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Ultralow Power SD Video Filter with Load Detection ADA4431-1
FEATURES
Third-order, low-pass video filter 1 dB flatness out to 6 MHz 27 dB rejection at 27 MHz Low quiescent current: 4.7 mA typical Low power-down current: 24 A typical Load detection capability SAG correction Allows use of smaller capacitors in ac-coupled outputs Low supply voltage: 2.5 V to 3.6 V Charge pump Creates a negative voltage from single positive supply Allows capless output coupling with no dc offset Rail-to-rail output High input-to-output isolation in disabled state 89 dB @ 1 MHz Small package 3 mm x 3 mm LFCSP Low 0.55 mm package height Wide operating temperature range: -40C to +85C
PIN CONFIGURATION
13 SAG 15 FB2 14 OUT 16 FB1
+VS 1 IN 2 DIS 3 LDO 4 LPF
LOAD DETECT G=2
12 GND 11 SUBS 10 +VS 9 CAP1
CHARGE PUMP
CAP4 5
CAP3 6
GND 7
CAP2 8
Figure 1.
+VS
0.1F 1 4 SYSTEM CONTROLLER VIDEO DAC/ ENCODER 3 LDO DIS IN +VS 10 +VS
0.1F 16 15 VIDEO OUT
FB1 FB2 OUT
ADA4431-1
x1 x2
APPLICATIONS
Portable media players Portable gaming consoles Cell phones Digital still cameras Portable DVD players Portable video cameras
2
14
LPF
7
GND
SAG
13
CAP4 CAP3 CAP2 CAP1 SUBS GND 5 0.1F 6 8 0.1F 9 11 1.0F 12
06734-002
Figure 2. Typical Application Circuit
GENERAL DESCRIPTION
The ADA4431-1 is a fully integrated video reconstruction filter that combines excellent video specifications with low power consumption, making it ideal for portable video filtering applications. The ADA4431-1 is able to detect whether a video load is present at the output, powering down the device when the load is disconnected. The ADA4431-1 operates on single supplies as low as 2.5 V while providing the dynamic range required by the most demanding video systems. The on-board charge pump provides a virtual negative supply, allowing the video signal to be dc-coupled and the black level to be set to ground, while the sync passes cleanly at 300 mV below ground. When operating with the charge pump off, the ADA4431-1 provides a dc offset to keep the sync tip approximately 100 mV above ground. In addition, the part features SAG correction, which permits the use of smaller capacitors in applications with ac-coupled outputs. The ADA4431-1 is packaged in a low profile 16-lead LFCSP and operates in the industrial temperature range of -40C to +85C.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2007 Analog Devices, Inc. All rights reserved.
06734-001
75
ADA4431-1 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 Pin Configuration............................................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 5 Thermal Resistance ...................................................................... 5 Maximum Power Dissipation ..................................................... 5 ESD Caution.................................................................................. 5 Pin Configuration and Function Descriptions..............................6 Typical Performance Characteristics ..............................................7 Theory of Operation .........................................................................9 Overview ........................................................................................9 Charge Pump Operation ..............................................................9 Load Detect ....................................................................................9 Evaluation Board ............................................................................ 10 Outline Dimensions ....................................................................... 12 Ordering Guide .......................................................................... 12
REVISION HISTORY
8/07--Revision 0: Initial Version
Rev. 0 | Page 2 of 12
ADA4431-1 SPECIFICATIONS
VS = 3.0 V (@ TA = 25C, VIN = 1 V p-p, RL = 150 , DIS = 3.0 V, charge pump on), unless otherwise noted. Table 1.
Parameter ELECTRICAL SPECIFICATIONS Quiescent Supply Current Normal Mode Load Searching Mode Disabled Mode Disable Pin Current Supply Voltage Range Input Voltage Input Resistance Input Capacitance Output Voltage Range Output Offset Voltage Power Supply Rejection Pass-Band Gain Input-to-Output Isolation--Disabled FILTER CHARACTERISTICS -3 dB Bandwidth 1 dB Flatness Out-of-Band Rejection Differential Gain Differential Phase Linear Output Current Group Delay Variation Test Conditions/Comments Min Typ Max Unit
Video load present No video load DIS = 0 V DIS = 3.0 V (enabled and charge pump on) DIS = 0 V (disabled) 2.5 Limited by output range
4.7 0.1 24 3 -17 1.3 10 1 -0.8 to +2.8 -600 42 6.0 89 7.9 6 27 0.7 0.3 40 30
7.2
6 -30 3.6
f = 100 kHz, output referred f = 1 MHz, DIS = 0 V
-650 36 5.7
-560 6.2
mA mA A A A V V M pF V mV dB dB dB MHz MHz dB % Degrees mA ns
7.1 f = 27 MHz Modulated 10 step ramp, sync tip at 0 V Modulated 10 step ramp, sync tip at 0 V f = 100 kHz to 5 MHz 25
9.1
Rev. 0 | Page 3 of 12
ADA4431-1
VS = 3.0 V (@ TA = 25C, VIN = 1 V p-p, RL = 150 , DIS = floating, charge pump off), unless otherwise noted. Table 2.
Parameter ELECTRICAL SPECIFICATIONS Quiescent Supply Current Normal Mode Load Searching Mode Disabled Mode Disable Pin Current Supply Voltage Range Input Voltage Input Resistance Input Capacitance Output Voltage Range Output Offset Voltage Power Supply Rejection Pass-Band Gain Input-to-Output Isolation--Disabled FILTER CHARACTERISTICS -3 dB Bandwidth 1 dB Flatness Out-of-Band Rejection Differential Gain Differential Phase Linear Output Current Group Delay Variation Test Conditions/Comments Min Typ Max Unit
Video load present No video load DIS = 0 V DIS = 0 V 2.5 Limited by output range
1.6 0.1 24 -17 1.3 10 1 0 to 2.8 0.1 48 6.0 89 7.5 6 29 0.4 0.3 40 30
2.2
-30 3.6
0.2 6.2
f = 100 kHz, output referred f = 1 MHz, DIS = 0 V
38 5.8
mA mA A A V V M pF V V dB dB dB MHz MHz dB % Degrees mA ns
6.7 f = 27 MHz Modulated 10 step ramp, sync tip at 0 V Modulated 10 step ramp, sync tip at 0 V f = 100 kHz to 5 MHz 26
8.4
Rev. 0 | Page 4 of 12
ADA4431-1 ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Supply Voltage Power Dissipation Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering 10 sec) Junction Temperature Rating 4.0 V See Figure 3 -65C to +125C -40C to +85C 300C 150C
The power dissipated in the package (PD) is the sum of the quiescent power dissipation and the power dissipated in the package due to the load drive. The quiescent power is the voltage between the supply pins (VS) times the quiescent current (IS). The power dissipated due to the load drive depends upon the particular application. The power due to load drive is calculated by multiplying the load current by the associated voltage drop across the device. RMS voltages and currents must be used in these calculations. Airflow increases heat dissipation, effectively reducing JA. In addition, more metal directly in contact with the package leads and exposed pad from metal traces, through-holes, ground, and power planes reduces the JA. Figure 3 shows the maximum safe power dissipation in the package vs. the ambient temperature for the 16-lead LFCSP package (43C/W) on a JEDEC standard 4-layer board.
5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5
06743-003
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
THERMAL RESISTANCE
MAXIMUM POWER DISSIPATION (W)
JA is specified for the device (including exposed pad) soldered to a high thermal conductivity 2s2p circuit board, as described in EIA/JESD 51-7. The exposed pad is not electrically connected to the device. It is typically soldered to a pad on the PCB that is thermally and electrically connected to an internal ground plane. Table 4. Thermal Resistance
Package Type 16-lead LFCSP-UQ (CP-16-12) JA 43 Unit C/W
MAXIMUM POWER DISSIPATION
The maximum safe power dissipation in the ADA4431-1 package is limited by the associated rise in junction temperature (TJ) on the die. At approximately 150C, which is the glass transition temperature, the plastic changes its properties. Even temporarily exceeding this temperature limit can change the stresses that the package exerts on the die, permanently shifting the parametric performance of the ADA4431-1. Exceeding a junction temperature of 150C for an extended period can result in changes in the silicon devices potentially causing failure.
1.0 -40 -30 -20 -10
0
10
20 30
40
50
60
70 80 90 100
AMBIENT TEMPERATURE (C)
Figure 3. Maximum Power Dissipation vs. Temperature for a 4-Layer Board
ESD CAUTION
Rev. 0 | Page 5 of 12
ADA4431-1 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
13 SAG 15 FB2 14 OUT 16 FB1
+VS 1 IN 2 DIS 3 LDO 4
12 GND
ADA4431-1
TOP VIEW (Not to Scale)
11 SUBS 10 +VS 9 CAP1
CAP4 5
CAP3 6
GND 7
CAP2 8
Figure 4. Pin Configuration
Table 5. Pin Function Descriptions
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Mnemonic +VS IN DIS LDO CAP4 CAP3 GND CAP2 CAP1 +VS SUBS GND SAG OUT FB2 FB1 Description Supply Voltage. Video Input. Disable Pin. High = charge pump on, floating = charge pump off, low = disabled. Load Detect Output. High = video load present. Capacitor 2, Lead 2. Capacitor 2, Lead 1. Ground. Capacitor 1, Lead 2. Capacitor 1, Lead 1. Supply Voltage. Substrate Voltage Pin. Bypass to GND with 1.0 F capacitor. Ground. SAG Feedback Pin. Video Output. Load Detect Feedback Pin 2. Connect to device side of series termination resistor. Load Detect Feedback Pin 1. Connect to load side of series termination resistor.
Rev. 0 | Page 6 of 12
06743-004
ADA4431-1 TYPICAL PERFORMANCE CHARACTERISTICS
VS = 3.0 V (@ TA = 25C, VIN = 1 V p-p, RL = 150 , unless otherwise noted).
10 CHARGE PUMP ON 0 50 60
NORMALIZED GAIN (dB)
-10
GROUP DELAY (ns)
-20 -30 -40 -50 -60 -70 CHARGE PUMP OFF
40
30
CHARGE PUMP OFF
20
10 CHARGE PUMP ON
06734-005
0.1
1 FREQUENCY (MHz)
10
100
1 FREQUENCY (MHz)
10
100
Figure 5. Large Signal Frequency Response
1 CHARGE PUMP ON 0 0 -5 -10 -15
Figure 8. Group Delay vs. Frequency
VIN = 100mV p-p DIS = 3V CHARGE PUMP ON
NORMALIZED GAIN (dB)
-1
PSRR (dB)
-20 -25 -30 -35 -40 -45
CHARGE PUMP OFF
-2 CHARGE PUMP OFF -3
-4
1 FREQUENCY (MHz)
10
1
10 FREQUENCY (MHz)
100
Figure 6. Frequency Response Flatness
-60 DIS = 0V -65 -70 0 10
Figure 9. PSRR vs. Frequency
+85C +25C 0C -40C
NORMALIZED GAIN (dB)
NORMALIZED GAIN (dB)
-10 -20 -30 -40 -50 -60 0.1
-75 -80 -85 -90 -95 -100
06734-007
1 FREQUENCY (MHz)
10
100
1 FREQUENCY (MHz)
10
100
Figure 7. Input-to-Output Isolation vs. Frequency
Figure 10. Frequency Response for Various Temperatures
Rev. 0 | Page 7 of 12
06734-010
-105 0.1
06734-009
06734-006
-5 0.1
-50 0.1
06734-008
0 0.1
ADA4431-1
1 0 -1 -2 -3 -4 -5 -6
06734-015 06734-017 06734-016
T
+85C +25C 0C -40C
NORMALIZED GAIN (dB)
2
1 FREQUENCY (MHz)
10
06734-011
-7 0.1
CH2 200mV
M100ns
A CH1
316mV
Figure 11. Flatness Response for Various Temperatures
6
Figure 14. Transient Response
T
5
SUPPLY CURRENT (mA)
4
DISABLE (DIS) PIN
1
3
2
OUTPUT
2
1
0
0.5
1.0
1.5
2.0
2.5
3.0
DISABLE (DIS) PIN VOLTAGE (V)
06734-012
0
CH1 2.00V
CH2 500mV
M10.0ms
A CH1
1.72V
Figure 12. Supply Current vs. Disable (DIS) Pin Voltage
7 6 70 60 ACTIVE 50 40 30 20 10 0 90
Figure 15. Output Enable
T
DISABLED SUPPLY CURRENT (A)
SUPPLY CURRENT (mA)
5 4 3 2 1 0 -40 -30 -20 -10
DISABLE (DIS) PIN
1
OUTPUT
2
DISABLED
0
10
20
30
40
50
60
70
80
TEMPERATURE (C)
Figure 13. Supply Current vs. Temperature
06734-014
CH1 2.00V
CH2 500mV
M40.0ns
A CH1
1.72V
Figure 16. Output Disable
Rev. 0 | Page 8 of 12
ADA4431-1 THEORY OF OPERATION
OVERVIEW
The ADA4431-1 is designed for exceptional performance as both a filter and a low power driver for portable video applications. This performance is achieved by providing third-order filtering without trading off power consumption or device size. While consuming only 4.7 mA quiescent supply current, the ADA4431-1 provides video output on a single-supply as low as 2.5 V. The ADA4431-1 also features a load detect circuit, which senses current through the external 75 back-termination resistor. When either no video load or a short circuit is detected, the ADA4431-1 enters a low power state. In this state, it draws 0.1 mA, continues to monitor the load current, and powers up automatically when a video load is connected. Optionally, the ADA4431-1 can be powered down via the disable pin (DIS). Another external pin (LDO) outputs the load detection state (for example, to an external system controller). This pin is high (+VS) when a video load is present, and low (0 V) in the absence of a video load or when the output is short-circuited. The ADA4431-1 is intended for use in applications that have both ac- and dc-coupled inputs and outputs. The rail-to-rail buffer on the ADA4431-1 output is able to drive 2 V p-p video signals into two doubly terminated video loads (150 each) on a single 2.5 V supply. The ADA4431-1 has a gain of 2 when the SAG correction pin is tied directly to the output, which makes up for the 6 dB termination loss (see Figure 17, Output Option 1). When the SAG feature is used, the ADA4431-1 has a low frequency gain of 2.5 (8 dB) and a high frequency gain of 2 (see Figure 17, Output Option 2). Signal offsets and supply levels must be considered when using the SAG correction feature to ensure that there are no headroom issues. The input range of the ADA4431-1 includes ground, while the output range is limited by the saturation of the output devices. Saturation occurs several tens of mV from the positive and negative supply rails. The high input impedance and low input capacitance of the ADA4431-1 offer advantages in a number of low power applications. In reconstruction filter applications, the DAC can be placed in its lowest power mode, allowing the use of a largevalued load resistor. Using a large-valued load resistor does not interfere with the frequency response of the ADA4431-1.
CHARGE PUMP OPERATION
The on-board charge pump creates a virtual negative supply for the output driver, which allows the output signal to be dc-coupled, with its black level at 0 V and sync tip at -300 mV. The charge pump is enabled whenever the disable pin (DIS) is held high. If DIS is left floating, or placed in a high impedance state, the ADA4431-1 is powered up, but the charge pump is disabled, which is typically the case for ac-coupling of the output. When DIS is driven to 0 V, the entire device is powered down. Table 6. Disable (DIS) Pin Function Summary
DIS Pin Low High High-Z Device State Disabled Enabled Enabled Charge Pump State Disabled Enabled Disabled
LOAD DETECT
The load detect feature provides additional system power management to keep the power consumption of a portable device to the absolute minimum. The ADA4431-1 monitors the output load for three conditions: a normal load, a shorted load, and an open load. Each of these conditions occurs for a video load, an audio load, and no load, respectively. Only in the video load condition will the ADA4431-1 power up from 0.1 mA to 4.7 mA. A single I/O pin, LDO, notifies the system by either being high for a video load or low for a short and open load. With this information, it is intended that the system controller power down any power intensive video processing blocks to realize substantial power savings. The ADA4431-1 operates autonomously, requiring no inputs to monitor the condition of the output load.
Rev. 0 | Page 9 of 12
ADA4431-1 EVALUATION BOARD
The ADA4431-1 evaluation board allows designers to assess the performance of the part in their particular application. The board includes input and output SMA coaxial connectors and 75 -controlled impedance signal traces. Power (2.5 V to 3.6 V) is applied to the red V+ loop connector, and ground is connected to the black GND loop connector. The output signal can be configured for dc coupling or ac coupling. When ac-coupled, two options are available: the standard single capacitor configuration (minimum of 220 F) and the SAG-corrected configuration, using two smaller capacitors (47 F and 22 F). Jumper Block J2 allows the load detect feature to be evaluated without connecting an external video load. Connecting a jumper from the center pin to the 75 position applies a 75 load to the output and causes the LDO pin to go high. Connecting the center pin to the GND position short circuits the output, causing the ADA4431-1 to power down, and the LDO pin to go low. If an external video load is connected to the OUT connector, the jumper should be removed. With the jumper removed, disconnecting the external load also causes the ADA4431-1 to power down. Jumper Block J4 exercises the disable pin (DIS). When a jumper is connected from the center pin to V+, the charge pump is enabled. Connecting the center pin to GND forces the ADA4431-1 into low power mode. With the jumper removed, the ADA4431-1 is enabled but the charge pump is disabled. A schematic of the ADA4431-1 evaluation board, with output coupling options, is shown in Figure 17. Figure 18 and Figure 19 show the front and back layout of the evaluation board.
R6 75 J2
OUTPUT OPTION 1
C5 0 C4 0 C6 220F
+
75 OUT R5 75 C5 0 V+ C4 0 C6 0 GND
14
AC-COUPLED 13 OUTPUT
LD2 GND
C9 0.1F R1 0 R2 75 R4 DNI 1 +VS 2 IN 3 DIS
16 15
FB1 FB2
14
OUT
DC-COUPLED 13 OUTPUT
SAG
GND 12 C3 1.0F SUBS V+
IN
SUBS 11
ADA4431-1
CAP4 CAP3 CAP2 GND
+VS
10 C7 0.1F
4 LDO DIS R3 DNI J4 GND DIS V+ C8 + 10F V+
CAP1 9
OUTPUT OPTION 2
C5 47F C2 0.1F
+
5
LDOUT C1 0.1F LDO
6
7
8
C6 0
14
13
C4 22F
Figure 17. Evaluation Board Schematic
Rev. 0 | Page 10 of 12
06734-018
AC-COUPLED OUTPUT WITH SAG CORRECTION
+
ADA4431-1
06743-019
Figure 18. Evaluation Board--Front
Figure 19. Evaluation Board--Back
Rev. 0 | Page 11 of 12
06743-020
ADA4431-1 OUTLINE DIMENSIONS
INDEX AREA 3.00 BSC SQ
13 12 16 EXPOSED PAD 9 4
PIN 1 INDICATOR
1
1.80 1.70 SQ 1.55
5
0.50 BSC TOP VIEW 0.60 0.55 0.51 SEATING PLANE 0.30 0.25 0.18 0.05 MAX 0.02 NOM 0.08 REF
8
BOTTOM VIEW
0.40 MAX 0.30 NOM
COMPLIANT TO JEDEC STANDARDS MO-248-UEED.
Figure 20. 16-Lead Lead Frame Chip Scale Package [LFCSP_UQ] 3 mm x 3 mm Body, Ultra Thin Quad (CP-16-12) Dimensions shown in millimeters
ORDERING GUIDE
Model ADA4431-1YCPZ-R2 1 ADA4431-1YCPZ-R71 ADA4431-1YCPZ-RL1
1
Temperature Range -40C to +85C -40C to +85C -40C to +85C
Package Description 16-Lead LFCSP_UQ 16-Lead LFCSP_UQ 16-Lead LFCSP_UQ
Package Option CP-16-12 CP-16-12 CP-16-12
Branding H12 H12 H12
053106-B
Ordering Quantity 250 3,000 10,000
Z = RoHS Compliant Part.
(c)2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06734-0-8/07(0)
T T
Rev. 0 | Page 12 of 12

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