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PDF ADA4430-1 Data sheet ( Hoja de datos )
| Número de pieza | ADA4430-1 | |
| Descripción | Ultralow Power Video Filter | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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FEATURES
6th-order performance, low-pass video filter
1 dB flatness out to 8 MHz
50 dB rejection at 27 MHz
Ultralow power-down current: 0.1 μA typ
Low quiescent current: 1.85 mA typ
Excellent video specification
Differential gain: 0.25%
Differential phase: 0.10°
SAG correction
Allows use of small capacitors in ac-coupled outputs
Low supply voltage: 2.5 V to 6 V
Rail-to-rail output
High input-to-output isolation in disabled state
92 dB @ 1 MHz
Low input bias current: 0.5 μA
Small packaging: SC70
Wide operating temperature range: −40°C to +125°C
APPLICATIONS
Portable media players
Portable gaming consoles
Cell phones
Digital still cameras
Portable DVD players
Portable video cameras
GENERAL DESCRIPTION
The ADA4430-1 is a fully integrated video reconstruction filter
that combines excellent video specifications with low power
consumption and an ultralow power disable, making it ideal
for portable video filtering applications. With 1 dB frequency
flatness out to 8 MHz and 50 dB rejection at 27 MHz, the
ADA4430-1 is ideal in SD video applications, including
NTSC and PAL.
The ADA4430-1 operates on single supplies as low as 2.5 V and
as high as 6 V while providing the dynamic range required by
the most demanding video systems.
Ultralow Power Video Filter
with Power-Down
ADA4430-1
PIN CONFIGURATION
VIN 1
ADA4430-1
x1 6 VS+
GND 2
2*R
SAG 3
2*R
R
2*R
Figure 1.
5 PD
4 VOUT
6.5
6.0 VS = 3V
VS = 5V
5.5
5.0
4.5
4.0
3.5
3.0
1
FREQUENCY (MHz)
10
Figure 2. Frequency Response Flatness at Various Power Supplies
The ADA4430-1 also provides an on-chip dc offset to avoid
clipping of the sync tips at the filter output, as well as SAG
correction that permits smaller capacitor values to be used in
applications with ac-coupled outputs.
The ADA4430-1 is available in a 6-lead SC70 package and is
rated to work in the extended automotive temperature range of
−40°C to +125°C.
Rev. A
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.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
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
©2006 Analog Devices, Inc. All rights reserved.
1 page  
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Table 5. Pin Function Descriptions
Pin Number
Mnemonic
1 VIN
2 GND
3 SAG
4 VOUT
5 PD
6 VS+
VIN 1
ADA4430-1
x1 6 VS+
GND 2
2*R
SAG 3
2*R
R
2*R
5 PD
4 VOUT
Figure 4. 6-Lead SC70, Top View
Description
Input Voltage.
Ground.
Feedback Connection.
Output Voltage.
Power Down.
Positive Power Supply.
ADA4430-1
Rev. A | Page 5 of 16
5 Page 
THEORY OF OPERATION
OVERVIEW
The ADA4430-1 is designed for exceptional performance as
both a filter and a low power driver for portable video
applications. This performance is achieved by providing high
order filtering without trading off power consumption or device
size. While consuming only 1.85 mA quiescent supply current,
the ADA4430-1 provides video output on a single-supply as low
as 2.5 V. Such low power consumption and low supply operation
would normally indicate a single op amp with a 2- or 3-pole
roll-off; however, the ADA4430-1 achieves a sixth-order roll-off
in addition to a 10 MΩ input impedance for easy clamping and
lower DAC output power requirements. When not in use, the
ADA44330-1 can be shutdown to draw less than 1 μA of supply
current using the power-down pin, (PD). Additionally, the
ADA4430-1 is unique in that it is a high order filter that fits into
an SC70 package.
The ADA4430-1 provides a minimum 1 dB bandwidth of
5.5 MHz and a minimum stop-band rejection of 42 dB at
27 MHz. Phase response is not sacrificed in spite of the
exceptional filtering performance of the ADA4430-1, as
exhibited by its group delay, which varies by only 7 ns from
100 kHz to 5 MHz.
The ADA4430-1 is intended for use in applications that have
both ac- and dc-coupled inputs and outputs. The rail-to-rail
buffer on the ADA4430-1 output is able to drive 2 V p-p video
signals into two doubly-terminated video loads (150 Ω each) on
a single 2.5 V supply. The ADA4430-1 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. When the SAG feature is used
(see Figure 29), the ADA4430-1 has a low frequency gain of
2.5 (≈ 8 dB) and a high frequency gain of 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 ADA4430-1 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. For accurate reproduction of ground-
referenced input signals, an internal offset is used to shift the
output up by 95 mV.
The high input impedance and low input capacitance of the
ADA4430-1 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 large-
valued load resistor. Using a large-valued load resistor does not
interfere with the frequency response of the ADA4430-1.
ADA4430-1
The internal buffer at the ADA4430-1 input isolates the source
resistance feeding the ADA4430-1 from the internal filter networks.
High input impedance is also advantageous when using video
clamping circuits.
The output buffer feedback network used to create a gain of 2 is
connected internally to the GND pin and has a nominal impedance
of 5.2 kΩ. The current required to drive this feedback network
causes the overall supply current to vary based on the output
level. The feedback impedance was chosen specifically to
minimize excess current consumption while maintaining
optimal frequency behavior.
POWER SAVINGS USING THE ADA4430-1
Using a series source termination and a shunt load termination
on a low supply voltage with the ADA4430-1 realizes significant
power savings compared with driving a video cable directly from
a DAC output. Figure 27 shows a video DAC driving a cable
directly. Properly terminating the line results in the DAC driving
two 75 Ω loads and requires in excess of 30 mA to reach a full-
scale level of 1.3 V. Figure 28 shows the same video load being
driven using the ADA4430-1 and a series-shunt termination. This
requires two times the output voltage to drive the equivalent of
150 Ω but only requires a little more than 15 mA to reach a full-
scale output. When running on the same supply voltage as the
DAC, this results in nearly a factor of two reduction in power
compared with the circuit in Figure 27. The high level of
filtering provided by the ADA4430-1 lowers the requirements
on the DAC oversampling ratio, realizing further power savings.
On any given DAC, 8× and 16× oversampling ratios can require
twice the power consumption of a 4× oversampling ratio.
3V
VIDEO
DAC/
ENCODER
75Ω
75Ω
Figure 27. DAC Driving Video Cable Directly
3V
0.1µF
VIDEO
DAC/
ENCODER
ADA4430-1
FILTER
RL G = +2
75Ω
75Ω
Figure 28. DAC Driving Video Cable Using the ADA4430-1
Rev. A | Page 11 of 16
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet ADA4430-1.PDF ] | |
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