Datasheet

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High Speed, Triple Differential Receiver

with Comparators

AD8145

Rev. A

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FEATURES

High speed: 500 MHz, 2000 V/μs @ G = 1, V

OUT

= 2 V p-p

0.1 dB flatness out to 75 MHz

High CMRR: 69 dB @ 10 MHz

High differential input impedance: 1 MΩ

Wide input common-mode range: ±3.5 V (±5 V supplies)

On-chip, gain setting resistors can be configured for gain of 1 or 2

Fast settling: 15 ns to 0.1% @ 2 V p-p

Low input referred noise: 13 nV/√Hz

Disable feature

Small packaging: 32-lead, 5 mm × 5 mm LFCSP

AEC-Q10 qualified (AD8145W)

APPLICATIONS

RGB video receivers

YPbPr video receivers

Keyboard, video, mouse (KVM)

Unshielded twisted pair (UTP) receivers

Automotive driver assistance (AD8145W)

Automotive Infotainment (AD8145W)

FUNCTIONAL BLOCK DIAGRAM

OUT_G

OUT_B

OUT_R

COMPB_IN+

COMPB_IN–

GND

2526272829303132

S+

GND

S–

DIS/PD

REF_B

GAIN_B

IN+_B

IN–_B

GND

REF_G

AIN_G

IN+_G

IN–_G

REF_R

GAIN_R

GND

COMPB_OUT

COMPA_OUT

COMPA_IN–

COMPA_IN+

IN–_R

IN+_R

GND

9 10111213141516

–

AD8145

6307-001

Figure 1.

GENERAL DESCRIPTION

The AD8145 is a triple, low cost, differential-to-single-ended

receiver specifically designed for receiving red-green-blue (RGB)

video signals over twisted pair cable or differential printed circuit

board (PCB) traces. It can also be used to receive any type of

analog signal or high speed data transmission. Two auxiliary

comparators with hysteresis are provided that can be used to

decode video sync signals, which are encoded on the received

common-mode voltages, to receive digital signals or as general-

purpose comparators. The AD8145 can be used in conjunction

with the AD8133 or AD8134 triple differential drivers to provide a

complete low cost solution for RGB over Category 5 UTP cable

applications, including KVM.

The excellent common-mode rejection (69 dB @ 10 MHz) of

the AD8145 allows for the use of low cost, unshielded twisted

pair cables in noisy environments.

The AD8145 can be configured for a differential-to-single-ended

gain of 1 or 2 by connecting the GAIN_x pin of each channel to

its respective output (G = 1) or connecting it to a reference voltage

(G = 2), which is normally grounded.

A REF_x input is provided on each channel that allows designers to

level shift the output signals.

The AD8145W is the automotive grade version that is qualified

per the AEC-Q100 for use in automotive applications. See the

Automotive Products section for more details.

The AD8145 is available in a 5 mm × 5 mm, 32-lead LFCSP and

is rated to work over the extended industrial temperature range

of −40°C to +105°C.

Summary of content (24 pages)

PAGE 1
High Speed, Triple Differential Receiver with Comparators AD8145 REF_G 2 GAIN_G 3 IN+_G 4 IN–_G 5 REF_R 6 + – R R VS– GND 28 27 26 25 C R C DIS/PD 29 REF_B GAIN_B 30 R 24 GND 23 OUT_B 22 OUT_G 21 OUT_R 20 VS+ 19 COMPB_IN+ 18 COMPB_IN– 17 GND + – R A 9 10 11 12 13 14 15 16 COMPA_IN+ COMPA_IN– COMPA_OUT COMPB_OUT GND – IN–_R 8 R B + GND + – IN+_R 7 C GND GAIN_R AD8145 06307-001 1 IN+_B IN–_B GND GND 31 – RGB video receivers YPbP
PAGE 2
AD8145 TABLE OF CONTENTS Features .............................................................................................. 1 Overview ..................................................................................... 15 Applications ....................................................................................... 1 Basic Closed-Loop Gain Configurations ................................ 15 Functional Block Diagram ..............................................................
PAGE 3
AD8145 SPECIFICATIONS TA = 25°C, VS = ±5 V, REF_x = 0 V, RL = 150 Ω, CL = 2 pF, G = 1, TMIN to TMAX = −40°C to +105°C, unless otherwise noted. Table 1. Parameter DYNAMIC PERFORMANCE −3 dB Bandwidth Bandwidth for 0.
PAGE 4
AD8145 Parameter COMPARATOR PERFORMANCE VOH VOL Input Offset Voltage Hysteresis Width Input Bias Current Propagation Delay, tPLH Propagation Delay, tPHL Rise Time Fall Time POWER-DOWN PERFORMANCE Power-Down VIH Power-Down VIL Power-Down IIH Power-Down IIL Power-Down Assert Time POWER SUPPLY Operating Range Quiescent Current, Positive Supply Conditions Min Typ RL = 1 kΩ AD8145W only, TMIN to TMAX RL = 1 kΩ AD8145W only, TMIN to TMAX 3.205 2.950 3.310 PSRR, Negative Supply VS+ − 1.65 VS+ − 2.65 0.
PAGE 5
AD8145 TA = 25°C, VS = ±2.5 V, REF_x = 0 V, RL = 1 kΩ, CL = 2 pF, G = 1, TMIN to TMAX = −40°C to +105°C, unless otherwise noted. Table 2. Parameter DYNAMIC PERFORMANCE −3 dB Bandwidth Bandwidth for 0.
PAGE 6
AD8145 Parameter POWER SUPPLY Operating Range Quiescent Current, Positive Supply Conditions Min 4.5 40 AD8145W only, TMIN to TMAX Disabled AD8145W only, TMIN to TMAX Quiescent Current, Negative Supply PSRR, Positive Supply PSRR, Negative Supply Typ AD8145W only, TMIN to TMAX Disabled AD8145W only, TMIN to TMAX DC AD8145W only, TMIN to TMAX DC AD8145W only, TMIN to TMAX Rev. A | Page 6 of 24 13.5 −43.5 −54 −12.
PAGE 7
AD8145 ABSOLUTE MAXIMUM RATINGS MAXIMUM POWER DISSIPATION Table 3. Parameter Supply Voltage Power Dissipation Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10 sec) Junction Temperature Rating 12 V See Figure 2 −65°C to +125°C −40°C to +105°C 300°C 150°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device.
PAGE 8
AD8145 32 31 30 29 28 27 26 25 GND IN–_B IN+_B GAIN_B REF_B DIS/PD VS– GND PIN CONFIGURATION AND FUNCTION DESCRIPTION 1 2 3 4 5 6 7 8 PIN 1 INDICATOR AD8145 TOP VIEW (Not to Scale) 24 23 22 21 20 19 18 17 GND OUT_B OUT_G OUT_R VS+ COMPB_IN+ COMPB_IN– GND NOTES 1. EXPOSED PAD ON UNDERSIDE OF DEVICE MUST BE CONNECTED TO GROUND. 06307-003 GND IN+_R IN–_R COMPA_IN+ COMPA_IN– COMPA_OUT COMPB_OUT GND 9 10 11 12 13 14 15 16 GND REF_G GAIN_G IN+_G IN–_G REF_R GAIN_R GND Figure 3.
PAGE 9
AD8145 TYPICAL PERFORMANCE CHARACTERISTICS Unless otherwise noted, G = 1, RL = 150 Ω, CL = 2 pF, REF_x = midsupply, VS = ±5 V, TA = 25°C. Refer to the circuit in Figure 35. 3 3 2 2 +5V +5V 1 1 0 ±5V –1 GAIN (dB) –2 –3 –1 –2 –3 –4 –4 –5 –5 –6 ±5V –6 10 1000 100 FREQUENCY (MHz) 06307-004 1 Figure 4. Small Signal Frequency Response at Various Power Supplies, G = 1 1000 Figure 7.
PAGE 10
AD8145 3 3 2 2 1 G=1 0 0 –1 –1 GAIN (dB) –2 G=2 –3 G=2 –2 –3 –4 –4 –5 –5 –6 G=1 –6 VOUT = 0.2V p-p VOUT = 2V p-p 10 1 100 1000 FREQUENCY (MHz) –7 06307-010 –7 10 1 100 1000 FREQUENCY (MHz) 06307-013 GAIN (dB) 1 Figure 13. Large Signal Frequency Response at Various Gains Figure 10. Small Signal Frequency Response at Various Gains 1000 0.5 G = 1, VS = +5V 0.4 INPUT VOLTAGE NOISE (nV/ Hz) G = 1, VS = ±5V 0.3 GAIN (dB) 0.2 0.1 0 G = 2, VS = +5V G = 2, VS = ±5V –0.1 –0.
PAGE 11
AD8145 150 1.5 100 1.0 BLACK = +5V GRAY = ±5V 50 0.5 VOLTAGE (V) 0 0 –50 –0.5 –100 –1.0 10 20 30 40 50 60 70 80 90 100 TIME (ns) 06307-016 0 –1.5 Figure 16. Small Signal Transient Response at Various Power Supplies, G = 1 0 10 20 30 60 70 80 90 100 Figure 19. Large Signal Transient Response at Various Power Supplies, G = 1 1.5 100 1.0 BLACK = +5V GRAY = ±5V BLACK = +5V GRAY = ±5V 0.5 VOLTAGE (V) 50 0 0 –50 –0.5 –100 –1.
PAGE 12
AD8145 4000 1.2 0.3 0.8 0.2 0.1 0.4 ERROR 0 0 2500 2000 –0.1 –0.8 –0.2 –1.2 –0.3 –1.6 –0.4 500 –0.5 50 0 0 5 10 15 20 25 30 35 40 45 NEGATIVE SLEW RATE 3000 –0.4 –2.0 POSITIVE SLEW RATE 3500 1500 1000 06307-048 VOLTAGE (V) 0.4 TIME (ns) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT VOLTAGE (V p-p) Figure 22. Settling Time 06307-049 OUTPUT INPUT 4500 SLEW RATE (V/µs) 1.6 0.5 ERROR (%) 2.0 Figure 25. Slew Rate vs.
PAGE 13
AD8145 65 5 RL = OPEN CIRCUIT 60 4 3 ICC (±5V) 2 IEE (±5V) 45 40 35 IEE (±2.5V) 1 0 –1 30 –2 25 –3 ICC (±2.5V) 20 –4 15 –60 –5 +5V OUTPUT +5V 2 × VIN ±5V OUTPUT ±5V 2 × VIN –20 0 20 40 60 80 100 120 TEMPERATURE (°C) 0 10 0 0 –10 –10 PSRR (dB) BLACK = +5V GRAY = ±5V –30 –40 –50 –30 250 300 350 400 450 500 –50 –60 –70 –70 –80 –80 0.1 1 10 100 1000 FREQUENCY (MHz) Figure 29. Positive Power Supply Rejection Ratio (PSRR) vs. Frequency –90 0.01 2.5 2.0 1.
PAGE 14
AD8145 THEORY OF OPERATION The AD8145 amplifiers use an architecture called active feedback, which differs from that of conventional op amps. The most obvious differentiating feature is the presence of two separate pairs of differential inputs compared to a conventional op amp’s single pair. Typically, for the active feedback architecture, one of these input pairs is driven by a differential input signal while the other is used for the feedback.
PAGE 15
AD8145 APPLICATIONS INFORMATION +5V OVERVIEW The AD8145 contains three independent active feedback amplifiers that can be effectively applied as differential line receivers for red-green-blue (RGB) signals or component video signals, such as YPbPr, transmitted over UTP cable.
PAGE 16
AD8145 To achieve unity gain from VREF to VOUT in this configuration, divide VREF by the same factor used in the feedback loop; the divider resistors, RD, need not be the same values used in the internal feedback loop. Figure 35 illustrates this approach. TERMINATING THE INPUT One of the key benefits of the active feedback architecture is the separation that exists between the differential input signal and the feedback network.
PAGE 17
AD8145 INPUT CLAMPING The differential input that is assigned to receive the input signal includes clamping diodes that limit the differential input swing to approximately 5.5 V p-p at 25°C. Because of this, the input and feedback stages should never be interchanged. The supply current drawn by the AD8145 has a strong dependence on the input signal magnitude because the input transconductance stages operate with differential input signals that can be up to a few volts peak-to-peak.
PAGE 18
AD8145 Figure 41 shows a specific example of external common-mode clamping. V+ 2 Broadband power supply decoupling networks should be placed as close as possible to the supply pins. Small surface-mount ceramic capacitors are recommended for these networks, and tantalum capacitors are recommended for bulk supply decoupling. +5V 3 + RS 0.01µF HBAT-540C VIN – RT Minimizing Parasitic Feedback Reactances 1 V– V+ 2 RS HBAT-540C not required.
PAGE 19
AD8145 DRIVING A CAPACITIVE LOAD POWER-DOWN The AD8145 typically drives either high impedance loads over short PCB traces, such as crosspoint switch inputs, or doubly terminated coaxial cables. A gain of 1 is commonly used in the high impedance case because a 6 dB transmission line termination loss is not incurred. A gain of 2 is required when driving cables to compensate for the 6 dB termination loss.
PAGE 20
AD8145 The AD8134 encoding equations are given in Equation 4, Equation 5, and Equation 6. SYNC PULSE EXTRACTION USING COMPARATORS The AD8145 is particularly useful in KVM applications. KVM networks transmit and receive computer video signals that typically comprise red, green, and blue (RGB) video signals and separate horizontal and vertical sync signals.
PAGE 21
AD8145 OUTLINE DIMENSIONS 0.60 MAX 5.00 BSC SQ 0.60 MAX PIN 1 INDICATOR 4.75 BSC SQ 0.50 BSC 0.50 0.40 0.30 0.80 MAX 0.65 TYP 12° MAX 0.30 0.23 0.18 SEATING PLANE 32 1 EXPOSED PAD (BOTTOM VIEW) 17 16 9 3.45 3.30 SQ 3.15 8 0.25 MIN 3.50 REF 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.20 REF FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. COMPLIANT TO JEDEC STANDARDS MO-220-VHHD-2 112408-A TOP VIEW 1.00 0.85 0.
PAGE 22
AD8145 NOTES Rev.
PAGE 23
AD8145 NOTES Rev.