8-Bit 20 MSPS, 60 mW
Sampling A/D Converter
a
AD775
FUNCTIO NAL BLO CK D IAGRAM
FEATURES
V
AV
IN
CMOS 8-Bit 20 MSPS Sam pling A/ D Converter
Low Pow er Dissipation: 60 m W
+5 V Single Supply Operation
Differential Nonlinearity: 0.3 LSB
Differential Gain: 1%
DD
DV
DD
19
18 14 15
11
13
AV
DD
AD775
10
D7 (MSB)
9
8
7
15
4
16
17
COARSE
COMPARATORS
V
RTS
Differential Phase: 0.5 Degrees
Three-State Outputs
V
RT
8
6
5
FINE COMPARATORS
On-Chip Reference Bias Resistors
Adjustable Reference Input
Video Industry Standard Pinout
Sm all Packages:
24-Pin 300 Mil SOIC Surface Mount
24-Pin 400 Mil Plastic DIP
BANK A
5
4
3
255
23
22
V
FINE COMPARATORS
BANK B
RB
D0 (LSB)
OE
V
RBS
1
CLOCK LOGIC
AV
SS
2
24
20
AV
21
SS
12
CLK
DV
SS
P RO D UCT H IGH LIGH TS
P RO D UCT D ESCRIP TIO N
Low Power: T he AD775 has a typical supply current of 12 mA,
for a power consumption of 60 mW. Reference ladder current
is also low: 6.6 mA typical, minimizing the reference power
consumption.
T he AD775 is a CMOS, low power, 8-bit, 20 MSPS sampling
analog-to-digital converter (ADC). T he AD775 features a built-
in sampling function and on-chip reference bias resistors to pro-
vide a complete 8-bit ADC solution. T he AD775 utilizes a
pipelined/ping pong two-step flash architecture to provide high
sampling rates (up to 35 MH z) while maintaining very low
power consumption (60 mW).
Complete Solution: T he AD775’s switched capacitor design
features an inherent sample/hold function: no external SHA is
required. On-chip reference bias resistors are included to allow
a supply-based reference to be generated without any external
resistors.
Its combination of excellent DNL, fast sampling rate, low dif-
ferential gain and phase errors, extremely low power dissipation,
and single +5 V supply operation make it ideally suited for a
variety of video and image acquisition applications, including
portable equipment. T he AD775’s reference ladder may be con-
nected in a variety of configurations to accommodate different
input ranges. The low input capacitance (11 pF typical) provides
an easy-to-drive input load compared to conventional flash
converters.
Excellent Differential Nonlinearity: T he AD775 features a
typical DNL of 0.3 LSBs, with a maximum limit of 0.5 LSBs.
No missing codes is guaranteed.
Single +5 V Supply Operation: T he AD775 is designed to oper-
ate on a single +5 V supply, and the reference ladder may be
configured to accommodate analog inputs inclusive of ground.
Low Input Capacitance: T he 11 pF input capacitance of the
AD775 can significantly decrease the cost and complexity of
input driving circuitry, compared with conventional 8-bit flash
ADCs.
T he AD775 is offered in both 300 mil SOIC and 400 mil DIP
plastic packages, and is designed to operate over an extended
commercial temperature range (–20°C to +75°C).
REV. 0
Inform ation furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assum ed by Analog Devices for its
use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
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Tel: 617/ 329-4700
Fax: 617/ 326-8703