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19-4030; Rev 1; 8/08
DisplayPort/PCIe Passive Switches
General Description
The MAX4928A/MAX4928B high-speed passive switches route PCI Express(R) (PCIe) data and/or DisplayPortTM signals between two possible destinations in desktop or laptop PCs. The MAX4928A is intended to be used with the ATX form factor desktop PCs, while the MAX4928B is expected to be used in the BTX form factor. The MAX4928A/MAX4928B are hex double-pole/double-throw (6 x DPDT) switches. The MAX4928A/ MAX4928B feature a single digital control input (SEL) to switch signal paths and a latch input (LE) that holds the switches in a given state. The MAX4928A/MAX4928B are fully specified to operate from a single +3.3V (typ) power supply. The MAX4928A/MAX4928B are available in an industry standard 5mm x 11mm, 56-pin TQFN package. Both devices operate over the -40C to +85C extended temperature range. Single +3.3V Power Supply Voltage Supports PCIe Gen I, Gen II, and DisplayPort Data Rates > 5Gbps Excellent Return Loss > 12dB at 2.5GHz Six Bidirectional Pairs of Switches All Switching in One Device Low 850A (max) Supply Current Small 5mm x 11mm, 56-Pin TQFN Package Industry-Standard Pinouts
Features
MAX4928A/MAX4928B
Ordering Information
PART MAX4928AETN+ MAX4928BETN+ TEMP RANGE -40C to +85F -40C to +85F PIN-PACKAGE 56 TQFN-EP 56 TQFN-EP
Applications
Desktop PCs Notebook PCs
PCI Express is a registered trademark of PCI-SIG. DisplayPort is a trademark of Video Electronics Standards Association (VESA).
+Denotes a lead-free package/RoHS-Compliant package. EP = Exposed paddle.
Typical Operating Circuit appears at end of data sheet.
Pin Configurations
TX1+ TX0+ TX1GND TX0GND VDD VDD D1+ VDD D0+ 56 55 54 53 52 51 50 49 GND IN0+ IN0IN1+ IN1VDD IN2+ IN2IN3+ 1 2 3 4 5 6 7 8 9 48 GND 47 TX2+ 46 TX245 TX3+ 44 TX343 D0+ 42 D041 D1+ 40 D139 D2+ GND SEL LE IN0+ IN0VDD IN1+ IN1IN2+ 1 2 3 4 5 6 7 8 9 + 56 55 54 53 52 51 50 49 48 GND 47 D2+ 46 D245 D3+ 44 D343 TX0+ 42 TX041 TX1+ 40 TX139 TX2+ + D0VDD D1TOP VIEW GND GND 38 TX237 TX3+ 36 TX335 GND 34 VDD 33 AUX+ 32 AUX31 HPD1 *EP 21 22 23 24 25 26 27 28 VDD RX1RX0+ RX0RX1+ GND GND VDD 30 HPD2 29 GND
IN3- 10 GND 11 OUT+ 12 OUT- 13 X+ 14 X- 15 GND 16 VDD 17 SEL 18 LE 19 GND 20 21 22 23 24 25 26 27 28 HPD2 VDD AUXHPD1 AUX+ GND GND VDD *EP
IN2- 10 GND 11 IN3+ 12 IN3- 13 OUT+ 14 OUT- 15 GND 16 VDD 17 X+ 18 X- 19 GND 20
MAX4928A
38 D237 D3+ 36 D335 GND 34 VDD 33 RX0+ 32 RX031 RX1+ 30 RX129 GND
MAX4928B
*CONNECT EXPOSED PADDLE TO GND.
TQFN
TQFN
________________________________________________________________ Maxim Integrated Products
1
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DisplayPort/PCIe Passive Switches MAX4928A/MAX4928B
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND, unless otherwise noted.) VDD ...........................................................................-0.3V to +4V LE, SEL, IN_, X_, OUT_, D_, TX_, HPD_, RX_, AUX_ (Note 1) ...............................................-0.3V to + (VDD + 0.3V) |VIN_ - VTX_|, |VIN_ - VD_|, |VX_ - VHPD_|, |VX_ - VRX1_|, |VOUT_ - VAUX_|, |VOUT_ - VRX0_| (Note 1) ...................0 to +2V Continuous Current (IN_ to D_/TX_, X_ to HPD_/RX1_, OUT_ to AUX_/RX0_ .....................................................70mA Peak Current (IN_ to D_/TX_, X_ to HPD_/RX1_, OUT_ to AUX_/RX0_) (pulsed at 1ms, 10% duty cycle) .............70mA Continuous Current (LE, SEL)...........................................30mA Peak Current (LE, SEL) (pulsed at 1ms, 10% duty cycle)..................................70mA Continuous Power Dissipation (TA = +70C) for Multilayer Board 56-Pin TQFN (derate 41.0mW/C above +70C) .......3279mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Package Junction-to-Ambient Thermal Resistance (JA) (Note 2) .....................................................................24.4C/W Package Junction-to-Case Thermal Resistance (JC) (Note 2) .......................................................................1.5C/W Lead Temperature (soldering) .........................................+300C
Note 1: Signals on IN_, X_, OUT_, D_, TX_, HPD_, RX_, or AUX_, LE, SEL exceeding VDD or GND are clamped by internal diodes. Limit forward-diode current to maximum current rating. Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a 4-layer board. For detailed information on package thermal considerations, see www.maxim-ic.com/thermal-tutorial.
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.
ELECTRICAL CHARACTERISTICS
(VDD = +3.3V 10%, TA =TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +3.3V, TA = +25C, unless otherwise noted.) (Note 3)
PARAMETER ANALOG SWITCH Analog Signal Range IN_, X_, OUT_, D_, TX_, HPD_, RX_, AUX_ |VIN_ - VTX_|, |VIN_ - VD_|, |VX_ - VHPD_|, |VX_ - VRX1_|, |VOUT_ VAUX_|, |VOUT_ - VRX0_| RON RON IIN_ = IX_ = IOUT_ = 15mA, VD_, VTX_, VHPD_, VAUX_, or VRX_ = 0V, +1.2V VDD = +3.0V, IIN_ = IX_ = IOUT_= 15mA, VD_, VTX_, VHPD_, VAUX_, or VRX_ = 0V (Notes 4, 5) VDD = +3.0V, IIN_ = IX_ = IOUT_= 15mA, VD_, VTX_, VHPD_, VAUX_, or VRX_ = 0V (Notes 4, 5) VDD = +3.0V, IIN_ = IX_ = IOUT_= 15mA, VD_, VTX_, VHPD_, VAUX_, or VRX_ = 0V, +1.2V (Notes 5, 6) -0.1 (VDD 1.8) V SYMBOL CONDITIONS MIN TYP MAX UNITS
Voltage Between IN and D/TX, X and HPD/RX1, and OUT and AUX/RX0
0
1.8
V
On-Resistance On-Resistance Match Between Pairs of Same Channel On-Resistance Match Between Channels
8
0.1
2
RON
1.5
4
On-Resistance Flatness
RFLAT(ON)
0.3
1.5
2
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DisplayPort/PCIe Passive Switches
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +3.3V 10%, TA =TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +3.3V, TA = +25C, unless otherwise noted.) (Note 3)
PARAMETER D_ or TX_/ HPD_ or RX1_/ AUX_ or RX0_ Off-Leakage Current SYMBOL ID_ (OFF) ITX_ (OFF) IHPD_ (OFF) IRX1_ (OFF) IAUX_ (OFF) IRX0_ (OFF) IIN_ (ON) IX_ (ON) IOUT_ (ON) CONDITIONS MIN TYP MAX UNITS
MAX4928A/MAX4928B
VDD = +3.6V , VIN_ = VX_ = VOUT_ = 0V, +1.2V; VD_ or VTX_, VHPD_ or VRX1_, VAUX_ or VRX0_ = +1.2V, 0V
-1
+1
A VDD = +3.6V , VIN_ = VX_ = VOUT_ = 0V, +1.2V; VD_ or VTX_ = VIN_ or unconnected, VHPD_ or VRX1_ = VX_ or unconnected, VAUX_ or VRX0_ = VOUT_ or unconnected VD_ or VTX_ = +1.0V, RL = 50, VHPD_ or VRX1_ = +1.0V, RL = 50, VAUX_ or VRX0_ = +1.0V, RL = 50, LE = VDD, CL = 100pf (Figure 1) VD_ or VTX_ = +1.0V, RL = 50, VHPD_ or VRX1_ = +1.0V, RL = 50, VAUX_ or VRX0_ = +1.0V, RL = 50, LE = VDD, CL = 100pf (Figure 1) VD_ or VTX_ = +1.0V, RL = 50, VHPD_ or VRX1_ = +1.0V, RL = 50, VAUX_ or VRX0_ = +1.0V, RL = 50 (Figure 1) VD_ or VTX_ = +1.0V, RL = 50, VHPD_ or VRX1_ = +1.0V, RL = 50, VAUX_ or VRX0_ = +1.0V, RL = 50, (Figure 1) VD_ or VTX_ = +1.0V, RL = 50, VHPD_ or VRX1_ = +1.0V, RL = 50, VAUX_ or VRX0_ = +1.0V, RL = 50 (Figure 1) f = 2.5GHz f = 5.0GHz f = 7.5GHz f = 2.5GHz
IN_/X_/OUT_ On-Leakage Current
-1
+1
DIGITAL SIGNALS
SEL to Switch Turn-On Time
tON_SEL
55
120
ns
SEL to Switch Turn-Off Time
tOFF_SEL
8
50
ns
LE Setup Time SEL to LE
tSU
2
ns
LE Hold Time SEL to LE
tHOLD
2
ns
LE Minimum Pulse-Width Low
tW
40
ns
-1.5 -3.3 -4.9 -40 -23 -28 -22 -21 -8 -7 dB dB dB dB
Differential Insertion Loss (Figure 2)
SDD21
Differential Crosstalk (Figure 2) Differential Off-Isolation Differential Return Loss (Figure 2)
SDDCTK SDD21_OFF SDD11
f = 5.0GHz f = 7.5GHz f = 3.0GHz f = 2.8GHz f = 5.0GHz f = 7.5GHz
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DisplayPort/PCIe Passive Switches MAX4928A/MAX4928B
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +3.3V 10%, TA =TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +3.3V, TA = +25C, unless otherwise noted.) (Note 3)
PARAMETER Signal Data Rate Differential -3dB Bandwidth LOGIC INPUT (LE, SEL) Input Logic-High Input Logic-Low Input Logic Hysteresis Input Leakage Current POWER SUPPLY Power Supply Range VDD Supply Current VDD IDD VIN = 0 or VDD 3.0 3.6 850 V A VIH VIL VHYST IIN VIN = 0 or VDD -1 100 +1 1.4 0.5 V V mV A SYMBOL BR DBW CONDITIONS RS = RL = 100 balanced RS = RL = 100 balanced MIN TYP 10 5 MAX UNITS Gbps GHz
Note 3: All units are 100% production tested at TA = +85C. Limits over the operating temperature range are guaranteed by design and characterization and are not production tested. Note 4: RON = RON (MAX) - RON (MIN). Note 5: Guaranteed by design. Not production tested. Note 6: Flatness is defined as the difference between the maximum and minimum value of on-resistance as measured over the specified analog signal range.
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DisplayPort/PCIe Passive Switches
Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
MAX4928A/MAX4928B
ON-RESISTANCE vs. VIN_, VX_, VOUT_
MAX4928A/B toc01
ON-RESISTANCE vs. VIN_, VX_, VOUT_
MAX4928A/B toc02
SUPPLY CURRENT vs. TEMPERATURE
900 800 SUPPLY CURRENT (A) 700 600 500 400 300 200 100 0 VDD = 3.3V
MAX4928A/B toc03
10.0 9.5 9.0 ON-RESISTANCE () 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 -0.1 0.1 0.3 0.5 0.7 0.9 1.1 1.3 VDD = 3.3V
10.0 9.5 9.0 ON-RESISTANCE () 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 VDD = 3.3V -0.1 0.1 0.3 0.5 0.7 0.9 1.1 1.3 TA = -40C TA = +25C TA = +85C
1000
1.5
1.5
-40
-15
10
35
60
85
VIN_, VX_, VOUT_ (V)
VIN_, VX_, VOUT_ (V)
TEMPERATURE (C)
LOGIC THRESHOLD vs. SUPPLY VOLTAGE
MAX4928A/B toc04
TURN-ON/OFF TIME vs. SUPPLY VOLTAGE
MAX4928A/B toc05
DIFFERENTIAL INSERTION LOSS
MAX4928A/B toc06
1.5
VDD = 3.3V
100
0 DIFFERENTIAL INSERTION LOSS (dB) -2
1.3 LOGIC THRESHOLD (V) VIH 1.1
80 TURN-ON/OFF TIME (ns)
60
tON_SEL
-4
0.9 VIL 0. 7
40 tOFF_SEL
-6
20
-8
0.5 3.0 3.1 3.2 3.3 3.4 3.5 3.6 SUPPLY VOLTAGE (V)
0 3.0 3.1 3.2 3.3 3.4 3.5 3.6 SUPPLY VOLTAGE (V)
-10 10 100 1,000 10,000 FREQUENCY (MHz)
DIFFERENTIAL OFF-ISOLATION
MAX4928A/B toc07
DIFFERENTIAL CROSSTALK
MAX4928A/B toc08
DIFFERENTIAL RETURN LOSS
MAX4928A/B toc09
0 DIFFERENTIAL OFF-ISOLATION (dB)
0 -20
0 DIFFERENTIAL RETURN LOSS (dB)
DIFFERENTIAL CROSSTALK (dB)
-20
-10
-40
-40
-20
-600
-60
-80
-30
-80 10 100 1,000 10,000 FREQUENCY (MHz)
-100 10 100 1,000 10,000 FREQUENCY (MHz)
-40 10 100 1,000 10,000 FREQUENCY (MHz)
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DisplayPort/PCIe Passive Switches MAX4928A/MAX4928B
Test Circuits/Timing Diagrams
MAX4928A/MAX4928B
+3.3V VDD D_ OR TX_, HPD_ OR RX1_, AUX_ OR RX0_ SEL LOGIC INPUT SEL GND LE LOGIC INPUT LE SWITCH OUTPUT TX_, RX1_, OR RX0_ 0V t ON_SEL t OFF_SEL SWITCH OUTPUT D_, HPD_, OR AUX 0.9 x VOUT 0V t ON_SEL 0.9 x VOUT IN_, X_, OR OUT_ VOUT RL CL VOUT 0.9 x VOUT LOGIC INPUT SEL LOGIC INPUT LE t r < 5ns t f < 5ns
VIH 50% VIL
VN_
t OFF_SEL 0.9 x VOUT
CL INCLUDES FIXTURE AND STRAY CAPACITANCE. RL VOUT = VN_ RL + RON
(
)
VN_ = VD_ OR VTX_, VHPD_ OR VRX1_, VAUX_, OR VRX0_
LOGIC INPUT LE LOGIC INPUT SEL
VIH 50% VIL
tW 50% t SU t HOLD 50%
VIH 50% VIL
Figure 1. Switching Time
6
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DisplayPort/PCIe Passive Switches
Test Circuits/Timing Diagrams (continued)
+3.3V 0.1F NETWORK ANALYZER 50 VDD 0V 50 50 50 D_50 HPD_+ 50 HPD_50 AUX_+ 50 AUX_GND TX_RX1_RX0_TX_+ RX1_+ RX0_+ PORT 3 VOUT+ HPD_+ 50 50 HPD_50 PORT 4 VOUTAUX_+ 50 50 AUX_GND TX_RX1_RX0_TX_+ RX1_+ RX0_+ PORT 3 VOUT+ 50 D_+ MAX4928A MAX4928B IN_X_OUT_SEL LE +3.3V 0.1F NETWORK ANALYZER 50
MAX4928A/MAX4928B
VDD VDD 0V 50 D_+ 50 D_50 MAX4928A MAX4928B IN_X_OUT_SEL LE IN_+ X_+ OUT_+
PORT 1 VIN+
VDD IN_+ X_+ OUT_+
PORT 1 VIN+
PORT 2 VIN-
PORT 2 VIN-
50
PORT 4 VOUT-
50
DIFFERENTIAL INSERTION-LOSS/DIFFERENTIAL RETURN LOSS DIFFERENTIAL INSERTION-LOSS = 20log
DIFFERENTIAL OFF-ISOLATION
(
VOUT+ - VOUTVIN+ - VIN+3.3V
)
0.1F
DIFFERENTIAL OFF-ISOLATION = 20log
(
VOUT+ - VOUTVIN+ - VIN-
)
VDD 0V OR VDD 0V 50 50 50 AUX_+/AUX_50 TX_+/TX_50 50 HP0_+/HP0_GND RX1_+/RX1_IN_X_OUT_IN_+ X_+ OUT_+ D_+/D_- MAX4928A MAX4928B HPD_+/HPD_IN_X_OUT_SEL LE IN_+ X_+ OUT_+
PORT 1 VIN+
NETWORK ANALYZER 50
PORT 2 VIN-
50
PORT 3 VOUT+
50
PORT 4 VOUT-
50
DIFFERENTIAL CROSSTALK DIFFERENTIAL CROSSTALK = 20log
(
VOUT+ - VOUTVIN+ - VIN-
)
MEASUREMENTS ARE STANDARDIZED AGAINST SHORTS AT IC TERMINALS. DIFFERENTIAL OFF-ISOLATION IS MEASURED BETWEEN IN_ AND "OFF" D_ OR TX_, X_ AND "OFF" HPD_ OR RX1_, OUT_ AND "OFF" AUX_ OR RX0_ TERMINAL ON EACH SWITCH. DIFFERENTIAL ON-LOSS IS MEASURED BETWEEN IN_ AND "ON" D_ OR TX_, X_ AND "ON" HPD_ OR RX1_, OUT_ AND "ON" AUX_ OR RX0_ TERMINAL ON EACH SWITCH. DIFFERENTIAL CROSSTALK IS MEASURED BETWEEN ANY TWO PAIRS.
Figure 2. Differential On-Loss, Differential Off-Isolation, and Differential Crosstalk
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DisplayPort/PCIe Passive Switches MAX4928A/MAX4928B
Pin Description
PIN MAX4928A MAX4928B GND IN0+ IN0IN1+ IN1VDD IN2+ IN2IN3+ IN3OUT+ OUTX+ XSEL LE HPD2 HPD1 AUXAUX+ RX1RX1+ RX0RX0+ D3D3+ D2D2+ D1D1+ D0D0+ TX3TX3+ TX2Ground Analog Switch 1--Common Positive Terminal Analog Switch 1--Common Negative Terminal Analog Switch 2--Common Positive Terminal Analog Switch 2--Common Negative Terminal Positive Supply Voltage Input. Connect VDD to a +3.0V to +3.6V supply voltage. Bypass VDD to GND with a 0.1F ceramic capacitor placed as close as possible to the device. See the Board Layout section. Analog Switch 3--Common Positive Terminal Analog Switch 3--Common Negative Terminal Analog Switch 4--Common Positive Terminal Analog Switch 4--Common Negative Terminal Analog Switch 5--Common Positive Terminal Analog Switch 5--Common Negative Terminal Analog Switch 6--Common Positive Terminal Analog Switch 6--Common Negative Terminal Control Signal Input Latch Enable Input Analog Switch 6--Normally Open Negative Terminal Analog Switch 6--Normally Open Positive Terminal Analog Switch 5--Normally Open Negative Terminal Analog Switch 5--Normally Open Positive Terminal Analog Switch 6--Normally Closed Negative Terminal Analog Switch 6--Normally Closed Positive Terminal Analog Switch 5--Normally Closed Negative Terminal Analog Switch 5--Normally Closed Positive Terminal Analog Switch 4--Normally Open Negative Terminal Analog Switch 4--Normally Open Positive Terminal Analog Switch 3--Normally Open Negative Terminal Analog Switch 3--Normally Open Positive Terminal Analog Switch 2--Normally Open Negative Terminal Analog Switch 2--Normally Open Positive Terminal Analog Switch 1--Normally Open Negative Terminal Analog Switch 1--Normally Open Positive Terminal Analog Switch 4--Normally Closed Negative Terminal Analog Switch 4--Normally Closed Positive Terminal Analog Switch 3--Normally Closed Negative Terminal NAME FUNCTION
1, 11, 16, 20, 21, 1, 11, 16, 20, 21, 28, 29, 35, 48, 28, 29, 35, 48, 49, 56 49, 56 2 3 4 5 4 5 7 8
6, 17, 22, 27, 34, 6, 17, 22, 27, 34, 50, 55 50, 55 7 8 9 10 12 13 14 15 18 19 23 24 25 26 30 31 32 33 36 37 38 39 40 41 42 43 44 45 46 9 10 12 13 14 15 18 19 2 3 30 31 32 33 23 24 25 26 44 45 46 47 51 52 53 54 36 37 38
8
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DisplayPort/PCIe Passive Switches
Pin Description (continued)
PIN MAX4928A 47 51 52 53 54 -- MAX4928B 39 40 41 42 43 -- NAME TX2+ TX1TX1+ TX0TX0+ EP FUNCTION Analog Switch 3--Normally Closed Positive Terminal Analog Switch 2--Normally Closed Negative Terminal Analog Switch 2--Normally Closed Positive Terminal Analog Switch 1--Normally Closed Negative Terminal Analog Switch 1--Normally Closed Positive Terminal Exposed Pad. Connect EP to GND. Exposed pad internally connected to GND.
MAX4928A/MAX4928B
Detailed Description
The MAX4928A/MAX4928B high-speed passive switches route PCI Express (PCIe) data and/or DisplayPort signals between two possible destinations. The MAX4928A/ MAX4928B are ideal for routing signals between a graphics memory controller hub (GMCH) and either a DisplayPort or PCIe connector. The MAX4928A/MAX4928B feature a single digital control input (SEL) to switch signal paths and a latch input (LE) that holds the switches in a given state.
IN_- channels are routed to either the D_- or TX_- channels, signals on the X- channel are routed to either HPD2 or RX1- channels, and signals on the OUT- channel are routed to either AUX- or RX0- channels. The MAX4928A/MAX4928B are bidirectional switches, allowing IN_, X_, OUT_, D_, TX_, HPD_, RX_, and AUX_ to be used as either inputs or outputs.
Applications Information
DisplayPort/PCIe Switching
The MAX4928A/MAX4928B primary applications are aimed to switch between a GMCH and either a DisplayPort or PCIe connector. The MAX4928A/ MAX4928B contain n-channel switches to permit differential signals to be selected between a PCIe Gen II socket or to a DisplayPort connector. Each device handles up to six pairs of signals. The DisplayPort signal is an AC-coupled 8b/10b encoded differential signal ranging up to 2.7 Gbps. The PCIe Gen I and Gen II signals are AC-coupled, 8b/10b encoded differential signals ranging up to 5.0Gbps.
Digital Control Input (SEL)
The MAX4928A/MAX4928B provide a single digital control input (SEL) to select the signal path between the IN_ and D_/TX_, X_ and HPD_/RX1_, and OUT_ and AUX_/RX0_ channels. The truth tables for the MAX4928A/MAX4928B are depicted in the Functional Diagrams/Truth Table. Drive SEL rail-to-rail to minimize power consumption.
Latch Control Input (LE)
The MAX4928A/MAX4928B provide a single digital control input (LE) to latch the signal paths between the IN_ and D_/TX_, X_ and HPD_/RX1_, and OUT_ and AUX_/RX0_ channels. When LE is driven high, the switches are held in their previous state, regardless of the input signal to SEL. Drive LE rail-to-rail to minimize power consumption.
Board Layout
High-speed switches require proper layout and design procedures for optimum performance. Keep designcontrolled impedance PCB traces as short as possible or follow impedance layouts per the PCIe specification. Ensure that power-supply bypass capacitors are placed as close as possible to the device. Multiple bypass capacitors are recommended. Connect all grounds and the exposed pad to large ground planes.
Analog Signal Levels
The MAX4928A/MAX4928B accept standard PCIe signals to a maximum of (VDD - 1.8V). Signals on the IN_+ channels are routed to either the D_+ or TX_+ channels, signals on the X+ channel are routed to either HPD1 or RX1+ channels, and signals on the OUT+ channel are routed to either AUX+ or RX0+ channels. Signals on the
Chip Information
PROCESS: CMOS
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9
DisplayPort/PCIe Passive Switches MAX4928A/MAX4928B
Functional Diagram/Truth Table
VDD
MAX4928A MAX4928B IN0+ IN0TX0+ TX0D0+ D0IN1+ IN1TX1+ TX1D1+ D1IN2+ IN2TX2+ TX2D2+ LE 1 0 0 SEL X 0 1 IN_ TO TX_, IN_ TO DO_, X_ TO RX1_, X_ TO HPD_, OUT_ TO RX0_ OUT_ TO AUX_ NO CHANGE ON OFF NO CHANGE OFF ON D2IN3+ IN3TX3+ TX3D3+ D3X+ XRX1+ RX1HPD1 HPD2 OUT+ OUTRX0+ RX0AUX+ AUX-
X = DON'T CARE.
CONTROL SEL LE
LATCH
GND
10
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DisplayPort/PCIe Passive Switches
Typical Operating Circuit
DP CONNECTOR
MAX4928A/MAX4928B
VDD
VCC = 1V GRAPHICS AND MEMORY CONTROLLER HUB MAX4928A MAX4928B D0+ D0D1+ D1D2+ D2D3+ D3HPD1 HPD2 AUX+ AUX-
VCC
D0 D1 D2 D3 D4 D5 D6 D7 HPD AUX AUX
1.5k
PCIe BUFF 1 PCIe BUFF 2 PCIe BUFF 3 PCIe BUFF 4 PCIe IN AUX
IN0+ IN0IN1+ IN1IN2+ IN2IN3+ IN3X+ XOUT+ OUT-
CHANNEL SELECT
SEL LE
TX0+ TX0TX1+ TX1TX2+ TX2TX3+ TX3RX1+ RX1RX0+ RX0-
GND
PCIe GRAPHICS CONNECTOR SUPPLY VOLTAGE VCC = 1V
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N
100k
11
DisplayPort/PCIe Passive Switches MAX4928A/MAX4928B
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 56 TQFN-EP PACKAGE CODE T56511-1 DOCUMENT NO. 21-0187
12
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DisplayPort/PCIe Passive Switches
Revision History
REVISION NUMBER 0 1 REVISION DATE 2/08 8/08 Initial release Changed functional diagram and limits DESCRIPTION PAGES CHANGED -- 1, 2, 11
MAX4928A/MAX4928B
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 ____________________ 13
(c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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