX9234/MAX9236/MAX9238
Pin Configuration
TOP VIEW
RxOUT17 1 RxOUT18 2 GND 3 RxOUT19 4 RxOUT20 5
48 47 46 45 44 43 42 41
VCCO RxOUT16 RxOUT15 RxOUT14 GND RxOUT13 VCC RxOUT12 RxOUT11 RxOUT10 GND RxOUT9 VCCO RxOUT8 RxOUT7 RxOUT6 GND RxOUT5 RxOUT4 RxOUT3 VCCO RxOUT2 RxOUT1 GND
Functional Diagram
LVDS DATA RECEIVER 0 RxIN0+ RxIN0LVDS DATA RECEIVER 1 RxIN1+ RxIN1LVDS DATA RECEIVER 2 RxIN2+ RxIN2LVDS CLOCK RECEIVER RxCLK IN+ RxCLK IN9x PLL REFERENCE CLOCK GENERATOR STROBE STROBE STROBE DATA CHANNEL 0 SERIAL-TOPARALLEL CONVERTER DATA CHANNEL 1 SERIAL-TOPARALLEL CONVERTER DATA CHANNEL 2 SERIAL-TOPARALLEL CONVERTER RxOUT14-20 RxOUT7-13 RxOUT0-6
N.C. 6 LVDS GND 7 RxIN0- 8 RxIN0+ 9 RxIN1- 10 RxIN1+ 11 LVDS VCC 12 LVDS GND 13 RxIN2- 14 RxIN2+ RxCLK INRxCLK IN+ 15 16 17
MAX9234 MAX9236 MAX9238
40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25
LVDS GND 18 PLL GND 19
PLL VCC 20 PLL GND 21
PWRDWN 22
RxCLK OUT
RxCLK OUT
23
RxOUT0 24
TSSOP
PWRDWN
Chip Information
MAX9234 TRANSISTOR COUNT: 14,104 MAX9236 TRANSISTOR COUNT: 14,104 MAX9238 TRANSISTOR COUNT: 14,104 PROCESS: CMOS
______________________________________________________________________________________ 13
Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers MAX9234/MAX9236/MAX9238
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
48L TSSOP.EPS
E H
N
MARKING
AAA A
123
TOP VIEW
BOTTOM VIEW
SEE DETAIL A
b A1 A2 e D
SEATING PLANE
A
C L
c
END VIEW
SIDE VIEW
( )
PARTING LINE
b b1
WITH PLATING
0.25 L
DETAIL A
c1
BASE METAL
c
NOTES: 1. DIMENSIONS D & E ARE REFERENCE DATUMS AND DO NOT INCLUDE MOLD FLASH. 2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED 0.15MM ON D SIDE, AND 0.25MM ON E SIDE. 3. CONTROLLING DIMENSION: MILLIMETERS. 4. THIS PART IS COMPLIANT WITH JEDEC SPECIFICATION MO-153, VARIATIONS, ED (48L), EE (56L). 5. "N" REFERS TO NUMBER OF LEADS. 6. THE LEAD TIPS MUST LIE WITHIN A SPECIFIED ZONE. THIS TOLERANCE ZONE IS DEFINED BY TWO PARALLEL PLANES. ONE PLANE IS THE SEATING PLANE, DATUM (-C-), THE OTHER PLANE IS AT THE SPECIFIED DISTANCE FROM (-C-) IN THE DIRECTION INDICATED. 7. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY. 8. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY.
SECTION C-C
PACKAGE OUTLINE, 48 & 56L TSSOP, 6.1mm BODY
21-0155
C
1 1
14
______________________________________________________________________________________
Hot-Swappable, 21-Bit, DC-Balanced LVDS Deserializers
Revision History
REVISION NUMBER 0 1 REVISION DATE 4/05 10/07 Initial release Added IEC 61000-4-2 ESD Performance; various style changes DESCRIPTION PAGES CHANGED -- 1, 2, 4, 5, 6, 12
MAX9234/MAX9236/MAX9238
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 (c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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