CMOS 8-Bit High Speed
Analog-to-Digital Converter
April 2002
XRD8785
FEATURES
• 8-Bit Resolution
• Up to 20 MHz Sampling Rate
• Internal S/H Function
• Single Supply: 5V
• VIN DC Range: 0V to V
DD
• VREF DC Range: 1V to V
DD
• Low Power: 75mW typ. (excluding reference)
• Latch-Up Free
• ESD Protection: 2000V Minimum
• 20-Pin Package Available: XRD8775
• 3V Version: XRD87L85
APPLICATIONS
• Digital Color Copiers
• Cellular Telephones
• CCDs and Scanners
• Video Capture Boards
GENERAL DESCRIPTION
The XRD8785 is an 8-bit Analog-to-Digital Converter.
Designed using an advanced 5V CMOS process, this
part offers excellent performance, low power con-
sumption, and latch-up free operation.
This device uses a two-step flash architecture to
maintain low power consumption at high conversion
rates. The input circuitry of the XRD8785 includes an
on-chip S/H function which allows the user to digitize
analog input signals between AGND and AV
DD
. Careful
design and chip layout have achieved a low analog
input capacitance. This reduces “kickback” and eases
the requirements of the buffer/amplifier used to drive
the XRD8785. The designer can choose the internally
generated reference voltages by connecting V
RB
to
V
RBS
and V
RT
to V
RTS
, or provide external reference
voltages to the V
RB
and V
RT
pins. The internal reference
generates 0.6V at V
RB
and 2.6 V at V
RT
. Providing
external reference voltages allows easy interface to
any input signal range between AGND and AV
DD
. This
also allows the system to adjust these voltages to
cancel zero scale and full scale errors, or to change the
input range as needed.
The device operates from a single +5V supply. Power
consumption is 75mW at FS = 15MHz. Specified for
operation over the commercial/industrial (–40 to
+85°C) temperature range, the XRD8785 is available in
Plastic Dual-in-line (PDIP), Surface Mount (SOIC) and
Small Outline (SOP) packages in EIAJ and JEDEC.
SIMPLIFIED BLOCK AND TIMING DIAGRAM
Rev. 3.00
EXAR
Corporation, 48720 Kato Road, Fremont, CA 94538
•
(510) 668-7000
•
FAX (510) 668-7017
EXAR [ EXAR CORPORATION ]
