and Sample/Hold. ADC10662 Datasheet
10-Bit 360 ns A/D Converter with Input Multiplexer and
Using an innovative, patented multistep* conversion tech-
nique, the 10-bit ADC10662 and ADC10664 are 2- and
4-input CMOS analog-to-digital converters offering
sub-microsecond conversion times yet dissipating a maxi-
mum of only 235 mW. The ADC10662 and ADC10664 per-
form a 10-bit conversion in two lower-resolution “flashes”,
thus yielding a fast A/D without the cost, power dissipation,
and other problems associated with true flash approaches.
In addition to standard static performance specifications
(Linearity, Full-Scale Error, etc.) dynamic performance (THD,
S/N) is guaranteed.
The analog input voltage to the ADC10662 and ADC10664 is
sampled and held by an internal sampling circuit. Input sig-
nals at frequencies from dc to over 250 kHz can therefore be
digitized accurately without the need for an external
The ADC10662 and ADC10664 include a “speed-up” pin.
Connecting an external resistor between this pin and ground
reduces the typical conversion time to as little as 360 ns.
For ease of interface to microprocessors, the ADC10662 and
ADC10664 have been designed to appear as a memory lo-
cation or I/O port without the need for external interface
n Built-in sample-and-hold
n Single +5V supply
n 2- or 4-input multiplexer options
n No external clock required
n Conversion time to 10 bits: 360 ns typical, 466 ns
max over temperature
n Sampling Rate: 1.5 MHz (min)
n Low power dissipation: 235 mW (max)
n Total harmonic distortion (50 kHz): −60 dB (max)
n No missing codes over temperature
n Digital signal processor front ends
n Disk drives
n Mobile telecommunications
(−40˚C ≤ TA ≤ +85˚C)
M24B Small Outline
(−40˚C ≤ TA ≤ +85˚C)
M28B Small Outline
*U.S. Patent Number 4918449
TRI-STATE® is a registered trademark of National Semiconductor Corporation.
© 1999 National Semiconductor Corporation DS011192
Simplified Block Diagram
These are the digital and analog positive sup-
ply voltage inputs. They should always be con-
nected to the same voltage source, but are
brought out separately to allow for separate
bypass capacitors. Each supply pin should be
bypassed with a 0.1 µF ceramic capacitor in
parallel with a 10 µF tantalum capacitor to
This is the active low interrupt output. INT
goes low at the end of each conversion, and
returns to a high state following the rising edge
of RD .
This is the Sample/Hold control input. When
this pin is forced low (and CS is low), it causes
the analog input signal to be sampled and ini-
tiates a new conversion.
This is the active low Read control input.
When this RD and CS are low, any data
present in the output registers will be placed
on the data bus.
This is the active low Chip Select control input.
When low, this pin enables the RD and S /H
These pins select the analog input that will be
connected to the A/D during the conversion.
The input is selected based on the state of S0
and S1 when S /H makes its High-to-Low tran-
sition (See the Timing Diagrams). The
ADC10664 includes both S0 and S1. The
ADC10662 includes just S0.
These are the reference voltage inputs. They
may be placed at any voltage between GND
and VCC, but VREF+ must be greater than
VREF−. An input voltage equal to VREF− pro-
duces an output code of 0, and an input volt-
age equal to (VREF+ − 1 LSB) produces an out-
put code of 1023.
These are the analog input pins. The
ADC10662 has two inputs (VIN0 and VIN1) and
the ADC10664 has four inputs (VIN0, VIN1,
VIN2 and VIN3). The impedance of the source
should be less than 500Ω for best accuracy
and conversion speed. For accurate conver-
sions, no input pin (even one that is not se-
lected) should be driven more than 50 mV
above VCC or 50 mV below ground.
GND, AGND, These are the power supply ground pins. The
ADC10662 and ADC10664 have separate
analog and digital ground pins (AGND and
DGND) for separate bypassing of the analog
and digital supplies. The ground pins should
be connected to a stable, noise-free system
ground. Both pins should be returned to the
DB0–DB9 These are the TRI-STATE output pins.
By connecting a resistor between this pin and
ground, the conversion time can be reduced.
The specifications listed in the table of Electri-
cal Characteristics apply for a speed adjust re-
sistor (RSA) equal to 14.0 kΩ (Mode 1) or 8.26
kΩ (Mode 2). See the Typical Performance
Curves and the table of Electrical Characteris-