Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com
xrxr XRD87L99
LOW POWER, 2 MSPS, 10-BIT, A/D CONVERTER WITH 8-CHANNEL MUX
FEBRUARY 2001 REV. 1.0.0
FEATURES
• 10-Bit Resolution
• 8-Channel Mux
• Sampling Rate - < 1kHz - 2MHz
• Low Power CMOS - 24 mW (typ)
• Power Down; Lower Consumption - 0.1 mW (typ)
• Input Range between GND and V
DD
• No S/H Required for Analog Signals less than
100kHz
• No S/H Required for CCD Signals less than 2MHz
• Single Power Supply (2.7 to 3.6V)
• Latch-Up Free
• ESD Protection: 2000 Volts Minimum
APPLICATIONS
•
µP/DSP Interface and Control Application
• High Resolution Imaging - Scanners & Copiers
• Wireless Digital Communications
• Multiplexed Data Acquisition
BENEFITS
• Reduced Board Space (Small Package)
• Reduced External Parts, No Sample/Hold Needed
• Suitable for Battery & Power Critical Applications
• Designer can Adapt Input Range & Scaling
GENERAL DESCRIPTION
The XRD87L99 is a flexible, easy to use, precision
10-bit analog-to-digital converter with 8-channel mux
that operates over a wide range of input and sampling
conditions. The XRD87L99 can operate with pulsed
"on demand" conversion operation or continuous
"pipeline" operation for sampling rates up to 2MHz.
The elimination of the S/H requirements, very low
power, and small package size offer the designer a
low cost solution. No sample and hold is required for
CCD applications up to 2MHz, or multiplexed input
applications when the signal source bandwidth is lim-
ited to 100kHz. The input architecture of the
XRD87L99 allows direct interface to any analog input
range between AGND and AV
DD
. The user simply
sets V
REF(+)
and V
REF(-)
to encompass the desired in-
put range.
Scaled reference resistor taps @ 1/4 R, 1/2 R and 3/4
R allow for customizing the transfer curve as well as
providing a 1/2 span reference voltage. Digital out-
puts are CMOS and TTL compatible.
The XRD87L99 uses a two-step flash technique. The
first segment converts the 5 MSBs and consists of
autobalanced comparators, latches, an encoder, and
buffer storage registers. The second segment con-
verts the remaining 5 LSBs.
When the power down input is "high", the data out-
puts DB9 to DB0 hold the current values and V
REF(-)
is
disconnected from V
REF1(-)
. The power consumption
during the power down mode is 0.1mW.
ORDERING INFORMATION
PART NUMBER PACKAGE OPERATING TEMPERATURE RANGE
XRD87L99AIQ PQFP
-40
°
C to +85
°
C
