Operating Temperature Range *
0°C to +70°C0°C to +70°C
18-Pin 18-Pin
Plastic Pin Small Outline
Package Package (SOIC)
ALD521DPD ALD521DSD
* Contact factory for industrial temperature range
FEATURES AND BENEFITS
• Low cost, simple functionality
• PC parallel printer port interface standard
• Support resolution up to 23 binary bits + sign
polarity bit
• Easy to use to acquire up to 23 bit linearity
and noise performance
• Integration time can be set by the user
• Easy user evaluation and setting of
conversion parameters
• Low power dissipation - 4 mA typical
including crystal oscillator
• On-chip Crystal Oscillator Circuit
• Two way asynchronous handshake data
transfer
• Conversion speed versus resolution trade-off
• Power down (sleep mode) control input to
power down to 2 µA
• Chip Select control input
• High impedance DV, DOUT and SCLK
when chip not selected
• Single 3 V to 5 V power supply
ALD521D
ADVANCED
LINEAR
DEVICES, INC.
ORDERING INFORMATION
24 BIT SERIAL INTERFACE DIGITAL CONTROLLER
APPLICATIONS
• Operate in conjunction with ALD500/ALD500R
Precision analog signal processors
• High accuracy DC voltage measurement functions
• Portable battery operated instruments
• PC-based software control or stand-alone operation (without
other processors or PC)
• Serial digital output interface to other microprocessors or
microcontrollers
GENERAL DESCRIPTION
The ALD521D is a digital controller designed to interface to the ALD500
or ALD500R integrating dual slope analog processors as a chip set for
building a precision analog-to-digital converter. With the ALD521D and
ALD500R, together with a few external capacitors and resistors, a
precision Analog to Digital converter with auto zero and auto-polarity
can be implemented.
The ALD521D can operate in either a stand-alone mode or in an
external microprocessor control mode. In the stand-alone mode, the
ALD521D can either making continuous measurements or a single
measurement. Under external microprocessor control, the ALD521D
can directly interact with a PC under PC software control via a standard
parallel printer port with no other components, or it can also communicate
with other microcontrollers serially.
The ALD500/ALD500R analog processors consist of on-chip digital
control circuitry to accept control inputs, integrating buffer amplifiers,
analog switches, and voltage comparators. It functions in four operating
modes, or phases, namely auto zero, integrate, deintegrate, and
integrator zero phases. At the end of a conversion, the comparator
output goes from high to low when the integrator crosses zero during
deintegration. ALD500 analog processors also provide direct logic
interface to CMOS logic families.
© 2000 Advanced Linear Devices, Inc., 415 Tasman Drive, Sunnyvale, California 94089-1706, Tel: (408) 747-1155, Fax: (408) 747-1286
http://www.aldinc.com
PIN CONFIGURATION
* Note: N/C - No Conncection
1
2
3
14
15
16
4
13
5
12
DGND
A
6
7
8
10
11
S
2
PWRUP
XTAL
OUT
9
B

DV
PD, SD PACKAGE
17
18
S
3
C
OUT
V
+
XTAL
IN
C
OUT
D
OUT
S
1
N/C
ALD521D

S
CLK
C
S
CS