19-1597; Rev 0; 1/00
10-Bit, 20Msps ADC
General Description
The MAX1425 10-bit, monolithic analog-to-digital con-
verter (ADC) is capable of a 20Msps sampling rate. This
device features an internal track-and-hold (T/H) amplifier
for excellent dynamic performance; at the same time, it
minimizes the number of external components. Low
input capacitance of only 8pF minimizes input drive
requirements. A wide input bandwidth (up to 150MHz)
makes this device suitable for digital RF/IF downconvert-
er applications employing undersampling techniques.
The MAX1425 employs a differential pipelined architec-
ture with a wideband T/H amplifier to maximize through-
put while limiting power consumption to only 172mW.
The MAX1425 generates an internal +2.5V reference
that supplies three additional reference voltages
(+3.25V, +2.25V, and +1.25V). These reference volt-
ages provide a differential input range of +2V to -2V.
The analog inputs are biased internally to correct the
DC level, eliminating the need for external biasing on
AC-coupled applications.
A separate +3V digital logic supply input allows for
separation of digital and analog circuitry. The output
data is in two’s complement format. The MAX1425 is
available in the space-saving 28-pin SSOP package.
For a pin-compatible version at a lower data rate, refer
to the MAX1426 data sheet. For a higher data rate, refer
to the MAX1424 data sheet.
Features
o
Differential Inputs for High Common-Mode
Noise Rejection
o
Signal-to-Noise Ratio
61dB (at f
IN
= 2MHz)
59.3dB (at f
IN
= 10MHz)
o
Internal +2.5V Reference
o
150MHz Input Bandwidth
o
Wide ±2V Input Range
o
Low Power Consumption: 172mW
o
Separate Digital Supply Input for 3V Logic
Compatibility
o
Single +5V Supply Operation Possible
MAX1425
Ordering Information
PART
MAX1425CAI
MAX1425EAI
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
28 SSOP
28 SSOP
Applications
Medical Ultrasound Imaging
CCD Pixel Processing
IR Focal Plane Array
Radar
IF and Baseband Digitization
Set-Top Boxes
TOP VIEW
AGND 1
AV
DD
2
REFP 3
REFIN 4
REFN 5
Pin Configuration
28 D0
27 D1
26 D2
25 D3
24 D4
Functional Diagram
CLK
INTERFACE
INP
T/H
INN
REF SYSTEM +
BIAS
PIPELINE ADC
MAX1425
AV
DD
AGND
CML 6
AGND 7
AV
DD
8
INP 9
INN 10
MAX1425
23 DGND
22 DV
DD
21 DGND
20 DV
DD
19 D5
18 D6
17 D7
16 D8
15 D9
OUTPUT
DRIVERS
D9–D0
DV
DD
DGND
CMLP 11
CMLN 12
CLK 13
OE/PD 14
REF
REFIN REFP
CML REFN
OE/PD
SSOP
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
