Low Power, High Speed
CCD Buffer Amplifier
ADA4800
Rev. A
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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
FUNCTIONAL BLOCK DIAGRAM
09162-001
6
ISF
1
IN
5
VCC
I
AL
I
BUFF
I
CC
2
VEE
4
IDRV
3
UT
ADA4800
+1
I
IDRV
I
ISF
Figure 1.
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 (I
AL
) 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.
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 −40
o
C to +85
o
C.
09162-102
6
ISF
1
IN
5
VCC
2
VEE
4
IDRV
3
OUT
ADA4800
R
ISF
10kΩ
3V
7.5V
ISF
R
IDRV
249kΩ
15V
0.1µF
+
10µF
49.9Ω
7.5V
1kΩ10Ω
22pF
I
AL
I
BUFF
+1
I
IDRV
I
ISF
Figure 2. Typical Test Circuit
