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PDF ADA4800 Data sheet ( Hoja de datos )
| Número de pieza | ADA4800 | |
| Descripción | High Speed CCD Buffer Amplifier | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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FEATURES
Integrated active load and gain of 1 buffer
Very low buffer power consumption
As low as 20 mW on chip
Power save feature to reduce active load current by GPO
control
High buffer speed
400 MHz, −3 dB bandwidth
415 V/μs slew rate
Fast settling time to 1%, 2 V step: 5 ns
Adjustable buffer bandwidth
Push-pull output stage
Adjustable active load current
Small package: 1.6 mm × 1.6 mm × 0.55 mm
APPLICATIONS
CCD image sensor output buffer
Digital still cameras
Camcorders
GENERAL DESCRIPTION
The ADA4800 is voltage buffer integrated with an active load.
The buffer is a low power, high speed, low noise, high slew rate,
fast settling, fixed gain of 1 monolithic amplifier for charge-
coupled device (CCD) applications. For CCD applications, the
active load current source (IAL) can load the open source CCD
sensor outputs and the buffer can drive the AFE load. The active
current load can also be switched off, to use the ADA4800 as just
a unity gain buffer. The buffer consumes only 20 mW of static
power. In applications where power savings is critical, the
ADA4800 features a power save mode (see the Power Save
Mode section), which further reduces the total current
consumption. The bandwidth of the ADA4800 buffer is also
fully adjustable through the IDRV pin.
The buffer of the ADA4800 employs a push-pull output stage
architecture, providing drive current and maximum slew
capability for both rising and falling signal transitions. At a
5 mA quiescent current setting, it provides 400 MHz, −3 dB
bandwidth, which makes this buffer well suited for CCD
sensors from machine vision to digital still camera applications.
The ADA4800 is ideal for driving the input of the Analog
Devices, Inc., 12-bit and 14-bit high resolution analog
front ends (AFE) such as the AD9928, AD9990, AD9920A,
AD9923A, and AD997x family.
Low Power, High Speedwww.DataSheet4U.com
CCD Buffer Amplifier
ADA4800
FUNCTIONAL BLOCK DIAGRAM
IN 1
VEE 2
ADA4800
6 ISF
IISF
IAL IBUFF
ICC
+1 5 VCC
OUT 3
IIDRV
4 IDRV
Figure 1.
The versatility of the ADA4800 allows for seamless interfacing
with many CCD sensors from various manufacturers.
The ADA4800 is designed to operate at supply voltages as low
as 4 V and up to 17 V. It is available in a 1.6 mm × 1.6 mm ×
0.55 mm, 6-lead LFCSP package and is rated to operate over the
industrial temperature range of −40oC to +85oC.
VISF
3V
RISF
10kΩ
0.1µF +10µF
RIDRV
249kΩ
15V
ISF
6
IISF
VCC
5
IIDRV
IDRV
4
IBUFF
+1
ADA4800
1
IN
IAL
49.9Ω
7.5V
2
VEE
10Ω
22pF
3
OUT
1kΩ
7.5V
Figure 2. Typical Test Circuit
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
©2010 Analog Devices, Inc. All rights reserved.
1 page  
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
ADA4800
IN 1
6 ISF
VEE 2
EPAD
5 VCC
OUT 3
4 IDRV
NOTES
1. EXPOSED PAD IS NOT INTERNALLY
CONNECTED TO DIE. CONNECT TO ANY LOW
IMPEDANCE NODE OR LEAVE FLOATING.
Figure 3. Pin Configuration
ADA4800www.DataSheet4U.com
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
1 IN Input. Connect this pin to the CCD sensor output.
2 VEE Negative Power Supply Voltage.
3 OUT Output. Connect this pin to the AFE input.
4
IDRV
Bandwidth Adjustment Pin. Connect this pin to VCC or an external voltage with an external resistor. This pin
allows bandwidth to be controlled by adjusting ICC. This pin can also be used to power down the buffer.
5 VCC Positive Power Supply Voltage.
6 ISF Active Load Current Adjustment Pin. Connect to VCC or an external voltage with an external resistor. This pin can
also be connected to the microcontroller logic output through an external resistor for power save mode. This pin
can also be used to power down the active current load.
EPAD
EPAD
Exposed Pad. Not internally connected to die. Connect to any low impedance node or leave floating.
Rev. A | Page 5 of 16
5 Page 
ADA4800www.DataSheet4U.com
APPLICATIONS INFORMATION
OPEN SOURCE CCD OUTPUT BUFFER
With low power, high slew rate, and fast settling time, the
ADA4800 is the ideal solution for an output buffer for CCD
sensors with an open source output configuration. Figure 21
shows a typical application circuit for the ADA4800 as a CCD
sensor output buffer.
The output of the CCD is connected directly to the IN pin
of the ADA4800, whose OUT pin is then ac-coupled into
the input of the analog front end.
15V
0.1µF
VISF
RISF
120kΩ
ISF
6
IISF
+
0.1µF 47µF
0.1µF
VCC
5
IIDRV
RIDRV
249kΩ
IDRV
4
IBUFF
+1
ADA4800
15V
CCD
1
IN
IAL
2
VEE
3
OUT
AFE
Figure 21. Typical Application Block Diagram
To help reduce the effects of power supply noise coupling into
the ISF and IDRV pins, use 0.1 μF ceramic bypass decoupling
capacitors. For best performance, place these capacitors as
close to each of these pins as is physically possible.
POWER SAVE MODE
The buffer of the ADA4800 consumes only 20 mW of static
power. To achieve even more power savings, the ADA4800
active load current can be switched off during standby mode
or reduced during monitoring mode. Figure 22 illustrates the
ADA4800 as an open source CCD buffer configured for using
this power save feature. Power save mode allows IAL current to
be logically controlled by connecting the ISF pin to any general-
purpose output (GPO) pin of the system microcontroller through
an external resistor. A GPO logic high enables the flow of input
sink current, while a logic low disables the input sink current
and asserts the power save mode.
0V TO 3V
GPO PIN
VISF
0.1µF
RISF
10kΩ
ISF
6
IISF
+
0.1µF 47µF
0.1µF
VCC
5
IIDRV
RIDRV
249kΩ
IDRV
4
IBUFF
+1
ADA4800
15V
CCD
1
IN
IAL
2
VEE
3
OUT
AFE
Figure 22. Using GPO to Drive ISF Voltage
Figure 23 shows an example of the ADA4800 power save feature.
GPO1
AFE
GPO2
20kΩ
20kΩ
ISF ADA4800
MAIN BOARD FPC
Figure 23. Example Block Diagram for Sink Current Selection
Three combinations of IAL are provided with Figure 23.
Selection of the IAL is controlled by the logic signals applied to
the GPO1 and GPO2 pins. Table 5 summarizes the IAL selections.
Table 5. Input Sink Current Selection
Mode
GPO1
Standby
High-Z
0
Sleep
High-Z
1
Active
1
GPO2
High-Z
0
1
High-Z
1
Resistance (kΩ)
High-Z
N/A
20
20
10
Active Load Current, IAL (mA)
0
1.90
3.36
Rev. A | Page 11 of 16
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet ADA4800.PDF ] | |
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