AS1526-BSOT Ver la hoja de datos (PDF) - austriamicrosystems AG
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AS1526-BSOT Datasheet PDF : 21 Pages
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AS1526/AS1527
Data Sheet - Detailed 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 (VDD ≤
3.6V).
Note: Pulling pin CSN low starts a conversion. The conversion result is available at pin DOUT in unipolar serial for-
mat (see Timing and Control on page 12).
Figure 23 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 VREF 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 VDD. The serial interface requires only three digital lines (at pins
SCLK, CSN, and DOUT) and provides a simple microprocessor interface.
Figure 23. Operational Diagram
+2.7 to +3.6V
+
4.7µF
0.1µF
Reference Input
Required for AS1527,
Optional for AS1526
1
8
VDD
SCLK
2
AIN
3
SHDNN
AS1526/
AS1527
7
CSN
6
DOUT
4
REF
AS1526 – 4.7µF
AS1527 – 0.1µF
5
GND
Analog Input
Figure 24 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
AIN
GND
CSWITCH includes all parasitics
CSWITCH
14pF
CHOLD
13pF
–+
Sample
Switch
CHOLD
RIN
13pF
–+
S&H and DAC
+
–
Comparator
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