AS1526/AS1527
Data Sheet
- D e t a i l e d
Description
8 Detailed Description
The AS1526/AS1527 analog-to-digital converters have two modes of operation:
!
Normal A/D Conversion Mode – Pulling pin SHDNN high or leaving it open puts the device into normal A/D conver-
sion mode.
Shutdown Mode – Pulling pin SHDNN low shuts the device down and reduces supply current below 2µA (V
DD
≤
3.6V).
!
Note:
Pulling pin CSN low starts a conversion. The conversion result is available at pin DOUT in unipolar serial for-
mat
shows a basic configuration for the AS1526/AS1527. The integrated input track/hold circuitry and a succes-
sive-approximation register (SAR) circuitry convert analog input signals to a digital 10-bit output. No external-hold
capacitor is needed for the track/hold circuit.
The devices convert analog input signals in the 0V to V
REF
range in 13µs (includes track/hold acquisition time).
The AS1526 internal reference is trimmed to 2.5V; the AS1527 requires an external reference. Both devices can
accept external reference voltages from 1.0V to V
DD
. The serial interface requires only three digital lines (at pins
SCLK, CSN, and DOUT) and provides a simple microprocessor interface.
Figure 23. Operational Diagram
1
+
4.7µF
0.1µF
2
AIN
3
SHDNN
Reference Input
Required for AS1527,
Optional for AS1526
7
CSN
V
DD
8
SCLK
+2.7 to +3.6V
AS1526/
AS1527
6
DOUT
4
REF
AS1526 – 4.7µF
AS1527 – 0.1µF
5
GND
Analog Input
illustrates the integrated comparator sampling architecture. The full scale input voltage is set by the voltage
at pin REF.
Figure 24. Equivalent Input Circuit
REF
C
HOLD
13pF
AIN
C
SWITCH
14pF
– +
Sample
Switch
C
HOLD
13pF
GND
– +
S&H and DAC
C
SWITCH
includes all parasitics
R
IN
+
–
Comparator
www.austriamicrosystems.com
Revision 1.03
11 - 21
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
