AS1526/AS1527
Data Sheet
- D e t a i l e d
Description
Figure 30. Supply Current vs. Sampling Rate
10000
Figure 31. Powerup Time vs. Time in Shutdown
800
700
Internal Reference
Supply Current (µA)
.
1000
Internal Reference
.
Power-Up delay (µs)
600
500
400
300
200
100
0
0.001
External Reference
3V
3V
100
10
1
0.1
0.1
10
1000
100000
0.01
0.1
1
10
Sam pling Rate (s ps )
Tim e in Shutdown (s )
Internal 2.5V Reference (AS1526)
The AS1526 internal 2.5V reference output is connected to pin REF and also drives the internal DAC
REF output can be used as a reference voltage source for other components and can source up to
400µA.
The internal reference is enabled by pulling pin SHDNN high. Letting SHDNN float disables the internal reference,
which allows the use of an external reference
Pin REF should be bypassed with a 4.7µF capacitor as shown in
Larger capacitors increase
wake-up time when the devices exit shutdown mode
External Reference
Both devices can operate with an external reference at pin REF. The external reference should be within the +1.0V to
V
DD
voltage range to achieve specified accuracy. The minimum input impedance is 18k
Ω
for DC currents.
Note:
To use an external reference with the AS1526, disable the internal reference by letting pin SHDNN float.
During conversion, the external reference should be capable of delivering up to 250µA of DC load current and have an
output impedance
≤
10
Ω
. The recommended minimum value for the bypass capacitor is 0.1µF. If the reference has
higher output impedance or is noisy, bypass it close to pin REF with a 4.7µF capacitor.
www.austriamicrosystems.com
Revision 1.03
15 - 21
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
